Abstract

Introduction

Low back pain can affect up to 65% of the population per year and up to 84% during life span ¹1 Walker BF. The prevalence of low back pain: a systematic review of the literature from 1966 to 1998. J Spinal Disord 2000; 13:205-17., with a point prevalence of approximately 11.9% in the world population ²2 Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, et al. A systematic review of the global prevalence of low back pain. Arthritis Rheum 2012; 64:2028-37., which overloads all health services ³3 Hart LG, Deyo RA, Cherkin DC. Physician office visits for low back pain. Frequency, clinical evaluation, and treatment patterns from a U.S. national survey. Spine (Phila Pa 1976) 1995; 20:11-9.. However, these rates may be underestimated, since less than 60% of people with low back pain actually seek treatment ⁴4 Ferreira ML, Machado G, Latimer J, Maher C, Ferreira PH, Smeets RJ. Factors defining care-seeking in low back pain: a meta-analysis of population based surveys. Eur J Pain 2010; 14:747.e1-.e7.. Despite these numbers, a specific diagnosis presenting the causes of low back pain is not determined in 90-95% of the cases ⁵5 Krismer M, van Tulder M. Low back pain (non-specific). Best Pract Res Clin Rheumatol 2007; 21: 77-91., since low back pain has a multifactorial etiology ⁶6 O’Sullivan P. Diagnosis and classification of chronic low back pain disorders: maladaptive movement and motor control impairments as underlying mechanism. Man Ther 2005; 10:242-55.. Some authors ⁷7 Marras WS. Spine biomechanics, government regulation, and prevention of occupational low back pain. Spine J 2001; 1:163-5.^,88 Schneider S, Schmitt H, Zoller S, Schiltenwolf M. Workplace stress, lifestyle and social factors as correlates of back pain: a representative study of the German working population. Int Arch Occup Environ Health 2005; 78:253-69. relate the presence of low back pain to a set of causes, including social and demographic factors (such as age, gender, income, and schooling), health status, lifestyle or behavior factors (smoking, eating, and sedentary lifestyle), and occupation factors (such as heavy loadings and repetitive movements). However, a systematic review conducted by Vollin ⁹9 Volinn E. The epidemiology of low back pain in the rest of the world: a review of surveys in low- and middle-income countries. Spine (Phila Pa 1976) 1997; 22:1747-54. found that in the developed countries, where the physical demand of work tends to be less intense, prevalence of low back pain is twice as high as in low-income countries, where the physical demand of work is higher. Based on the findings of this study, sedentary lifestyle seems to have a greater impact on the occurrence of low back pain when compared to intense physical work.

Since low back pain is responsible for high rates of disability and work absenteeism. This condition imposes a high cost on the society, especially in developed countries ¹⁰10 Maetzel A, Li L. The economic burden of low back pain: a review of studies published between 1996 and 2001. Best Pract Res Clin Rheumatol 2002; 16:23-30.^,1111 Dagenais S, Caro J, Haldeman S. A systematic review of low back pain cost of illness studies in the United States and internationally. Spine J 2008; 8:8-20.^,1212 van Tulder MW, Koes BW, Bouter LM. A cost-of-illness study of back pain in The Netherlands. Pain 1995; 62:233-40.. Various studies ¹³13 Barker KL, Elliott CJ, Sackley CM, Fairbank JC. Treatment of chronic back pain by sensory discrimination training. A Phase I RCT of a novel device (FairMed) vs. TENS. BMC Musculoskelet Disord 2008; 9:97.^,1414 Hay EM, Dunn KM, Hill JC, Lewis M, Mason EE, Konstantinou K, et al. A randomised clinical trial of subgrouping and targeted treatment for low back pain compared with best current care. The STarT Back Trial Study Protocol. BMC Musculoskelet Disord 2008; 9:58.^,1515 Donzelli S, Di Domenica E, Cova AM, Galletti R, Giunta N. Two different techniques in the rehabilitation treatment of low back pain: a randomized controlled trial. Eura Medicophys 2006; 42:205-10.^,1616 Rasmussen-Barr E, Nilsson-Wikmar L, Arvidsson I. Stabilizing training compared with manual treatment in sub-acute and chronic low-back pain. Man Ther 2003; 8:233-41.^,1717 Kell RT, Asmundson GJ. A comparison of two forms of periodized exercise rehabilitation programs in the management of chronic nonspecific low-back pain. J Strength Cond Res 2009; 23:513-23.^,1818 Ewert T, Limm H, Wessels T, Rackwitz B, von Garnier K, Freumuth R, et al. The comparative effectiveness of a multimodal program versus exercise alone for the secondary prevention of chronic low back pain and disability. PM R 2009; 1:798-808.^,1919 Kuukkanen T, Malkia E, Kautiainen H, Pohjolainen T. Effectiveness of a home exercise programme in low back pain: a randomized five-year follow-up study. Physiother Res Int 2007; 12:213-24. in recent years have attempted to understand more about low back pain and how to manage it. However, precise estimates of low back pain prevalence are necessary to elucidate the developmental perspective of low back pain in different countries ²⁰20 Boyle MH. Guidelines for evaluating prevalence studies. Evid Based Ment Health 1998; 1:37-9.. Prevalence studies are widely used in epidemiology due their economic feasibility and easiness, with relatively short duration, providing indicators of the community’s health situation, based on evaluation of the individual health status in each member of the group and producing global health indicators for the target group ²¹21 Almeida Filho N, Rouquayrol MZ. Introdução à epidemiologia. Rio de Janeiro: Editora Guanabara Koogan; 2006..

According to the Brazilian National Household Sample Survey conducted by the Brazilian Institute of Geography and Statistics ²²22 Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostra de Domicílios. Um panorama da saúde no Brasil: acesso e utilização dos serviços, condições de saúde e fatores de risco e proteção à saúde, 2008. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2010., spinal pain (cervical, thoracic, lumbar, and pelvic pain) is the second most prevalent health condition in Brazil (13.5%) among the chronic conditions identified by a physician or other health professional. Spinal pain is overcomed only by hypertension (14%). However, this survey does not report specific prevalence rates for low back pain, which has different clinical manifestations and prognosis ²³23 Hayden JA, Dunn KM, van der Windt DA, Shaw WS. What is the prognosis of back pain? Best Pract Res Clin Rheumatol 2010; 24:167-79. when compared to cervical ²⁴24 Carroll LJ, Hogg-Johnson S, van der Velde G, Haldeman S, Holm LW, Carragee EJ, et al. Course and prognostic factors for neck pain in the general population: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders. Spine (Phila Pa 1976) 2008; 33(4 Suppl):S75-82., thoracic ²⁵25 Rex-Michael AL, Newman J, Seetharam Rao A. The assessment of thoracic pain. Orthop Trauma 2010; 24:63-73., and pelvic pain ²⁶26 Weijenborg PTM, Greeven A, Dekker FW, Peters AAW, ter Kuile MM. Clinical course of chronic pelvic pain in women. Pain 2007; 132 Suppl 1:S117-23.^,2727 Loving S, Nordling J, Jaszczak P, Thomsen T. Does evidence support physiotherapy management of adult female chronic pelvic pain? A systematic review. Scand J Pain 2012; 3:70-81.. The Brazilian population profile changed in recent years as the population is getting older, now representing 7.4% of Brazilians ²⁸28 Instituto Brasileiro de Geografia e Estatística. Censo demográfico. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2010., an increase in sedentary habits among adults ²⁹29 Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde. Rio de Janeiro: Ministério do Planejamento, Orçamento e Gestão; 2013., resulting in body composition alterations, increasing rates of overweight and obesity, which currently affect 58.4% and 52.5% of Brazilian women and men, respectively ³⁰30 Ng M, Fleming T, Robinson M, Thomson B, Graetz N, Margono C, et al. Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet 2014; 384:766-81.. Since these changes are risk factors for low back pain ²2 Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, et al. A systematic review of the global prevalence of low back pain. Arthritis Rheum 2012; 64:2028-37.^,3131 Shiri R, Karppinen J, Leino-Arjas P, Solovieva S, Viikari-Juntura E. The association between obesity and low back pain: a meta-analysis. Am J Epidemiol 2010; 171:135-54., knowledge of current prevalence of low back pain in Brazil is important to determine reference values for future comparisons, thereby verifying the impact of such changes on low back pain prevalence.

Data on prevalence of low back pain in Brazil have been obtained from studies in diverse segments of the Brazilian population, but to our knowledge there is no systematic review available on this topic. Therefore, information about the prevalence of low back pain in the Brazilian population is an important step to reveal the scope and extent of its effects, providing direction for preventive and intervention strategies ³²32 Hoy D, March L, Brooks P, Woolf A, Blyth F, Vos T, et al. Measuring the global burden of low back pain. Best Pract Res Clin Rheumatol 2010; 24:155-65.. Thus, the current study aimed to systematically review and to analyze the quality of the existing literature on LBP prevalence in Brazil.

Methods

Eligibility criteria

The study included all indexed articles in any language that reported data on the prevalence of low back pain in the overall Brazilian population or in specific categories (e.g., truck drivers, nurses, etc.), regardless of the definition of low back pain used by the authors, data collection instruments used, date of publication, age, or gender. Articles reporting prevalence of low back pain in pregnant women were excluded.

Search strategy

Electronic systematic searches on LILACS, PubMed, Embase, CINAHL, SPORTDiscus, and SciELO were conducted using specific search strategies (Table 1). The latest search was performed in May 2013. Articles were selected by two independent examiners (L.O.P.C. and P.R.C.N.) by reading the title or abstract. The potentially eligible articles were fully read. We also checked the reference lists from all eligible articles in order to retrieve new references for this review.

Risk of bias of individual studies

Considering that selected studies could present potential sources of bias and influence the results, the instrument developed by Hoy et al. ³³33 Hoy D, Brooks P, Woolf A, Blyth F, March L, Bain C, et al. Assessing risk of bias in prevalence studies: modification of an existing tool and evidence of interrater agreement. J Clin Epidemiol 2012; 65:934-9. (Table 2) was used to assess the risk of bias of the eligible studies. This instrument allows verifying the risk of bias for factors related to external and internal validity, allowing classification of the risk of bias as low, moderate, or high. This instrument was chosen mainly because it is easy to use, shows high inter-examiner agreement, and it was developed specifically to measure the risk of bias in prevalence studies for patients with low back pain ³³33 Hoy D, Brooks P, Woolf A, Blyth F, March L, Bain C, et al. Assessing risk of bias in prevalence studies: modification of an existing tool and evidence of interrater agreement. J Clin Epidemiol 2012; 65:934-9..

Risk of bias was analyzed by two independent reviewers (L.O.P.C. and P.R.C.N.) and based on the following: (1) representativeness of the study sample in relation to the Brazilian national population, allowing generalization of the results; (2) sampling system that represents the target population; (3) sample selection method; (4) probability of non-response bias; (5) how the target response was obtained; (6) definition of low back pain used for the sample selection; (7) reliability and validity of the study tools; (8) standardization of data collection; (9) appropriate target prevalence period; and (10) presence of error in calculating and/or reporting the numerator and denominator of the target parameter. The first four criteria relate to the study’s external validity, and the other items report the risk of bias for internal validity. At the end, the studies were classified as presenting low risk of bias when at least nine criteria were met, moderate risk of bias for studies that met seven or eight criteria, and high risk of bias when the studies met less than seven criteria. The reviewers discussed the cases in which there was no agreement and classification was determined by consensus. The levels of agreement between reviewers were not measured in this study. Table 2 presents the operationalization of each item.

Data extraction and statistical analysis

The target variables (first author, year of publication, type of study, data collection tool, sample size, population, age, gender, definition of low back pain, period of prevalence, and prevalence estimates) were extracted by one of the authors to an Excel spreadsheet (Microsoft Corp., USA) (Table 3). The target data were presented descriptively. Due to the high heterogeneity among the eligible studies, it was not possible to conduct a meta-analysis.

Results

The search strategy retrieved 263 articles, 63 of which were duplicates. After the screening process (titles, abstracts, and full text reading), 18 studies ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3535 Célia RCRS, Alexandre NMC. Distúrbios osteomusculares e qualidade de vida em trabalhadores envolvidos com transporte de pacientes. Rev Bras Enferm 2003; 56:494-8.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,3737 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,3838 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,4040 Andrusaitis SF, Oliveira RP, Barros Filho TEP. Study of the prevalence and risk factors for low back pain in truck drivers in the state of São Paulo, Brazil. Clinics 2006; 61:503-10.^,4141 Kreling MC, da Cruz DA, Pimenta CA. Prevalência de dor crônica em adultos. Rev Bras Enferm 2006; 59:509-13.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4545 de Vitta A, Martinez MG, Piza NT, Simeão SFAP, Ferreira NP. Prevalência e fatores associados à dor lombar em escolares. Cad Saúde Pública 2011; 27:1520-8.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5.^,4747 Fernandes RCP, Carvalho FM, Assunção AA. Prevalence of musculoskeletal disorders among plastics industry workers. Cad Saúde Pública 2011; 27:78-86.^,4848 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,4949 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155. (with a population of 19,387 individuals and samples varying from 56 to 3,269 participants ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.) met the inclusion criteria. Figure 1 shows flow diagram of this review.

The eligible studies showed the recent interest in prevalence of low back pain in the Brazilian population, with the first article published in 1998 ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27. and the remaining ones were published over the last 10 years. Most of the studies included males and females, ranging from children ³⁹39 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74. to the elderly ⁵⁰50 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34., with populations residing in urban and rural areas ⁴⁴44 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6., but none showed separate prevalence values according to gender. Three studies ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6. reported on the prevalence of low back pain exclusively in women, two of which presenting the rates observed in female urban workers ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13. and one in female farm laborers ⁴⁴44 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6., but the different prevalence periods prevented any comparison. The principal research design was cross-sectional. Data collection used original questionnaires in 50% of the studies ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3737 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,4040 Andrusaitis SF, Oliveira RP, Barros Filho TEP. Study of the prevalence and risk factors for low back pain in truck drivers in the state of São Paulo, Brazil. Clinics 2006; 61:503-10.^,4141 Kreling MC, da Cruz DA, Pimenta CA. Prevalência de dor crônica em adultos. Rev Bras Enferm 2006; 59:509-13.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5.^,4949 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34., while the Nordic questionnaire ⁵²52 de Barros EN, Alexandre NM. Cross-cultural adaptation of the Nordic musculoskeletal questionnaire. Int Nurs Rev 2003; 50:101-8. was used in the remaining studies ³⁵35 Célia RCRS, Alexandre NMC. Distúrbios osteomusculares e qualidade de vida em trabalhadores envolvidos com transporte de pacientes. Rev Bras Enferm 2003; 56:494-8.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,3838 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22.^,4545 de Vitta A, Martinez MG, Piza NT, Simeão SFAP, Ferreira NP. Prevalência e fatores associados à dor lombar em escolares. Cad Saúde Pública 2011; 27:1520-8.^,4747 Fernandes RCP, Carvalho FM, Assunção AA. Prevalence of musculoskeletal disorders among plastics industry workers. Cad Saúde Pública 2011; 27:78-86.^,4848 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155.. In most of the studies, prevalence of low back pain was verified in specific groups of workers or in students. Chronic low back pain was more prevalent in the population in Salvador, in Northeast Brazil ⁴²42 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102. (14.7%), than in Pelotas in the South ³⁸38 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155. (4.2% and 9.6%). Three studies only presented clear definitions of low back pain ⁴⁰40 Andrusaitis SF, Oliveira RP, Barros Filho TEP. Study of the prevalence and risk factors for low back pain in truck drivers in the state of São Paulo, Brazil. Clinics 2006; 61:503-10.^,4545 de Vitta A, Martinez MG, Piza NT, Simeão SFAP, Ferreira NP. Prevalência e fatores associados à dor lombar em escolares. Cad Saúde Pública 2011; 27:1520-8.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5., nevertheless using different concepts. No study in this review reported the minimum duration of pain in order to be considerate as an episode of low back pain. The most common prevalence estimates were one year prevalence, seven days prevalence. The high heterogeneity of eligible studies also prevented a summary prevalence rate over time in most of the periods analyzed, and it was only possible to verify the one-year prevalence of low back pain, reaching more than 50% of adults ³⁵35 Célia RCRS, Alexandre NMC. Distúrbios osteomusculares e qualidade de vida em trabalhadores envolvidos com transporte de pacientes. Rev Bras Enferm 2003; 56:494-8.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22. and 13.1% to 19.5% of adolescents ³⁹39 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,4545 de Vitta A, Martinez MG, Piza NT, Simeão SFAP, Ferreira NP. Prevalência e fatores associados à dor lombar em escolares. Cad Saúde Pública 2011; 27:1520-8., whereas chronic low back pain affected between 4.2% and 14.7% of the overall population ³⁸38 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102..

The risk of bias in the eligible studies ranged from 4 ³⁷37 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6. to 8 ³⁸38 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155. of a 10 possible points. Classification of the overall risk of bias showed that 11 studies ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3535 Célia RCRS, Alexandre NMC. Distúrbios osteomusculares e qualidade de vida em trabalhadores envolvidos com transporte de pacientes. Rev Bras Enferm 2003; 56:494-8.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,3737 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,4040 Andrusaitis SF, Oliveira RP, Barros Filho TEP. Study of the prevalence and risk factors for low back pain in truck drivers in the state of São Paulo, Brazil. Clinics 2006; 61:503-10.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4747 Fernandes RCP, Carvalho FM, Assunção AA. Prevalence of musculoskeletal disorders among plastics industry workers. Cad Saúde Pública 2011; 27:78-86.^,4949 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34. presented high risk of bias, while seven studies ³⁸38 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,4141 Kreling MC, da Cruz DA, Pimenta CA. Prevalência de dor crônica em adultos. Rev Bras Enferm 2006; 59:509-13.^,4545 de Vitta A, Martinez MG, Piza NT, Simeão SFAP, Ferreira NP. Prevalência e fatores associados à dor lombar em escolares. Cad Saúde Pública 2011; 27:1520-8.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5.^,4848 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155. had moderate risk of bias. Greater risk of bias was found in the criteria related to external validity: representativeness of Brazilian national population (18 studies), sampling system (15 studies), sample selection method (12 studies), and non-response bias (5 studies). The items referring to internal validity: definition of low back pain, and realibility and validity of the study tools were not completed in 15 ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3535 Célia RCRS, Alexandre NMC. Distúrbios osteomusculares e qualidade de vida em trabalhadores envolvidos com transporte de pacientes. Rev Bras Enferm 2003; 56:494-8.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,3737 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,3838 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,4141 Kreling MC, da Cruz DA, Pimenta CA. Prevalência de dor crônica em adultos. Rev Bras Enferm 2006; 59:509-13.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4747 Fernandes RCP, Carvalho FM, Assunção AA. Prevalence of musculoskeletal disorders among plastics industry workers. Cad Saúde Pública 2011; 27:78-86.^,4848 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,4949 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155. and 8 ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3737 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,4141 Kreling MC, da Cruz DA, Pimenta CA. Prevalência de dor crônica em adultos. Rev Bras Enferm 2006; 59:509-13.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5.^,4949 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34. of the studies, respectively. Table 4 shows the criteria for evaluating risk of bias in each study.

Discussion

This review systematically evaluated and analyzed the methodological quality of the existing literature reporting data on the prevalence of low back pain in the Brazilian population. To our knowledge, this is the first systematic review on the prevalence of low back pain in Brazil. Our review showed the recent interest in the epidemiology of low back pain in Brazil, with most of the studies published over the last ten years.

The recent interest in researching the prevalence of low back pain in the Brazilian population may reflect the rising financial costs for health services and the social security system in recent years ⁵³53 Meziat Filho N, Silva GA. Invalidez por dor nas costas entre segurados da Previdência Social do Brasil. Rev Saúde Pública 2011; 45:494-502.. Likewise, studies on the prevalence of low back pain in Africa ⁵⁴54 Louw QA, Morris LD, Grimmer-Somers K. The prevalence of low back pain in Africa: a systematic review. BMC Musculoskelet Disord 2007; 8:105. and the occurrence of global low back pain ¹1 Walker BF. The prevalence of low back pain: a systematic review of the literature from 1966 to 1998. J Spinal Disord 2000; 13:205-17. also reflect the recent interest on this topic.

The most interesting result of the current review is the higher prevalence of chronic low back pain in the city of Salvador ⁴²42 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102. (14.7%) when compared to the city of Pelotas, as reported in two studies ³⁸38 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155., estimated at 4.2% and 9.6%. The study population in Salvador presented some different characteristics, for example more non-white individuals (70.2%), lower social class (55.2%), low schooling (42.6%), obesity (50.4%), and sedentary lifestyle (71.5%) when compared to the Pelotas sample, and these differences may have contributed to the higher prevalence of low back pain observed in Salvador ⁴⁹49 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5555 Hestbaek L, Larsen K, Weidick F, Leboeuf-Yde C. Low back pain in military recruits in relation to social background and previous low back pain. A cross-sectional and prospective observational survey. BMC Musculoskelet Disord 2005; 6:25.^,5656 Bjorck-van Dijken C, Fjellman-Wiklund A, Hildingsson C. Low back pain, lifestyle factors and physical activity: a population based-study. J Rehabil Med 2008; 40:864-9.^,5757 Valat JP, Goupille P, Vedere V. Low back pain: risk factors for chronicity. Rev Rhum Engl Ed 1997; 64:189-94.^,5858 Shiri R, Karppinen J, Leino-Arjas P, Solovieva S, Viikari-Juntura E. The association between obesity and low back pain: a meta-analysis. Am J Epidemiol 2010; 171:135-54.^,5959 Sitthipornvorakul E, Janwantanakul P, Purepong N, Pensri P, van der Beek AJ. The association between physical activity and neck and low back pain: a systematic review. Eur Spine J 2011; 20: 677-89.^,6060 Taanila HP, Suni JH, Pihlajamaki HK, Mattila VM, Ohrankammen O, Vuorinen P, et al. Predictors of low back pain in physically active conscripts with special emphasis on muscular fitness. Spine J 2012; 12:737-48.. However, we believe that the main determinant of the difference in prevalence rates was the studies’ lack of methodological rigor. The two studies in Pelotas showed a moderate overall risk of bias, while the study in Salvador showed a high overall risk of bias, potentially influencing the prevalence rates. Despite the high prevalence of chronic low back pain in adults in Salvador when compared to Pelotas, the rates found in Salvador were lower than the mean value (19.4%) in the world population ²2 Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, et al. A systematic review of the global prevalence of low back pain. Arthritis Rheum 2012; 64:2028-37.. Still, we cannot claim that the prevalence of chronic low back pain in Brazil is lower, since the rates are based only on regional data of studies with poor methodological quality. Our results revealed the heterogeneity of methods, data collection, types of study population, and results, thus preventing any significant pooling of data, the same problem reported in other reviews ¹1 Walker BF. The prevalence of low back pain: a systematic review of the literature from 1966 to 1998. J Spinal Disord 2000; 13:205-17.^,22 Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, et al. A systematic review of the global prevalence of low back pain. Arthritis Rheum 2012; 64:2028-37.^,5454 Louw QA, Morris LD, Grimmer-Somers K. The prevalence of low back pain in Africa: a systematic review. BMC Musculoskelet Disord 2007; 8:105.^,6161 Dionne CE, Dunn KM, Croft PR. Does back pain prevalence really decrease with increasing age? A systematic review. Age Ageing 2006; 35:229-34.. In addition, most of the studies reported prevalence rates for workers and students, as observed by Louw et al. ⁵⁴54 Louw QA, Morris LD, Grimmer-Somers K. The prevalence of low back pain in Africa: a systematic review. BMC Musculoskelet Disord 2007; 8:105.. The preference for these population groups may have been due to sample feasibility and the presence of characteristics defined as risk factors for low back pain, such as greater stress ⁶²62 Pincus T, Burton AK, Vogel S, Field AP. A systematic review of psychological factors as predictors of chronicity/disability in prospective cohorts of low back pain. Spine (Phila Pa 1976) 2002; 27:E109-20. and sustained postures ⁶³63 Thorbjornsson CB, Alfredsson L, Fredriksson K, Michelsen H, Punnett L, Vingard E, et al. Physical and psychosocial factors related to low back pain during a 24-year period. A nested case-control analysis. Spine (Phila Pa 1976) 2000; 25:369-74.^,6464 Bakker EW, Verhagen AP, Lucas C, Koning HJ, de Haan RJ, Koes BW. Daily spinal mechanical loading as a risk factor for acute non-specific low back pain: a case-control study using the 24-Hour Schedule. Eur Spine J 2007; 16:107-13.^,6565 Coenen P, Kingma I, Boot CR, Twisk JW, Bongers PM, van Dieen JH. Cumulative low back load at work as a risk factor of low back pain: a prospective cohort study. J Occup Rehabil 2013; 23:11-8.. The study of low back pain prevalence in students allows knowing the problem’s size in this population group, and also establishing possible etiological factors, since according to their school grade, accelerated growth and strain in specific muscles can occur, in addition to daily habits like smoking, all known risk factors for low back pain ⁶⁶66 Feldman DE, Shrier I, Rossignol M, Abenhaim L. Risk factors for the development of low back pain in adolescence. Am J Epidemiol 2001; 154:30-6.^,6767 Shiri R, Karppinen J, Leino-Arjas P, Solovieva S, Viikari-Juntura E. The association between smoking and low back pain: a meta-analysis. Am J Med 2010; 123:87.e7-35.. Knowledge of modifiable risk factors is important to establish preventive strategies, since low back pain in adulthood is more common in individuals that already presented the symptoms during adolescence ⁶⁸68 Harreby M, Kjer J, Hesselsoe G, Neergaard K. Epidemiological aspects and risk factors for low back pain in 38-year-old men and women: a 25-year prospective cohort study of 640 school children. Eur Spine J 1996; 5:312-8.^,6969 Hestbaek L, Leboeuf-Yde C, Kyvik KO, Manniche C. The course of low back pain from adolescence to adulthood: eight-year follow-up of 9600 twins. Spine (Phila Pa 1976) 2006; 31:468-72..

This review’s main finding is that the studies on prevalence of low back pain in Brazilian population show significant limitations in the methodological design of aspects related to external and internal validity. Among the criteria for external validity, none of the studies presented a sample that represented Brazilian national population, while the samples consisted mainly of the population in municipalities with research centers and specific population groups. Studies with samples that represent the national population are difficult, since they require a larger team and high financial cost. The solution to this problem may be multicenter studies involving research groups from different regions of the country. Only two studies ⁴⁸48 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34. described the sample calculation in their methods. The studies that met eligible criteria in this review generally presented an insufficient sample. According to the methodological review by Loney & Stratford ⁷⁰70 Loney PL, Stratford PW. The prevalence of low back pain in adults: a methodological review of the literature. Phys Ther 1999; 79:384-96., considering the proportion of individuals that suffer from low back pain, the adequate sample size for prevalence studies on low back pain should be 1,067 participants. The sampling system was considered inadequate in eight studies ³⁵35 Célia RCRS, Alexandre NMC. Distúrbios osteomusculares e qualidade de vida em trabalhadores envolvidos com transporte de pacientes. Rev Bras Enferm 2003; 56:494-8.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,4040 Andrusaitis SF, Oliveira RP, Barros Filho TEP. Study of the prevalence and risk factors for low back pain in truck drivers in the state of São Paulo, Brazil. Clinics 2006; 61:503-10.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4545 de Vitta A, Martinez MG, Piza NT, Simeão SFAP, Ferreira NP. Prevalência e fatores associados à dor lombar em escolares. Cad Saúde Pública 2011; 27:1520-8.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5.^,4747 Fernandes RCP, Carvalho FM, Assunção AA. Prevalence of musculoskeletal disorders among plastics industry workers. Cad Saúde Pública 2011; 27:78-86., which involved only a specific subgroup of the population not described in the title (e.g., students, nurses, truck drivers, etc.). Only six studies used a proper sample selection method like a random selection ³⁸38 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,4141 Kreling MC, da Cruz DA, Pimenta CA. Prevalência de dor crônica em adultos. Rev Bras Enferm 2006; 59:509-13.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4848 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155.. In the others, convenience sample was the principal form of participant selection. Many researchers prefer this sampling technique due to its ease, speed, and low cost ⁷¹71 Guimarães PRB. Métodos quantitativos estatísticos. Curitiba: IESDE Brasil S.A.; 2008.. However, this sampling process may be biased, generating systematic error and failing to reflect the true prevalence of low back pain in the study population ⁷¹71 Guimarães PRB. Métodos quantitativos estatísticos. Curitiba: IESDE Brasil S.A.; 2008.. Ten studies showed a risk of non-response bias ³⁷37 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,4040 Andrusaitis SF, Oliveira RP, Barros Filho TEP. Study of the prevalence and risk factors for low back pain in truck drivers in the state of São Paulo, Brazil. Clinics 2006; 61:503-10.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5.^,4747 Fernandes RCP, Carvalho FM, Assunção AA. Prevalence of musculoskeletal disorders among plastics industry workers. Cad Saúde Pública 2011; 27:78-86.^,4848 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,4949 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34. by failing to report the occurrence of losses or refusals, which can generate confounding factors and prevent generalization of the results. Again, the lack of transparency on this item can lead to biased prevalence estimates.

The items referring to internal validity, definition of low back pain, and realibility and validity of study tools were not completed in 15 ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3535 Célia RCRS, Alexandre NMC. Distúrbios osteomusculares e qualidade de vida em trabalhadores envolvidos com transporte de pacientes. Rev Bras Enferm 2003; 56:494-8.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,3737 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,3838 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,4141 Kreling MC, da Cruz DA, Pimenta CA. Prevalência de dor crônica em adultos. Rev Bras Enferm 2006; 59:509-13.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4747 Fernandes RCP, Carvalho FM, Assunção AA. Prevalence of musculoskeletal disorders among plastics industry workers. Cad Saúde Pública 2011; 27:78-86.^,4848 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,4949 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155. and 8 studies ³⁴34 Araujo IEM, Alexandre NMC. Ocorrência de cervicodorsolombalgias em funcionários de enfermagem em centro cirúrgico. Rev Bras Saúde Ocup 1998; 25:119-27.^,3737 Peres CPA. The postural disturbances in physical therapists: an occupational biomechanic approach. Fisioter Mov 2004; 17:19-25.^,4141 Kreling MC, da Cruz DA, Pimenta CA. Prevalência de dor crônica em adultos. Rev Bras Enferm 2006; 59:509-13.^,4242 Almeida ICGB, Sá KN, Silva M, Baptista A, Matos MA, Lessa I. Prevalência de dor lombar crônica na população da cidade de Salvador. Rev Bras Ortop 2008; 43:96-102.^,4444 Motta AF, Cardoso FL, Sacomori C, Sperandio FF, Santos GM. Dor lombar auto-referida em mulheres trabalhadoras rurais de sete comunidades de Concórdia-SC. Ter Man 2010; 8:10-6.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5.^,4949 Onofrio AC, Da Silva MC, Domingues MR, Rombaldi AJ. Acute low back pain in high school adolescents in Southern Brazil: prevalence and associated factors. Eur Spine J 2012; 21:1234-40.^,5050 Dellaroza MS, Pimenta CA, Duarte YA, Lebrão ML. Dor crônica em idosos residentes em São Paulo, Brasil: prevalência, características e associação com capacidade funcional e mobilidade (Estudo SABE). Cad Saúde Pública 2013; 29:325-34., respectively. Only three studies ⁴⁰40 Andrusaitis SF, Oliveira RP, Barros Filho TEP. Study of the prevalence and risk factors for low back pain in truck drivers in the state of São Paulo, Brazil. Clinics 2006; 61:503-10.^,4545 de Vitta A, Martinez MG, Piza NT, Simeão SFAP, Ferreira NP. Prevalência e fatores associados à dor lombar em escolares. Cad Saúde Pública 2011; 27:1520-8.^,4646 Falavigna A, Teles AR, Mazzocchin T, De Braga GL, Kleber FD, Barreto F, et al. Increased prevalence of low back pain among physiotherapy students compared to medical students. Eur Spine J 2011; 20:500-5. cited what they defined as low back pain, with distinct definitions: “pain between the lower part of the ribs and the gluteal fold, not related to injuries or falls”, “pain or discomfort in the last 12 months not related to trauma or menstrual colic”, and “pain in the area between the ribs and the hips”. According to a consensus on low back pain in prevalence studies ⁷²72 Dionne CE, Dunn KM, Croft PR, Nachemson AL, Buchbinder R, Walker BF, et al. A consensus approach toward the standardization of back pain definitions for use in prevalence studies. Spine (Phila Pa 1976) 2008; 33:95-103., an ideal definition of low back pain should include the site of the pain, symptoms, duration, frequency, and severity.

Data were also collected in a non standardized way, so that only half of the 18 eligible studies ³⁵35 Célia RCRS, Alexandre NMC. Distúrbios osteomusculares e qualidade de vida em trabalhadores envolvidos com transporte de pacientes. Rev Bras Enferm 2003; 56:494-8.^,3636 Gurgueira GP, Alexandre NMC, Corrêa Filho HR. Prevalência de sintomas músculo-esqueléticos em trabalhadoras de enfermagem. Rev Latinoam Enferm 2003; 11:608-13.^,3838 Silva MC, Fassa AG, Valle NC. Chronic low back pain in a Southern Brazilian adult population: prevalence and associated factors. Cad Saúde Pública 2004; 20:377-85.^,3939 Fassa AG, Facchini LA, Dall’Agnol MM, Christiani DC. Child labor and musculoskeletal disorders: the Pelotas (Brazil) epidemiological survey. Public Health Rep 2005; 120:665-74.^,4343 Matos MG, Hennington EA, Hoefel AL, Dias-da-Costa JS. Lower back pain in health insurance policyholders: prevalence and associated factors. Cad Saúde Pública 2008; 24:2115-22.^,4545 de Vitta A, Martinez MG, Piza NT, Simeão SFAP, Ferreira NP. Prevalência e fatores associados à dor lombar em escolares. Cad Saúde Pública 2011; 27:1520-8.^,4747 Fernandes RCP, Carvalho FM, Assunção AA. Prevalence of musculoskeletal disorders among plastics industry workers. Cad Saúde Pública 2011; 27:78-86.^,4848 Ferreira GD, Silva MC, Rombaldi AJ, Wrege ED, Siqueira FV, Hallal PC. Prevalence and associated factors of back pain in adults from Southern Brazil: a population-based study. Rev Bras Fisioter 2011; 15:31-6.^,5151 Meucci RD, Fassa AG, Paniz VMV, Silva MC, Wegman DH. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil. BMC Musculoskelet Disord 2013; 14:155. used the Standardized Nordic Questionnaire as proposed previously by Lebouef-Yde & Lauritsen ⁷³73 Leboeuf-Yde C, Lauritsen JM. The prevalence of low back pain in the literature. A structured review of 26 Nordic studies from 1954 to 1993. Spine (Phila Pa 1976) 1995; 20:2112-8.. Similar findings came from the review published in 2000 by Walker ¹1 Walker BF. The prevalence of low back pain: a systematic review of the literature from 1966 to 1998. J Spinal Disord 2000; 13:205-17.. As demonstrated in the literature, the way the questionnaire is applied and the selected tool itself influence the results of prevalence studies ⁷⁴74 Kelley K, Clark B, Brown V, Sitzia J. Good practice in the conduct and reporting of survey research. Int J Qual Health Care 2003; 15:261-6.. A systematic review by Hoy et al. ²2 Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, et al. A systematic review of the global prevalence of low back pain. Arthritis Rheum 2012; 64:2028-37. found that a high risk of bias for case definition and validity and reliability of the study tools was associated with results reporting higher prevalence.

Our study has some limitations. We attempted to minimize these limitations by evaluating the methodological criteria of the eligible studies, but unlike other reviews ¹1 Walker BF. The prevalence of low back pain: a systematic review of the literature from 1966 to 1998. J Spinal Disord 2000; 13:205-17.^,22 Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, et al. A systematic review of the global prevalence of low back pain. Arthritis Rheum 2012; 64:2028-37.^,5454 Louw QA, Morris LD, Grimmer-Somers K. The prevalence of low back pain in Africa: a systematic review. BMC Musculoskelet Disord 2007; 8:105. we did not establish a cut-off point based on this methodological evaluation in order to include the studies in this review. This decision was due to the low number of studies that would have met the inclusion criteria considering this parameter, as well the fact that this was the first systematic review as far as we know on the prevalence of low back pain in Brazil, which helps explain these shortcomings and points to possible ways to overcome them.

Our review showed that the different studies that attempted to measure the prevalence of low back pain found a high one-year prevalence rate (> 50%) in adults, from 13.1% to 19.5% in adolescents, and prevalence rates of 4.2% to 14.7% for chronic low back pain in the general population. Due to the high risk of bias of the eligible studies, these rates may not reflect the real impact of low back pain in Brazil. The lack of precise epidemiological data hinders the development of preventive strategies and adequate management, which can result in worse prognosis ⁷⁵75 Costa LCM, Maher CG, Hancock MJ, McAuley JH, Herbert RD, Costa LOP. The prognosis of acute and persistent low-back pain: a meta-analysis. CMAJ 2012; 184:E613-24..

This study helped to reveal the main shortcomings of the current studies on the prevalence of low back pain in the Brazilian population. These findings can guide actions to produce robust evidence on this topic in the future. We strongly recommend future robust studies with low risk of bias.

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