Asthma prevalence and severity in low-resource communities.
OBJECTIVE
The prevalence of asthma was thought to be low in most low-income countries, but several reports have indicated this is not always true. This is a narrative review of recent publications on the burden of asthma in low and middle-income countries (LMIC) and underprivileged communities from developed countries.


RESULTS
Several studies have reported a low prevalence of asthma is LMIC, but indicate it is increasing. In the last few years, however, many surveys demonstrated this may not always be true. An analysis of the International Study for Asthma and Allergy in Childhood phase III database indicated although the prevalence of asthma among children and adolescents is higher in the developed countries, symptoms of asthma are often more severe in less affluent nations. The rate of uncontrolled asthma is also higher among underprivileged communities of developed countries. Secondary analysis of data generated by the WHO's world health survey performed among adults of 70 countries indicate symptoms of asthma are less frequent in middle-income countries and more frequent in the extremes, low income and high income. This sort of U shaped distribution suggests the disease (or syndrome) comprise more than one major phenotype related to diverse underlying mechanisms. In fact, recent reports show symptoms of asthma among the poor are associated with unhygienic living conditions, which may reduce the risk of atopy but increase the risk of nonatopic wheezing. Urbanization and exposure to air pollution also seem to contribute to an increasing prevalence severity of asthma in LMIC. Access to proper diagnosis and treatment with controller medications for asthma, specially with inhaled corticosteroids is feasible and cost-effective, reduce symptoms, health resource utilization, improves quality of life, and reduce mortality in low-resource settings.


CONCLUSIONS
Prevalence of asthma was thought to be low in low-income countries, but several reports have indicated this is not always true. Under diagnosis, under treatment, exposure to air pollution, and unhygienic living conditions may contribute to a higher frequency and severity of symptoms of asthma among the poor. Proper diagnosis and treatment with controller medications for asthma is feasible and cost-effective in low-resource settings.
aProAR-Núcleo de Excelência em Asma da Universidade Federal da Bahia, Salvador, Bahia bPulmonary Division, Heart Institute (InCor), Faculdade de Medicina da Universidade de São Paulo, São Paulo cFaculdade de Medicina de Jundiaí, Jundiaí, Brazil.
Álvaro A
ÁA
Cruz
Rafael
R
Stelmach
Eduardo V
EV
Ponte
D000397:Air Pollution / Q000009:adverse effects; D001249:Asthma / Q000453:epidemiology*; D016208:Databases, Factual; D003906:Developing Countries; D014943:Global Health; D006297:Health Services Accessibility; D006801:Humans; D011203:Poverty; D015995:Prevalence; D011788:Quality of Life; D012306:Risk; D012959:Socioeconomic Factors; D014481:United States; D014488:United States Health Resources and Services Administration; D014507:Urbanization