ABSTRACT:

Objective:

To estimate the prevalence of asthma medical diagnosis among the adult Brazilian population (aged ≥ 18 years).

Methods:

This is a cross-sectional, population-based study from the 2013 National Health Survey (NHS); it is a sampling cluster process with three stages of selection: census tracts, households, and individuals. The prevalence and 95% confidence interval for the outcome "asthma medical diagnosis" reported by the interviewed subjects were calculated, besides its distribution according to demographic and socioeconomic variables, macroregions, and urban or rural area of the country. Management of the disease was also evaluated among those who reported asthma medical diagnosis and the analyses were weighted.

Results:

A total of 60,202 adults were interviewed. The prevalence of asthma medical diagnosis was 4.4% (95%CI 4.1 - 4.7), and it was higher among the female subjects, the white skin-colored subjects, those with higher educational level, and those who lived in the south of Brazil. Among those who reported asthma medical diagnosis, a high percentage of asthma attacks were seen in the last 12 months, with around 80% using medication and about 15% referring severe limitation to their daily activities.

Conclusions:

Although it seems there is asthma diagnosis stability in the country when compared with other researches, we still need public policies for improving the disease management.

Keywords:
Asthma; Diagnosis; Prevalence; Health surveys; Chronic disease; Cross-sectional studies.

INTRODUCTION

Most of the studies about asthma have been conducted in childhood and adolescence through surveys such as the International Study of Asthma and Allergies (ISAAC)¹1. Mallol J, Crane J, von Mutius E, Odhiambo J, Keil U, Stewart A, et al. The International Study of Asthma and Allergies in Childhood (ISAAC) Phase Three: a global synthesis. Allergol Immunopathol 2013 ;41(2): 73-85. and the Global Initiative for Asthma (GINA)²2. Global Initiative for Asthma. Pocket guide for asthma manegement and prevention (for adults and children older than 5 years): Global Initiative for asthma. 2014 update.. The European Community Respiratory Research(ECRHS)³3. Variations in the prevalence of respiratory symptoms, self-reported asthma attacks, and use of asthma medication in the European Community Respiratory Health Survey (ECRHS). European Respir J 1996; 9(4): 687-95. and the World Health Survey (WHS), from 2001 to 2003⁴4. Szwarcwald CL, Viacava F. Pesquisa Mundial de Saúde: aspectos metodológicos e articulação com a Organização Mundial da Saúde. Rev Bras Epidemiol 2008; 11 (Suppl 1): 58-66. ⁵5. To T, Stanojevic S, Moores G, Gershon AS, Bateman ED, Cruz AA, et al. Global asthma prevalence in adults: findings from the cross-sectional world health survey. BMC Public Health 2012; 12: 204., evaluated the asthma prevalence in adults from several countries. The WHS showed that the global prevalence of asthma self-report diagnosis was estimated to be 4.3% (95%CI 4.2 - 4.4). It also evaluated the disease load, which showed that 1 in every 2 subjects with clinical asthma (medical diagnosis and/or treatment any time in life or in the last 2 weeks) reported an attack in the last 12 months, and 1 in 5 never received any treatment in life⁵5. To T, Stanojevic S, Moores G, Gershon AS, Bateman ED, Cruz AA, et al. Global asthma prevalence in adults: findings from the cross-sectional world health survey. BMC Public Health 2012; 12: 204..

In Brazil, one of the WHS participating countries, the prevalence of asthma self-report diagnosis was around 12%, considering the age range of adults aged ≥ 18 years, which is higher than the global prevalence estimated by the WHS. Among the countries with mean gross national income adjusted for purchasing power parity (GNI PPP), the Brazilian prevalence was the highest, although it was lower when compared with some other countries with high GNI PPP⁶6. Sembajwe G, Cifuentes M, Tak SW, Kriebel D, Gore R, Punnett L. National income, self-reported wheezing and asthma diagnosis from the World Health Survey. European Respir J. 2010; 35(2): 279-86.. Unlike the WHS estimative, another population-based research carried out in Brazil during three moments (1998, 2003, and 2008), the Household Sample National Survey (PNAD), including adults aged ≥ 20 years, showed a prevalence of asthma medical diagnosis in the studied years of 4.1% in 1998 and 2003 and 4.0% in 2008⁷7. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostra de Domicílios: Um panorama da saúde no Brasil - acesso e utilização de serviço, condições de saúde e fatores de risco e proteção à saúde, 2008. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2010. Disponível em: Disponível em: http://bvsms.saude.gov.br/bvs/publicacoes/pnad_panorama_saude_brasil.pdf . (Acessado em 2 de junho de 2015).
http://bvsms.saude.gov.br/bvs/publicacoe... .

This article aimed at estimating the prevalence of asthma medical diagnosis in a sample that represents the adult population of a country and the disease management.

METHODS

This investigation is a cross-sectional, population-based study. It used the data collected in the 2013 National Health Survey (NHS), conducted by the Instituto Brasileiro de Geografia e Estatística (IBGE), with subjects aged ≥ 18 years. The calculation of sample size considered information from the 2008 PNAD health supplement. The minimum size of the sample was 1,800 households per Federation Unit (FU), and the chosen sample was composed of 81,167 households⁸8. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde: 2013. Percepção do estado de saúde, estilos de vida e doenças crônicas. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística 2014. Disponível em: ftp://ftp.ibge.gov.br/PNS/2013/pns2013.pdf. (Acessado em 2 de junho de 2015).. It was a NHS cluster sampling process with three stages of selections: census tracts, households, and individuals. Only one subject aged 18 years or older of each household was chosen for the sample through a simple randomized process. Specific variables based on the probability of being chosen to be part of the sample were used. This process ensured representativeness for Brazil, macroregions, FUs, and some metropolitan regions. Detailed information about the sampling process can be seen in the NHS technical report⁸8. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde: 2013. Percepção do estado de saúde, estilos de vida e doenças crônicas. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística 2014. Disponível em: ftp://ftp.ibge.gov.br/PNS/2013/pns2013.pdf. (Acessado em 2 de junho de 2015)..

The questionnaire applied to the chosen residents included themes such as self-perception of health, violence and accidents, woman and child's health, elderly health, physical activity, smoking, and nontransmitted chronic diseases, among others. The entire questionnaire was applied with the use of personal digital assistants (PDA)⁸8. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde: 2013. Percepção do estado de saúde, estilos de vida e doenças crônicas. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística 2014. Disponível em: ftp://ftp.ibge.gov.br/PNS/2013/pns2013.pdf. (Acessado em 2 de junho de 2015)..

The main outcome from this article was asthma medical diagnosis that was evaluated using the following question: "Has any physician provided you asthma diagnosis (or asthmatic bronchitis)?". The presence of asthma crisis was also evaluated in the last 12 months (yes/no) among subjects who answered "yes" for the previous question. Moreover, in this subgroup, the use of medications for asthma (yes/no) and degree of limitation in the daily life activities owing to asthma were also analyzed and categorized as: without limitation (including "light or moderate") or very severe limitation (including "severe").

The exposure variables were: gender; age (18 - 29, 30 - 39, 40 - 49, 50 - 59, 60 - 69, 70 - 79, and ≥ 80 years); educational level (without education/incomplete elementary school, complete elementary school/incomplete high school, complete high school/incomplete higher education, and complete higher education or higher level); skin color (white, black, and mulatto); Brazilian macroregions (north, northeast, southeast, south, and midwest); and home place (urban and rural).

The analyses were conducted using Stata statistical package, version 13.1 (StatCorp, College Station, TX, US). Absolute and relative frequencies of the exposure variables and prevalence of outcomes for the total sample and exposure variables were obtained. The comparison of asthma medical diagnosis prevalence according to the exposure variables was done through the χ²-test, in which results with p< 0.05 were considered statistically significant. Owing to the complexity of the sample outline, such variables were used based on the group of svy commands of the statistical software. The Research Ethics Committee approved the NHS under the number 328.159 from June 26, 2013. Participation of adults in the research was voluntary, and information confidentiality was ensured.

RESULTS

The final sample included 60,202 adults with more women, about two-thirds in the age range of 18-49 years, mostly white or mulatto, about 13% with complete higher education, and around 80% residents from the urban area (Table 1). The prevalence of asthma medical diagnosis in this population was 4.4% (95%CI 4.1 - 4.7), which was higher in females when compared with male subjects (p< 0.001) (Table 1). With regard to age, the prevalence was higher in those aged 18 - 29 years and lower in the age range ≥ 80 years, with variances in the other ages. There was not a difference in the prevalence according to educational level.

The white subjects showed more prevalence of medical diagnosis when compared with the others (p < 0.015). The urban area residents reported more medical diagnosis than those from rural areas (p< 0.001). The southern area presented the highest prevalence and the northeastern area, the lowest (p< 0.001) (Table 1).

As to the FUs in the country, Rio Grande do Sul showed the highest prevalence of asthma medical diagnosis, whereas the lowest ones were found in Alagoas, Maranhão, and Bahia (Figure 1).

Among the individuals who reported asthma medical diagnosis, around 43 and 30% of women and men, respectively, presented an asthma crisis in the last 12 months. About 80% of them took a medication for asthma, and 16.1% women and 15.0% men mentioned limitations of severe or very severe degree to perform their activities owing to the limitations from the disease (Figure 2).

DISCUSSION

Studies on asthma with a representative sample including Brazilian adults are rare; among them, the PNAD should be mentioned, which allowed assessing a time tendency among the years of 1998, 2003, and 2008. Asthma medical diagnosis in adults aged ≥ 20 years in the PNAD presented stability throughout the years of about 4.0%, similar to the result obtained in the current NHS⁷7. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostra de Domicílios: Um panorama da saúde no Brasil - acesso e utilização de serviço, condições de saúde e fatores de risco e proteção à saúde, 2008. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2010. Disponível em: Disponível em: http://bvsms.saude.gov.br/bvs/publicacoes/pnad_panorama_saude_brasil.pdf . (Acessado em 2 de junho de 2015).
http://bvsms.saude.gov.br/bvs/publicacoe... ⁹9. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostra de Domicílios: acesso e utilização de serviços, 2003. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística 2005..

The WHS assessed the adult population in 70 countries and found, in 2002-2003 period, a 4.3% global prevalence of asthma diagnosis self-report (95%CI 4.2 - 4.4) restricting the analysis for adults aged 18 - 45 years. The outcomes of this research, mainly for Brazil, pointed out a 12.4% prevalence (95%CI 12.9 - 22.6)⁵5. To T, Stanojevic S, Moores G, Gershon AS, Bateman ED, Cruz AA, et al. Global asthma prevalence in adults: findings from the cross-sectional world health survey. BMC Public Health 2012; 12: 204.. The higher age limit of 45 years, in this WHS analysis, was chosen with the objective of decreasing the possible false-positive results owing to chronic obstructive pulmonary disease (COPD) that assails the elderly subjects. Another WHS publication, which did not present restriction of higher age limit, showed a 6.0% global prevalence of asthma diagnosis self-report, which in Brazil was of 12.0% (95%CI 11.0 - 13.1)⁶6. Sembajwe G, Cifuentes M, Tak SW, Kriebel D, Gore R, Punnett L. National income, self-reported wheezing and asthma diagnosis from the World Health Survey. European Respir J. 2010; 35(2): 279-86.. Asthma prevalence with population older than 45 years of age might be overestimated, which was seen in the global prevalence of diagnosis self-report in the WHS; in Brazil, however, there was a minimum difference, including or not including the oldest subjects (12.4% in the entire sample and 12.0% considering the age range until 45 years)⁵5. To T, Stanojevic S, Moores G, Gershon AS, Bateman ED, Cruz AA, et al. Global asthma prevalence in adults: findings from the cross-sectional world health survey. BMC Public Health 2012; 12: 204.. There is a possibility that the main reason responsible for such high prevalence seen in Brazil, in the WHS, was how the outcome was evaluated, that is, "asthma diagnosis self-report," which could have overestimated the prevalence.

In the adult age, most investigations demonstrated a larger prevalence of asthma in the female gender, regardless of the definition used (symptoms or medical diagnosis)¹⁰10. Almqvist C, Worm M, Leynaert B; working group of GALENWPG. Impact of gender on asthma in childhood and adolescence: a GA2LEN review. Allergy 2008; 63(1): 47-57., differently of childhood, in which the male gender presents a wider prevalence. Although the reasons for these differences according to gender have not been established, possible explanations were proposed in literature, such as the smaller diameter of the airways to the pulmonary volume and higher sensitivity to allergens in male children¹⁰10. Almqvist C, Worm M, Leynaert B; working group of GALENWPG. Impact of gender on asthma in childhood and adolescence: a GA2LEN review. Allergy 2008; 63(1): 47-57..

Both the low educational and low socioeconomic levels have been considered as risk factors for asthma in Latin America, even though this investigation could not find this outcome. It is worth noting that it is hard to distinguish poverty from other environmental variables or lifestyles that go with it and may be involved in asthma, such as pollution, smoking, respiratory infections, low weight, and prematurity¹¹11. Benicio MH, Ferreira MU, Cardoso MR, Konno SC, Monteiro CA. Wheezing conditions in early childhood: prevalence and risk factors in the city of Sao Paulo, Brazil. Bull World Health Organ 2004; 82(7): 516-22. ¹²12. Cunha SS, Barreto ML, Rodrigues LC. The importance of research on the association between socioeconomic conditions and asthma. Rev Panam Salud Publica 2007; 22(6): 438-40. ¹³13. Mallol J. [Satellite symposium: Asthma in the World. Asthma among children in Latin America]. Allergol Immunopathol 2004; 32(3): 100-3.. An ecological analysis including 20 Brazilian centers presented a direct association between asthma prevalence and inappropriate sanitation conditions, child mortality, inequity index (GINI), and mortality of all causes¹⁴14. Franco R, Santos AC, Nascimento HF, Souza-Machado C, Ponte E, Souza-Machado A, et al. Cost-effectiveness analysis of a state funded programme for control of severe asthma. BMC Public Health 2007; 7: 82..

Some studies, not only in Brazil but also in other Latin American countries, Europe, Asia, and Africa, found higher asthma (self-reported or symptoms) prevalence in the urban area when compared with the rural area¹⁵15. Aberg N, Engström I, Lindberg U. Allergic diseases in Swedish school children. Acta Paediatr Scand 1989; 78(2): 246-52. ¹⁶16. Cooper PJ, Rodrigues LC, Cruz AA, Barreto ML. Asthma in Latin America: a public heath challenge and research opportunity. Allergy 2009; 64(1): 5-17. ¹⁷17. Nicolaou N, Siddique N, Custovic A. Allergic disease in urban and rural populations: increasing prevalence with increasing urbanization. Allergy 2005; 60(11): 1357-60. ¹⁸18. Nilsson L, Castor O, Lofman O, Magnusson A, Kjellman NI. Allergic disease in teenagers in relation to urban or rural residence at various stages of childhood. Allergy 1999; 54(7): 716-21. ¹⁹19. Solé D, Cassol VE, Silva AR, Teche SP, Rizzato TM, Bandim LC, et al. Prevalence of symptoms of asthma, rhinitis, and atopic eczema among adolescents living in urban and rural areas in different regions of Brazil. Allergol Immunopathol 2007; 35(6): 248-53. ²⁰20. Wehrmeister FC, Menezes AM, Cascaes AM, Martinez-Mesa J, Barros AJ. Time trend of asthma in children and adolescents in Brazil, 1998-2008. Rev Saude Publica 2012; 46(2): 242-50. ²¹21. Weinberg EG. Urbanization and childhood asthma: an African perspective. J Allergy Clinical Immunol 2000; 105(2 Pt 1): 224-31.. The few studies carried out in the rural area suggest that population living there are protected from asthma or allergy for unknown reasons²²22. Beran D, Zar HJ, Perrin C, Menezes AM, Burney P, for the Forum of International Respiratory Societies working group c. Burden of asthma and chronic obstructive pulmonary disease and access to essential medicines in low-income and middle-income countries. Lancet Respiratory Med 2015; 3(2): 159-70. ²³23. Cooper PJ, Chico ME, Rodrigues LC, Ordonez M, Strachan D, Griffin GE, et al. Reduced risk of atopy among school-age children infected with geohelminth parasites in a rural area of the tropics. J Allergy Clin Immunol 2003; 111(5): 995-1000. ²⁴24. Schei MA, Hessen JO, Smith KR, Bruce N, McCracken J, Lopez V. Childhood asthma and indoor woodsmoke from cooking in Guatemala. J Expo Anal Environ Epidemiol 2004; 14(Suppl 1): S110-7.. In the last year of PNAD follow-up (2008), there was a 4.1% prevalence in the urban area against the 3.3% in the rural area in adulthood⁷7. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostra de Domicílios: Um panorama da saúde no Brasil - acesso e utilização de serviço, condições de saúde e fatores de risco e proteção à saúde, 2008. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2010. Disponível em: Disponível em: http://bvsms.saude.gov.br/bvs/publicacoes/pnad_panorama_saude_brasil.pdf . (Acessado em 2 de junho de 2015).
http://bvsms.saude.gov.br/bvs/publicacoe... .

With regard to the macroregions of the country, in both the PNAD and the current research, the southern area showed a higher prevalence of asthma medical diagnosis, regardless of the age⁷7. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostra de Domicílios: Um panorama da saúde no Brasil - acesso e utilização de serviço, condições de saúde e fatores de risco e proteção à saúde, 2008. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2010. Disponível em: Disponível em: http://bvsms.saude.gov.br/bvs/publicacoes/pnad_panorama_saude_brasil.pdf . (Acessado em 2 de junho de 2015).
http://bvsms.saude.gov.br/bvs/publicacoe... ²⁰20. Wehrmeister FC, Menezes AM, Cascaes AM, Martinez-Mesa J, Barros AJ. Time trend of asthma in children and adolescents in Brazil, 1998-2008. Rev Saude Publica 2012; 46(2): 242-50.. Access to health services might be one of the factors responsible for more diagnosis in the South; another aspect as to the southern area is its climate, because several studies in literature mention the cold temperature as a "trigger" for asthma crisis²⁵25. Guo Y, Jiang F, Peng L, Zhang J, Geng F, Xu J, et al. The association between cold spells and pediatric outpatient visits for asthma in Shanghai, China. PloS One 2012; 7(7): e42232. ²⁶26. Zhang Y, Peng L, Kan H, Xu J, Chen R, Liu Y, et al. Effects of meteorological factors on daily hospital admissions for asthma in adults: a time-series analysis. PloS One 2014; 9(7): e102475.. Nevertheless, one of the difficulties in understanding the higher asthma prevalence in some regions of the country is because Brazil does not have a single genetic standard. There are several influences of million immigrants who colonized different areas in the country, which could also be responsible for not being able to find a higher asthma prevalence in the urban area, as it would be expected.

About 90% of the Brazilian participants, in the WHS, reported being under treatment for asthma, and around one-fourth used medication in the last 2 weeks, and 13.5% self-reported bad or very bad health²⁷27. Theme-Filha MM, Szwarcwald CL, Souza-Junior PR. Socio-demographic characteristics, treatment coverage, and self-rated health of individuals who reported six chronic diseases in Brazil, 2003. Cad Saude Publica 2005; 21(Suppl):43-53.. Despite the divergences between asthma prevalence in the WHS when compared with the NHS, we must emphasize that, in the 12-13-year period between the two surveys, results about medical treatment, medication use, and limitation to activities or self-report or health remain with similar prevalence. This indicates that asthma management is still not appropriate in our country; around 40% of women and 30% of men showed an asthma crisis last year, of which about 20% did not take medication. We could not find the reasons for the lack of treatment through the questionnaire used in this research. According to the Brazilian consensus of asthma²⁸28. Sociedade Brasileira de Penumologia e Tisiologia. Diretrizes da Sociedade Brasileira de Pneumologia e Tisiologia para o manejo da asma-2012. J Bras Pneumol 2012; 38(Supl 1): S1-S46., every asthmatic patient must be treated; those with occasional asthma must use medication when symptoms are present, and the remaining ones should use it permanently. Because it was found that a part of the population does not receive treatment, it was expected that such patients would report a great limitation to activities, as seen in this study, or would consider their health as moderate, bad, or very bad similar to that in the WHS (53.8%)²⁹29. Theme-Filha MM, Szwarcwald CL, Souza Junior PRB. Medidas de morbidade referida e inter-relações com dimensões de saúde. Rev Saude Publica 2008; 42(1): 73-81.. In addition, patients using medications showed around two times more limitation to their activities owing to asthma than those who were not using it (data were not presented in tables with p-value of 0.029 in the χ²-test), which might indicate a greater severity of the disease.

A study done by Franco et al., including severe asthmatics from the ProAR program in Salvador (Bahia state, Brazil), showed that a control program with free monitoring, examinations, care, and medication could decrease morbidity (less than 5 hospitalization days and less than 69 visits to the emergency room, in average, per year), improve asthma control scores in 50% and quality of life scores in 74%, and decrease the annual costs for health services in US$ 387 per patient and family costs in US$ 733¹⁴14. Franco R, Santos AC, Nascimento HF, Souza-Machado C, Ponte E, Souza-Machado A, et al. Cost-effectiveness analysis of a state funded programme for control of severe asthma. BMC Public Health 2007; 7: 82..

There is not an established pattern for the tendency of asthma prevalence in the world. Some countries have showed a decrease of asthma, whereas in others, there is a stability or increase of asthma prevalence or severity. When Solé et al.¹⁹19. Solé D, Cassol VE, Silva AR, Teche SP, Rizzato TM, Bandim LC, et al. Prevalence of symptoms of asthma, rhinitis, and atopic eczema among adolescents living in urban and rural areas in different regions of Brazil. Allergol Immunopathol 2007; 35(6): 248-53. assessed the phases I and III adolescents of ISAAC, in many Brazilian cities, they found a small, but significant, decrease of attacks and night cough symptoms, although this result was not consistent in the different studied cities. In the age range of the adults, it has been seen a stability of asthma medical diagnosis the last years, based on PNAD and NHS²⁹29. Theme-Filha MM, Szwarcwald CL, Souza Junior PRB. Medidas de morbidade referida e inter-relações com dimensões de saúde. Rev Saude Publica 2008; 42(1): 73-81..

The NHS results show that around one-fifth (18.7%; 95%CI 14.9 - 23.3) of the subjects with asthma medical diagnosis and crisis in the last year were not receiving treatment; in this same group of patients, 15.6% (95%CI 11.9 - 20.3) reported a severe or very severe limitation in their daily activities.

CONCLUSIONS

It is believed that several factors were responsible for the stability or decrease of asthma medical diagnosis in Brazilian adults. Among them, we can mention more access to health services in the country and availability of free medication for asthma in the last years, besides the introduction of the drug in the Programa Aqui tem Farmácia Popular ³⁰30. Costa KS, Francisco PMSB, Barros MBdA. Conhecimento e utilização do Programa Farmácia Popular do Brasil: estudo de base populacional no município de Campinas-SP. Epidemiol Serviços Saude 2014; 23(3): 397-408.. A recent publication about the "Attention Programs and Center to Asthmatics (PCAAs)" evaluated that there is still a lot to be done, despite the improvement in the disease treatment in Brazil, such as expanding the PCAAs to other centers in the country³¹31. Stelmach R, C-Neto A, Fonseca ACdCF, Ponte EV, Alves G, Araujo-Costa IN. Programas e centros de atenção a asmáticos no Brasil; uma oficina de trabalho: revisitando e explicitando conceitos. J Bras Pneumol 2015; 41(1): 3-15. and implementing a plan for an asthma care line.

References

Publication Dates

History