Abstract

This cross-sectional study evaluated the association of biopsychosocial factors with disability in older adults with a new episode of acute low back pain. Older patients with a new episode of acute low back pain were included and those with cognitive alterations and severe motor impairment were excluded. Disability was assessed using the Roland Morris Disability Questionnaire. The biopsychosocial factors (clinical, functional, health status, psychological and social variables) were evaluated by a structured multidimensional questionnaire and physical examination. A multivariate linear regression was used to analyze data with a statistical significance of 0.05. A total of 386 older individuals with a mean age of 71.6 (± 4.2) years and disability of 13.7 (± 5.7) points were enrolled. Our regression analyses identified that worse physical and mental health (assessed through SF-36), low falls self-efficacy, trouble sleeping due to pain, worse kinesiophobia levels, higher body mass indexes, lumbar morning stiffness, increased pain intensity, female gender and worse functional mobility were significantly associated with baseline disability (p < 0.05). Low back pain-related disability is significantly associated with worse biopsychosocial health conditions in older adults.

Low back pain; Disability; Older adults; Aging

Introduction

Low back pain (LBP) is the leading cause of physical disability¹1. Hoy D, March L, Brooks P, Blyth F, Woolf A, Bain C, Williams G, Smith E, Vos T, Barendregt J, Murray C, Burstein R, Buchbinder R. The global burden of low back pain: estimates from the Global Burden of Disease 2010 study. Ann Rheum Dis 2014; 73(6):968-974. among adults of all ages. According to data from the World Health Organization (WHO), musculoskeletal morbidities are the conditions with the highest incapacitating burden²2. Klijs B, Nusselder WJ, Looman CW, Mackenbach JP. Contribution of chronic disease to the burden of disability. PLoS One [periódico na Internet] 2011 [acessado 2015 Jan 16]; 6(9):[cerca de 8p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC 3178640/pdf/pone.0025325.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... ,³3. Smith E, Hoy DG, Cross M, Vos T, Naghavi M, Buchbinder R, Woolf AD, March L. The global burden of other musculoskeletal disorders: estimates from the Global Burden of Disease 2010 study. Ann Rheum Dis 2014; 73(8):1462-1469.. Of the 209 health conditions, LBP is the morbidity that contributes most to overall disability and ranks sixth in the global burden of disease measured by Disability-Adjusted Life Years (DALYs)¹1. Hoy D, March L, Brooks P, Blyth F, Woolf A, Bain C, Williams G, Smith E, Vos T, Barendregt J, Murray C, Burstein R, Buchbinder R. The global burden of low back pain: estimates from the Global Burden of Disease 2010 study. Ann Rheum Dis 2014; 73(6):968-974.. Patients with acute LBP have a higher severity of pain and disability symptoms when compared to people with chronic LBP⁴4. Costa LCM, Maher CG, Hancock MJ, McAuley JH, Herbert RD, Costa LO. The prognosis of acute and persistent low-back pain: a meta-analysis. CMAJ 2012; 184(11):E613-E624.. In this rationale, it is important to differentiate patients with acute and chronic complaints in research and studies on LBP⁵5. Balague F, Mannion AF, Pellise F, Cedraschi C. Non-specific low back pain. Lancet 2012; 379(9814):482-491..

The prevalence of LBP of greater severity increases with age⁶6. Dionne CE, Dunn KM, Croft PR. Does back pain prevalence really decrease with increasing age? A systematic review. Age Ageing 2006; 35(3):229-234.,⁷7. Docking RE, Fleming J, Brayne C, Zhao J, Macfarlane GJ, Jones GT. Epidemiology of back pain in older adults: prevalence and risk factors for back pain onset. Rheumatology (Oxford) 2011; 50(9):1645-1653., contributing significantly to the disabilities and deteriorating health conditions already present in the elderly population⁸8. Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, Woolf A, Vos T, Buchbinder R. A systematic review of the global prevalence of low back pain. Arthritis Rheum 2012; 64(6):2028-2037.. Seniors with disabilities are unable to keep up their daily activities and tend to move away from the interaction, adversely affecting their health status⁹9. Rudy TE, Weiner DK, Lieber SJ, Slaboda J, Boston JR. The impact of chronic low back pain on older adults: a comparative study of patients and controls. Pain 2007; 131(3):293-301.. LBP compromises functionality, autonomy and independence of older adults¹⁰10. Weiner DK, Haggerty CL, Kritchevsky SB, Harris T, Simonsick EM, Nevitt M, Newman A. How does low back pain impact physical function in independent, well-functioning older adults? Evidence from the Health ABC Cohort and implications for the future. Pain Med 2003; 4(4):311-320. and is one of the most common reasons for seeking primary health care¹¹11. Cayea D, Perera S, Weiner D. Cronic low back pain in older adultes: what physicians kow, what they think they kwow, and what they should be taught. J Am Geriatr Soc 2006; 54(11):1772-1777.. Cayea et al.¹¹11. Cayea D, Perera S, Weiner D. Cronic low back pain in older adultes: what physicians kow, what they think they kwow, and what they should be taught. J Am Geriatr Soc 2006; 54(11):1772-1777. reported that 36% of the community aged 65 years and over were affected by one LBP episode per year, and of these, 21% sought health care. Moreover, the social and economic costs related to LBP disabilities are significant, further burdening the health and social security system¹²12. Salvetti MG, Pimenta CA, Braga PE, Correa CF. Disability related to chronic low back pain: prevalence and associated factors. Rev Esc Enferm USP 2012; 46(n. esp):16-23..

The definition of disability proposed by the WHO International Classification of Functioning, Disability and Health (ICF) postulates that disabilities related to health conditions are influenced by multiple factors. In ICF, disabilities result from the interaction between dysfunctions in body structure and function, limited activity and restricted social participation, and are also influenced by personal and environmental aspects¹³13. Escorpizo R. Defining the principles of musculoskeletal disability and rehabilitation. Best Pract Res Clin Rheumatol 2014; 28(3):367-375.. Waddell et al. analyzed LBP under the biopsychosocial model¹⁴14. Waddell G. Biopsychosocial analysis of low back pain. Baillieres Clin Rheumatol 1992; 6(3):523-557., and since then, this approach has been disseminated and improved¹⁵15. Weiner BK. Spine update: the biopsychosocial model and spine care. Spine (Phila Pa 1976) 2008; 33(2):219-223.,¹⁶16. Gatchel RJ, Peng YB, Peters ML, Fuchs PN, Turk DC. The biopsychosocial approach to chronic pain: scientific advances and future directions. Psychol Bull 2007; 133(4):581-624.. According to the biopsychosocial model, disability in individuals with LBP can be influenced by biological, psychological and socio-environmental aspects, and should be analyzed in this broad and integrative context¹⁴14. Waddell G. Biopsychosocial analysis of low back pain. Baillieres Clin Rheumatol 1992; 6(3):523-557..

The scientific literature highlights the importance of the biopsychosocial model in the approach of LBP in the general population¹⁷17. Bath B, Trask C, McCrosky J, Lawson J. A biopsychosocial profile of adult Canadians with and without chronic back disorders: a population-based analysis of the 2009-2010 Canadian Community Health Surveys. Biomed Res Int [periódico na Internet] 2014 [acessado 2016 Jan 12]; 2014:[cerca de 11p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4058275/pdf/BMRI2014-919621.pdf
https://www.ncbi.nlm.nih.gov/pmc/article...

18. Hulla R, Moomey M, Garner T, Ray C, Gatchel RJ. Biopsychosocial Characteristics, Using a New Functional Measure of Balance, of an Elderly Population with CLBP. Healthcare (Basel) [periódico na Internet] 2016 [acessado 2017 Mar 9]; 4(3):[cerca de 9p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5041060/pdf/healthcare-04-00059.pdf
https://www.ncbi.nlm.nih.gov/pmc/article...

19. Pensri P, Janwantanakul P, Worakul P, Sinsongsook T. Biopsychosocial factors and perceived disability in saleswomen with concurrent low back pain. Saf Health Work 2010; 1(2):149-157.-²⁰20. Koenig AL, Kupper AE, Skidmore JR, Murphy KM. Biopsychosocial functioning and pain self-efficacy in chronic low back pain patients. J Rehabil Res Dev 2014; 51(8):1277-1286.. However, on the association of biopsychosocial factors with disability in LBP patients are still limited. The few available data point to the influence of physical, psychological and socio-environmental factors on self-reported disability in adults with acute LBP¹⁹19. Pensri P, Janwantanakul P, Worakul P, Sinsongsook T. Biopsychosocial factors and perceived disability in saleswomen with concurrent low back pain. Saf Health Work 2010; 1(2):149-157.. In older adults, the only study available on the biopsychosocial and LBP model showed an association of negative biopsychosocial aspects with worse functional results and recommended the use of the biopsychosocial approach in future research on LBP in older adults¹⁸18. Hulla R, Moomey M, Garner T, Ray C, Gatchel RJ. Biopsychosocial Characteristics, Using a New Functional Measure of Balance, of an Elderly Population with CLBP. Healthcare (Basel) [periódico na Internet] 2016 [acessado 2017 Mar 9]; 4(3):[cerca de 9p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5041060/pdf/healthcare-04-00059.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... .

However, there are still few studies on LBP and disability in the older population, mainly from a biopsychosocial viewpoint. Thus, it is necessary to investigate the association of biopsychosocial factors with LBP and its consequences among older adults. Thus, this study aimed to identify whether selected biopsychosocial factors were associated with disability in seniors affected by a new episode of acute LBP.

Methods

Study design

This study is part of the international consortium of epidemiological studies Back Complaints in the Elders – BACE, which includes researchers from Australia, Brazil and the Netherlands. The consortium aims to study the clinical, functional, sociodemographic profile, as well as to investigate the course of LBP in seniors of health care services in the countries involved, whose protocol details have been previously published²¹21. Scheele J, Luijsterburg PA, Ferreira ML, Maher CG, Pereira L, Peul WC, Van Tulder MW, Bohnen AM, Berger MY, Bierma-Zeinstra SM, Koes BW. Back complaints in the elders (BACE); design of cohort studies in primary care: an international consortium. BMC Musculoskelet Disord [periódico na Internet] 2011[acessado 2011 Out 23]; 12:[cerca de 9p. ]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182961/pdf/1471-2474-12-193.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... . The BACE-Brasil project (BACE-B) is a prospective cohort study with data collected between October 2011 and September 2015. The recruitment of BACE-B allowed the construction of an extensive database, facilitating both cross-sectional and longitudinal (prospective) analyses. This is an observational cross-sectional study of baseline assessment data from the BACE-B cohort.

The BACE-B study was approved by the Research Ethics Committee of the Federal University of Minas Gerais, and recruited a consecutive sample of older adults with acute LBP complaints and residents of the community of the metropolitan region of Belo Horizonte. Older adults with low back pain symptoms were identified by health professionals (physicians, physiotherapists, occupational therapists, among others) of the public or private service, and were directed to the BACE-B research team. Those who sought the trained team of BACE-B researchers were screened and invited to participate in the study.

The BACE-B study included older adults with a new episode of LBP. LBP was defined as of complaints of pain, tension or stiffness in the region between the last ribs and the gluteal line, with or without irradiation of pain to the lower limbs (LL)²²22. Dionne CE, Dunn KM, Croft PR, Nachemson AL, Buchbinder R, Walker BF, Wyatt M, Cassidy JD, Rossignol M, Leboeuf-Yde C, Hartvigsen J, Leino-Arjas P, Latza U, Reis S, Gil Del Real MT, Kovacs FM, Oberg B, Cedraschi C, Bouter LM, Koes BW, Picavet HS, Van Tulder MW, Burton K, Foster NE, Macfarlane GJ, Thomas E, Underwood M, Waddell G, Shekelle P, Volinn E, Von KM. A consensus approach toward the standardization of back pain definitions for use in prevalence studies. Spine (Phila Pa 1976) 2008; 33(1):95-103.. A new episode of LBP was defined as participants not seeking treatment for LBP in the six months preceding study participation²¹21. Scheele J, Luijsterburg PA, Ferreira ML, Maher CG, Pereira L, Peul WC, Van Tulder MW, Bohnen AM, Berger MY, Bierma-Zeinstra SM, Koes BW. Back complaints in the elders (BACE); design of cohort studies in primary care: an international consortium. BMC Musculoskelet Disord [periódico na Internet] 2011[acessado 2011 Out 23]; 12:[cerca de 9p. ]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182961/pdf/1471-2474-12-193.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... . In turn, acute symptoms were defined as an LBP crisis in the maximum period of six weeks before the baseline assessment²³23. Koes B, van TM. Acute low back pain. Am Fam Physician 2006; 74(5):803-805.. Only older adults with these criteria were included in the BACE-B study.

Participants with visual, motor and hearing impairment or cognitive dysfunctions²⁴24. Bertolucci PH, Brucki SMD, Campacci SR, Juliano Y. O mini-exame do estado mental em uma população geral: impacto da escolaridade. Arq Neuropsiquiatr [periódico na Internet] 1994 [acessado 2013 Maio 01]; 52(1):[cerca de 7p.]. Disponível em: http://www.scielo.br/pdf/anp/v52n1/01.pdf
http://www.scielo.br/pdf/anp/v52n1/01.pd... that could influence their response to questionnaires or performance of physical and functional tests adequately were excluded.

The sample of this study consisted of participants from the baseline of BACE-B aged ≥ 65 years. The selection of this sample considered three aspects: (1) the chronological framework proposed by the WHO that considers older people as those aged 65 or over; (2) easy comparison with international data; (3) the lower variability of the sample due to its greater homogeneity regarding age.

Measurement and procedure tools

Participants evaluated the inclusion/exclusion criteria that agreed to participate in the study, signed the informed consent form and were included in the study. All were submitted to a standardized, structured and multidimensional questionnaire for characterization of the sample and evaluation of LBP complaints. They also performed a physical and functional examination, as per the BACE consortium’s guidelines. All detailed procedures have been previously described and published in the BACE²¹21. Scheele J, Luijsterburg PA, Ferreira ML, Maher CG, Pereira L, Peul WC, Van Tulder MW, Bohnen AM, Berger MY, Bierma-Zeinstra SM, Koes BW. Back complaints in the elders (BACE); design of cohort studies in primary care: an international consortium. BMC Musculoskelet Disord [periódico na Internet] 2011[acessado 2011 Out 23]; 12:[cerca de 9p. ]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182961/pdf/1471-2474-12-193.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... consortium’s protocol.

The outcome measure of this study was LBP-related disability assessed using the Roland Morris Disability Questionnaire (RMDQ), which consists of 24 items related to the influence of back pains during daily activities and measures the level of disability associated with LBP. The RMDQ score ranges from 0 to 24, with higher scores indicating a worse level of disability. This questionnaire shows good test-retest reliability and among examiners (r = 0.88 and 0.86, respectively)²⁵25. Nusbaum L, Natour J, Ferraz M, Goldenberg J. Translation, adaptation and validation of the Roland-Morris questionnaire - Brazil Roland-Morris. Braz J Med Biol Res 2001; 34(2):203-210.,²⁶26. Roland M, Morris R. A study of the natural history of back pain. Part I: development of a reliable and sensitive measure of disability in low-back pain. Spine (Phila Pa 1976) 1983; 8(2):141-144..

The biopsychosocial factors potentially eligible for association with disability were selected from baseline assessment according to clinical or theoretical relevance. Following the rationale of the biopsychosocial approach for LBP, these factors were categorized as follows: biological, psychological, and sociodemographic/lifestyle factors¹⁴14. Waddell G. Biopsychosocial analysis of low back pain. Baillieres Clin Rheumatol 1992; 6(3):523-557..

Biological factors

(1) LBP intensity in the last week, evaluated by the Numeric Rating Scale (NRS), with a score ranging from 0 (no pain) to 10 (maximum pain); (2) complaints of pain irradiation to LL (yes/no); (3) report of pain during active trunk movements – anterior flexion, lateral flexion and trunk rotation (yes/no); (4) trouble sleeping because of low back pain (yes/no); (5) anterior trunk flexibility assessed by the finger-to-floor distance (FFD) test, which measures the distance in cm from the third finger of one hand to the floor during the maximum anterior flexion of the trunk; (6) positive Lasègue test (yes/no); (7) low back morning stiffness (yes/no); (8) functional mobility, as gauged by the Timed up and Go (TUG), which measures the time in seconds for the elderly to perform the task of getting up from the seated position, to walk three meters, to turn around, to return to the chair and sit down again. Times more significant than 12-14 seconds are associated with an increased risk of falls in the elderly²⁷27. Podsiadlo D, Richardoson S. The timed Up & Go: a test of basic functional mobility for frail elderly persons. J Am Geriatr Soc 1991; 39(2):142-148.; (9) number of comorbidities, evaluated by self-administered comorbidity questionnaire (SCQ), considering the following morbidities: heart disease, systemic arterial hypertension, pulmonary disease, diabetes, stomach disease, kidney disease, liver disease, blood diseases, cancer, depression, osteoarthritis (hip, knee or hand), rheumatoid arthritis, complaints of pain in the shoulders and cervical spine²⁸28. Sangha O, Stucki G, Liang MH, Fossel AH, Katz JN. The Self-Administered Comorbidity Questionnaire: a new method to assess comorbidity for clinical and health services research. Arthritis Rheum 2003; 49(2):156-163.; (10) physical health, evaluated by the physical realm of the Short Form Health Status Questionnaire-36 (SF-36), consisting of generic questions of physical health status, with a score ranging from 0 to 100, with the lowest values showing worse results²⁹29. Ciconelli RM, Ferraz MB, Santos MS, Meinão I, Quaresma MR. Tradução para língua portuguesa e validação do questionário genérico de avaliação de qualidade de vida SF-36 (Brasil SF-36). Rev Bras Reumatol 1999; 39(3):143-150.; (11) previous history of LBP (yes/no); (12) body mass index (BMI); (13) reported use of medication for LBP in the last 6 weeks (yes/no); (14) visit to a specialist doctor because of LBP in the last 6 weeks (yes/no); (15) low back imaging tests in the last 6 weeks (yes/no).

Psychological factors

(1) Kinesiophobia, evaluated by the Fear-Avoidance Beliefs Questionnaire, which measures the fear, beliefs and avoidance behaviors of people with LBP. The physical activity subscale, used in this investigation, consists of 4 items, with a score from 0 to 24, where the highest values evidence the worst results³⁰30. Abreu AM, Faria CD, Cardoso SM, Teixeira-Salmela LF. Versão brasileira do Fear Avoidance Beliefs Questionnaire. Cad Saude Publica 2008; 24(3):615-623.,³¹31. Coudeyre E, Tubach F, Rannou F, Baron G, Coriat F, Brin S, Revel M, Poiraudeau S. Fear-avoidance beliefs about back pain in patients with acute LBP. Clin J Pain 2007; 23(8):720-725.; (2) depressive symptoms, evaluated by the Depression Scale Center for Epidemiological Studies (CES-D) that addresses issues about mood, somatic symptoms, interactions, and motor functioning. This scale considers symptoms experienced in the last week and the final score ranges from 0 to 60 points, with a cutoff point > 11 considered positive for depressive symptoms in the Brazilian population³²32. Batistoni SST, Neri AL, Dalziel WB. Validade da escala de depressão do Center for Epidemiological Studies entre idosos brasileiros. Rev Saude Publica 2007; 41(4):598-605.; (3) mental health, evaluated by the mental realm of the Short Form Health Status Questionnaire-36 (SF-36), composed of generic questions of mental health status, with a score ranging from 0 to 100, with the lowest values representing worse results²⁹29. Ciconelli RM, Ferraz MB, Santos MS, Meinão I, Quaresma MR. Tradução para língua portuguesa e validação do questionário genérico de avaliação de qualidade de vida SF-36 (Brasil SF-36). Rev Bras Reumatol 1999; 39(3):143-150.; and (4) falls self-efficacy, evaluated through the Falls Efficacy Scale - International (FES-I) questionnaire, which registers the elderly’s concern with fall during the performance of 16 activities; it has scores ranging from 16 to 64, and the highest score represents a lower sense of self-efficacy in falls³³33. Camargos FF, Dias RC, Dias JM, Freire MT. Cross-cultural adaptation and evaluation of the psychometric properties of the Falls Efficacy Scale-International Among Elderly Brazilians (FES-I-BRAZIL). Rev Bras Fisioter 2010; 14(3):237-243..

Sociodemographic factors and lifestyle

(1) Age in years; (2) gender (male/female); (3) marital status (categories: married/ common-law marriage, single/divorced, widower); (4) schooling level (categories: low, medium and high); (5) income (categories: low – up to 2 minimum wages, medium – from 2 to 5 minimum wages, and high – 5 or more minimum wages); (6) alcohol use (yes/no); (7) tobacco use (yes/no); (8) paid work (yes/no) and (9) physical activity level in the last week, using the International Physical Activity Questionnaire (IPAQ), which assesses people’s level of physical activity in various activities, including those carried out during leisure time, such as traveling from one place to another, domestic chores and occupational activities, and individuals are categorized into three activity levels: inactive, moderately active and active (IPAQ)³⁴34. Craig CL, Marshall AL, Sjostrom M, Bauman AE, Booth ML, Ainsworth BE, Pratt M, Ekelund U, Yngve A, Sallis JF, Oja P. International physical activity questionnaire: 12-country reliability and validity. Med Sci Sports Exerc 2003; 35(8):1381-1395..

Statistical review

Descriptive statistics were used to report the sample characterization data, considering measures of central tendency and frequency of outcomes.

A multivariate linear regression model was constructed to analyze the factors associated with LBP disability. Initially, a bivariate analysis was performed to examine the existence of relationships of the (continuous and dichotomous) independent variables with the variable of disability (outcome). Then, several stepwise multiple linear regression models were used to define the best combination of variables in the final model. The potential explanatory variables were selected by theoretical criteria and included in the regression models as per statistical criteria. All variables with statistical significance (p≤0.2) in the bivariate analysis were inserted into the regression model, except for the variables age, gender, schooling, which were included in the regression model regardless of the existence of a significant correlation in the bivariate analysis.

The final regression model was defined after verifying and respecting the following assumptions: the presence of a linear relationship between the independent variables and the dependent variable, the independence of the explanatory variables (associated factors); absence of multicollinearity, verified by means of tolerance and the variance inflation factor (VIF); constant variance of errors (homoscedasticity of errors); independent distribution of errors (Durbin-Watson test) and residue normality (graphical analysis and Kolmogorov-Smirnov normality test).

The sample size was calculated with the following formula: n = 10 x (K + 1), where “K” is the number of explanatory variables included in the multiple regression model and “n” is the size of the study sample. Thus, a minimum sample size of 300 participants was required to perform multiple linear regression analyses with up to 30 explanatory variables. All analyses were performed by the Statistical Package for the Social Sciences (SPSS) for Windows (Version 22.0), and the level of significance was set at 5%.

Results

Elderly Participants from the baseline of the BACE-B cohort were included in our analyses. Figure 1 illustrates the selection process of the participants for this research. The sample consisted of 386 older adults with a mean age of 71.6 ± 4.2 years, mostly females (84.5%), with low levels of schooling (67.6%) and income (71%). Regarding the complaint-related characteristics, older adults had a mean disability of 13.7 (± 5.7) through RMDQ, mean pain intensity of 7.1 (± 2.6) through NRS and mean duration of the new LBP episode of 18.9 (± 12.5) days. The descriptive characteristics of the sample are shown in Tables 1 and 2.

The calculated multiple linear regression model enables the prediction of disability levels based on the interaction of multiple explanatory variables. The regression equation found in the final model was [F (10, 366) = 48.813, p <0.000], with an R²2. Klijs B, Nusselder WJ, Looman CW, Mackenbach JP. Contribution of chronic disease to the burden of disability. PLoS One [periódico na Internet] 2011 [acessado 2015 Jan 16]; 6(9):[cerca de 8p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC 3178640/pdf/pone.0025325.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... of 0.622. Thus, approximately 62% of disability variability was explained by the 10 predictors of the regression model. The predictive factors of higher pain intensity (0.7%), trouble sleeping because of LBP (2.8%) occurrence of low back morning stiffness (3.4%) worse functional mobility (2.5%), worse physical health (13.9%), higher levels of BMI (1.9%), kinesiophobia (0.8%), low falls self-efficacy (0.6%), worse mental health (35%) and female gender (0.6%) significantly influenced the disability in the sample investigated. Increased disability levels were associated with worse performance in the biopsychosocial health measures scores in the final multiple linear regression model (Table 3).

Discussion

This cross-sectional study analyzed the association of biopsychosocial factors with disability in seniors older adults with a new episode of acute LBP. Multiple predictive factors were associated with disability in the investigated sample. The multiple regression model identified ten predictive factors that together accounted for 62.2% of disability variability. These data highlight the multifactorial characteristic of disability in older adults with LBP and corroborates data from previous studies on disability in the general population with individuals affected by LBP³⁵35. Frymoyer JW. Predicting disability from low back pain. Clin Orthop Relat Res 1992; 279:101-109.,³⁶36. Stewart WJ, Ng N, Peltzer K, Yawson A, Biritwum R, Maximova T, Wu F, Arokiasamy P, Kowal P, Chatterji S. Risk Factors and Disability Associated with Low Back Pain in Older Adults in Low- and Middle-Income Countries. Results from the WHO Study on Global AGEing and Adult Health (SAGE). PLoS One [periódico na Internet] 2015 [acessado 2016 Abr 27]; 10(6):[cerca de 21p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456393/pdf/pone.0127880.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... .

Recently, a study conducted by the WHO – Study on Global AGEing and Adult Health (SAGE) assessed risk factors for disability in adults and seniors with LBP. The authors included more than 30,000 participants (50.2% aged 50-59 years and 49.8% aged 60 years or older) with LBP in the last 30 days. The risk factors for disability identified were being female, low schooling, a more significant number of comorbidities, higher pain intensity, increased age and low level of physical activity³⁶36. Stewart WJ, Ng N, Peltzer K, Yawson A, Biritwum R, Maximova T, Wu F, Arokiasamy P, Kowal P, Chatterji S. Risk Factors and Disability Associated with Low Back Pain in Older Adults in Low- and Middle-Income Countries. Results from the WHO Study on Global AGEing and Adult Health (SAGE). PLoS One [periódico na Internet] 2015 [acessado 2016 Abr 27]; 10(6):[cerca de 21p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456393/pdf/pone.0127880.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... . These data corroborate the results of our study regarding the multidimensionality of disability.

However, differences between the types of factors associated with a disability differ between studies. In this study, disability was not associated with schooling, comorbidities, age and level of physical activity. Differences in the sample profile and questionnaire used to measure disability may warrant such differences. Stewart et al. (2015) used a generic WHO Disability Assessment Schedule (WHODAS) to assess disability in a mixed population (adults and seniors) with chronic and acute LBP³⁶36. Stewart WJ, Ng N, Peltzer K, Yawson A, Biritwum R, Maximova T, Wu F, Arokiasamy P, Kowal P, Chatterji S. Risk Factors and Disability Associated with Low Back Pain in Older Adults in Low- and Middle-Income Countries. Results from the WHO Study on Global AGEing and Adult Health (SAGE). PLoS One [periódico na Internet] 2015 [acessado 2016 Abr 27]; 10(6):[cerca de 21p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456393/pdf/pone.0127880.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... , while in this study, a specific questionnaire was used to measure disability only in older adults (65 years or older) with acute LBP²⁵25. Nusbaum L, Natour J, Ferraz M, Goldenberg J. Translation, adaptation and validation of the Roland-Morris questionnaire - Brazil Roland-Morris. Braz J Med Biol Res 2001; 34(2):203-210.,²⁶26. Roland M, Morris R. A study of the natural history of back pain. Part I: development of a reliable and sensitive measure of disability in low-back pain. Spine (Phila Pa 1976) 1983; 8(2):141-144..

Our results showed that higher levels of disability were associated with higher pain intensity through NRS, corroborating similar results from other studies¹⁹19. Pensri P, Janwantanakul P, Worakul P, Sinsongsook T. Biopsychosocial factors and perceived disability in saleswomen with concurrent low back pain. Saf Health Work 2010; 1(2):149-157.,³⁶36. Stewart WJ, Ng N, Peltzer K, Yawson A, Biritwum R, Maximova T, Wu F, Arokiasamy P, Kowal P, Chatterji S. Risk Factors and Disability Associated with Low Back Pain in Older Adults in Low- and Middle-Income Countries. Results from the WHO Study on Global AGEing and Adult Health (SAGE). PLoS One [periódico na Internet] 2015 [acessado 2016 Abr 27]; 10(6):[cerca de 21p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456393/pdf/pone.0127880.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... ,³⁷37. Weiner DK, Rudy TE, Kim YS, Golla S. Do medical factors predict disability in older adults with persistent low back pain? Pain 2004; 112(1-2):214-220.. patients with more severe LBP may experience greater pain intensity and, consequently, higher levels of disability. This hypothesis is corroborated by the study by Weiner et al.³⁷37. Weiner DK, Rudy TE, Kim YS, Golla S. Do medical factors predict disability in older adults with persistent low back pain? Pain 2004; 112(1-2):214-220., who found a correlation of disability with higher intensity (R = 0.370, p = 0.001) and pain duration (r = -360, p = 003) when evaluating 100 older adults (mean age of 74.3 years) of the chronic LBP community. In this sample, mean values of disability (13.7 ± 5.7) and pain (7.1 ± 2.6) were higher than other studies on LBP with a specific population of the elderly. Jarvik et al.³⁸38. Jarvik JG, Comstock BA, Heagerty PJ, Turner JA, Sullivan SD, Shi X, Nerenz DR, Nedeljkovic SS, Kessler L, James K, Friedly JL, Bresnahan BW, Bauer Z, Avins AL, Deyo RA. Back pain in seniors: the Back pain Outcomes using Longitudinal Data (BOLD) cohort baseline data. BMC Musculoskelet Disord [periódico na Internet] 2014 [acessado 2015 Nov 10]; 15:[cerca de 11p. ]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4021204/pdf/1471-2474-15-134.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... found mean LBP intensity of 5.0 (± 2.8) through NRS and mean disability of 9.5 (± 6.4) through RMDQ in an investigation with 5,239 American older adults (mean age of 73.8 ± 6.9 years) with LBP. Scheele et al.³⁹39. Scheele J, Enthoven WT, Bierma-Zeinstra SM, Peul WC, Van Tulder MW, Bohnen AM, Berger MY, Koes BW, Luijsterburg PA. Characteristics of older patients with back pain in general practice: BACE cohort study. Eur J Pain 2014; 18(2):279-287. found mean LBP intensity of 4.0 (± 2.8) through NRS and mean disability of 9.8 (± 5.8) through RMDQ in a study of 675 senior Dutch subjects (mean age of 66.4 ± 7.6 years) with a new episode of LBP.

Differences in sample characteristics may warrant such data. Only older adults with an acute LBP episode were included in this study, while seniors with subacute and chronic LBP were also included in the studies with American and Dutch elderly. Usually, patients with subacute and chronic LBP have symptoms of pain and disability of lower intensity than those with acute LBP⁴4. Costa LCM, Maher CG, Hancock MJ, McAuley JH, Herbert RD, Costa LO. The prognosis of acute and persistent low-back pain: a meta-analysis. CMAJ 2012; 184(11):E613-E624..

Contrary to the results of this study, Stewart et al.³⁶36. Stewart WJ, Ng N, Peltzer K, Yawson A, Biritwum R, Maximova T, Wu F, Arokiasamy P, Kowal P, Chatterji S. Risk Factors and Disability Associated with Low Back Pain in Older Adults in Low- and Middle-Income Countries. Results from the WHO Study on Global AGEing and Adult Health (SAGE). PLoS One [periódico na Internet] 2015 [acessado 2016 Abr 27]; 10(6):[cerca de 21p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456393/pdf/pone.0127880.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... did not find an association between obesity and disability, but these authors evaluated obesity using waist circumference (OR = 0.3; p > 0.1). Weiner et al.³⁷37. Weiner DK, Rudy TE, Kim YS, Golla S. Do medical factors predict disability in older adults with persistent low back pain? Pain 2004; 112(1-2):214-220. also found no association of BMI (r = 0.030, p = 0.270) with disability. This study contradicts these data by evidencing the association of BMI and disability in the sample of older adults with acute LBP investigated. In this aspect, it is essential to highlight that the association of BMI with LBP in older adults, while not specifically with disability due to LBP, has already been described⁹9. Rudy TE, Weiner DK, Lieber SJ, Slaboda J, Boston JR. The impact of chronic low back pain on older adults: a comparative study of patients and controls. Pain 2007; 131(3):293-301.,¹⁰10. Weiner DK, Haggerty CL, Kritchevsky SB, Harris T, Simonsick EM, Nevitt M, Newman A. How does low back pain impact physical function in independent, well-functioning older adults? Evidence from the Health ABC Cohort and implications for the future. Pain Med 2003; 4(4):311-320.. These contradictions suggest that the relationship of obesity with LBP is still controversial in the older population.

The variable female gender was associated with disability and remained in the final regression model. Women are known to have more health problems and disabilities. Murtagh & Hubert (2004) described a higher prevalence of health-related disabilities in women than in older men⁴⁰40. Murtagh KN, Hubert HB. Gender differences in physical disability among an elderly cohort. Am J Public Health 2004; 94(8):1406-1411.. Chenot et al. (2008) found a higher severity of LBP in women and showed the association of women with low functional capacity and worse prognosis of LBP, including in seniors, who represented 22% of their sample⁴¹41. Chenot JF, Becker A, Leonhardt C, Keller S, Donner-Banzhoff N, Hildebrandt J, Basler HD, Baum E, Kochen MM, Pfingsten M. Sex differences in presentation, course, and management of low back pain in primary care. Clin J Pain 2008; 24(7):578-584.. Thus, we can infer that being female is a negative trait in the population affected by LBP.

The results of this study also showed an association of kinesiophobia with a disability and agree with data from previous studies evaluating older adults with chronic LBP⁴²42. Basler HD, Luckmann J, Wolf U, Quint S. Fear-avoidance beliefs, physical activity, and disability in elderly individuals with chronic low back pain and healthy controls. Clin J Pain 2008; 24(7):604-610.

43. Champagne A, Prince F, Bouffard V, Lafond D. Balance, Falls-Related Self-Efficacy, and Psychological Factors amongst Older Women with Chronic Low Back Pain: A Preliminary Case-Control Study. Rehabil Res Pract [periódico na Internet] 2012 [acessado 2016 Mar 29]; 2012:[cerca de 8p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3425864/pdf/RERP2012-430374.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... -⁴⁴44. Sions JM, Hicks GE. Fear-avoidance beliefs are associated with disability in older American adults with low back pain. Phys Ther 2011; 91(4):525-534. and adults with acute LBP³¹31. Coudeyre E, Tubach F, Rannou F, Baron G, Coriat F, Brin S, Revel M, Poiraudeau S. Fear-avoidance beliefs about back pain in patients with acute LBP. Clin J Pain 2007; 23(8):720-725.. This association between kinesiophobia and disability can be better understood based on the following assumption: the negative experience with pain induces the fear of the onset/increase of pain resulting from movement and, thus, individuals avoid movement/activity, perpetuating the condition of disability⁴³43. Champagne A, Prince F, Bouffard V, Lafond D. Balance, Falls-Related Self-Efficacy, and Psychological Factors amongst Older Women with Chronic Low Back Pain: A Preliminary Case-Control Study. Rehabil Res Pract [periódico na Internet] 2012 [acessado 2016 Mar 29]; 2012:[cerca de 8p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3425864/pdf/RERP2012-430374.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... . In this perspective, we can suppose that seniors with LBP and kinesiophobic behavior reduce mobility and daily activities, favoring social isolation and incapacities.

Hall et al.⁴⁵45. Hall AM, Kamper SJ, Maher CG, Latimer J, Ferreira ML, Nicholas MK. Symptoms of depression and stress mediate the effect of pain on disability. Pain 2011; 152(5):1044-1051. showed that approximately 30% of the relationship between LBP and disability are mediated by psychological symptoms. The authors concluded that this relationship also depends on other factors, considering that only 30% of disability variability was explained by psychological questions. Our results corroborate this finding, because although the variable depressive symptoms (evaluated by the CES-D) did not remain in the final regression model, the worst mental health condition (measured by SF-36) was the predictor that mainly explained disability, showing the existence of a significant association of psychological characteristics with the disability in the sample investigated. A vicious cycle is being hypothesized, and the presence of LBP and its disabilities increase mental suffering, influencing the worsening of mental health status. On the other hand, the older adult with a worse state of mental health may have more difficulties in confronting and solving LBP, perceiving higher levels of disability when compared to those without emotional changes⁴⁶46. Rippentrop EA, Altmaier EM, Chen JJ, Found EM, Keffala VJ. The relationship between religion/spirituality and physical health, mental health, and pain in a chronic pain population. Pain 2005; 116(3):311-321..

Increased disability was associated with decreased falls self-efficacy (FES-I). Verma & Pal⁴⁷47. Verma S, Pal BP. Correlation Between Pain, Fear of Falling and Disability in Low Back Pain. Ann Rehabil Med 2015;39(5):816-820. studied a sample of 100 patients with acute LBP (last six weeks), with age ranging from 40 to 73 years, and also found an association between disability and falls self-efficacy. The authors conclude that increased disability in LBP patients was associated with a lower sense of falls self-efficacy⁴⁷47. Verma S, Pal BP. Correlation Between Pain, Fear of Falling and Disability in Low Back Pain. Ann Rehabil Med 2015;39(5):816-820.. Functional mobility, as assessed by TUG, also showed a negative and significant association with disability, reinforcing data from previous studies that found an association between LBP and decreased functional mobility in older adults⁴³43. Champagne A, Prince F, Bouffard V, Lafond D. Balance, Falls-Related Self-Efficacy, and Psychological Factors amongst Older Women with Chronic Low Back Pain: A Preliminary Case-Control Study. Rehabil Res Pract [periódico na Internet] 2012 [acessado 2016 Mar 29]; 2012:[cerca de 8p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3425864/pdf/RERP2012-430374.pdf
https://www.ncbi.nlm.nih.gov/pmc/article... ,⁴⁸48. Queiroz BZ, Pereira DS, Rosa NM, Lopes RA, Felicio DC, Pereira DG, Dias JM, Dias RC, Pereira LS. Functional performance and plasma cytokine levels in elderly women with and without low back pain. J Back Musculoskelet Rehabil 2015; 28(2):343-349..

Our results evidenced the association of morning stiffness and altered sleep due to pain with increased disability. Previous studies performed in the general population have shown an association of sleep quality patterns⁴⁹49. Alsaadi SM, McAuley JH, Hush JM, Maher CG. Prevalence of sleep disturbance in patients with low back pain. Eur Spine J 2011; 20(5):737-743. and the occurrence of morning low back stiffness with a worse clinical condition in patients with LBP⁵⁰50. Scheele J, de Schepper EI, van Meurs JB, Hofman A, Koes BW, Luijsterburg PA, Bierma-Zeinstra SM. Association between spinal morning stiffness and lumbar disc degeneration: the Rotterdam Study. Osteoarthritis Cartilage 2012; 20(9):982-987.. Frymoyer et al. (1992) emphasized the importance of physical factors in the prediction of disability in patients with LBP³⁵35. Frymoyer JW. Predicting disability from low back pain. Clin Orthop Relat Res 1992; 279:101-109.; however, we did not find specific studies on sleep disorders or morning stiffness and their relationships specifically with disability in older adults with LBP, hindering their comparison with our results.

Finalizing the analysis of our results, the physical health status, measured by the SF-36 physical realm, was significantly associated with disability. Previous data that indicate the influence of health status on LBP disability are consistent with this result⁹9. Rudy TE, Weiner DK, Lieber SJ, Slaboda J, Boston JR. The impact of chronic low back pain on older adults: a comparative study of patients and controls. Pain 2007; 131(3):293-301.,⁴⁶46. Rippentrop EA, Altmaier EM, Chen JJ, Found EM, Keffala VJ. The relationship between religion/spirituality and physical health, mental health, and pain in a chronic pain population. Pain 2005; 116(3):311-321.. However, it is essential to note that the available literature on LBP in the general population has shown meaningful participation of psychological and social issues in detriment of clinical and biological issues¹⁸18. Hulla R, Moomey M, Garner T, Ray C, Gatchel RJ. Biopsychosocial Characteristics, Using a New Functional Measure of Balance, of an Elderly Population with CLBP. Healthcare (Basel) [periódico na Internet] 2016 [acessado 2017 Mar 9]; 4(3):[cerca de 9p.]. Disponível em: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5041060/pdf/healthcare-04-00059.pdf
https://www.ncbi.nlm.nih.gov/pmc/article...

19. Pensri P, Janwantanakul P, Worakul P, Sinsongsook T. Biopsychosocial factors and perceived disability in saleswomen with concurrent low back pain. Saf Health Work 2010; 1(2):149-157.-²⁰20. Koenig AL, Kupper AE, Skidmore JR, Murphy KM. Biopsychosocial functioning and pain self-efficacy in chronic low back pain patients. J Rehabil Res Dev 2014; 51(8):1277-1286.,³⁷37. Weiner DK, Rudy TE, Kim YS, Golla S. Do medical factors predict disability in older adults with persistent low back pain? Pain 2004; 112(1-2):214-220.,⁴⁴44. Sions JM, Hicks GE. Fear-avoidance beliefs are associated with disability in older American adults with low back pain. Phys Ther 2011; 91(4):525-534.. This is also evident in this study since several biological factors did not show a significant association with disability.

This study presented some limitations that will be discussed below: (1) Participants were recruited consecutively (not randomly), which may contribute to sample selection bias and compromise the generalization of results. Characteristics such as age, gender, the severity of symptoms, access to health services, availability and interest of participants may have influenced the recruitment of participants and produced discrepancies in the sample’s representativeness. For example, the sample of this study consisted mostly of women and, even considering the event of feminization of old age, the proportion of women was higher than the expected demographic distribution for the population of older women and men. Thus, there is a need for caution in the generalization of our results. (2) Items of the questionnaire used to measure disability showed similarity with some explanatory factors or items of questionnaires used to measure them.

In this aspect, it is essential to note that, while having a certain similarity, the questionnaires used in this study measure different constructs, show different psychometric characteristics and scores, with validity and reliability already determined in previous publications. Moreover, we used the total scores of the instruments, which minimizes problems with the similarity of items isolated from the questionnaires. We also considered the possibility of multicollinearity during the statistical analysis, and no evidence of a violation of this assumption was found. (3) In view of the cross-sectional design of this study, it is crucial to consider the possibility of reverse causality, considering that critical factors can be modified by the existence of the disease, and it is not possible to determine what occurred first in cross-sectional studies – whether the exposure or the outcome. Thus, interpretation of results and discussions presented should be understood only as a verification of the association between the variables and cannot be confused with the cause-effect relationship.

Conclusions

This study investigated multiple biopsychosocial factors and their associations with disability in an exclusive sample of older adults with a new episode of acute LBP. We describe the multifactorial interaction of biological, psychological and demographic characteristics with disability, showing discussions and comparisons with available literature. The exploration of this theme in a population commonly excluded from LBP research is innovative and highlights the importance of LBP in the population. We conclude that disability in the older adult with acute LBP is multifactorial and is associated with worse performance in biopsychosocial health measures. Our results contribute to increased scientific knowledge and can be used as a subsidy by health professionals to approach disability in seniors with LBP. However, longitudinal and prospective studies are needed to validate hypotheses and test cause and effect relationships for disability in older adults with LBP.

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