Low prevalence of asthma in sub Saharan Africa: A cross sectional community survey in a suburban Nigerian town

Abstract

Asthma remains an important cause of morbidity and mortality, especially in developing countries but the prevalence in Nigeria is not well described. Using the European Community Respiratory Health Survey (ECRHS) standard screening questionnaire and asthma criteria, we recruited a representative sample of adults resident in a suburban community in Nigeria through a stratified three-stage cluster sampling technique. Out of a total of 3590 individuals contacted, 2310 responded and provided completed data (62.8% female). The prevalence of respiratory symptoms ranged from 0.4% (95% CI: 0.1-0.6) to 9.1% (95% CI: 7.6-10.6). Apart from nasal allergies, the most frequently reported symptoms were 'woken up by an attack of breathlessness at any time in the last 12 months' (2.4%, 95% CI: 1.8-3.0) and 'woken up by an attack of cough at any time in the last 12 months' (2.9%, 95% CI: 2.0-3.7). The combined proportion of respondents reporting previous asthma attack or currently taking asthma medication within the preceding 12 months (diagnosed asthma) was 1.5%, 95% CI: 1.0-2.0. The proportion with 'probable asthma' based on ECRHS criteria of any three symptoms of asthma (woken up by an attack of breathlessness or previous asthma attack or currently taking asthma medication within the preceding 12 months) was 3.1%, 95% CI: 2.0-4.3 for men and 3.3%, 95% CI: 2.4-4.2 for women. The prevalence of asthma in this suburban Nigerian population is low. Determinants of adult asthma distribution in low-income setting need further clarification.