Prevalence and factors associated with asthma among adolescents and adults in Uganda: a general population based survey

BACKGROUND: Recent large-scale population data on the prevalence of asthma and its risk factors are lacking in Uganda. This survey was conducted to address this data gap. METHODS: A general population based survey was conducted among people ≥12 years. A questionnaire was used to collect participants socio-demographics, respiratory symptoms, medical history, and known asthma risk factors. Participants who reported wheeze in the past 12 months, a physician diagnosis of asthma or current use of asthma medications were classified as having asthma. Asthmatics who were ≥ 35 years underwent spirometry to determine how many had fixed airflow obstruction (i.e. post bronchodilator forced expiratory volume in one second/forced vital capacity (FEV1/FVC) ratio < lower limit of normal (LLN). Descriptive statistics were used to summarize participants' characteristics. Prevalence of asthma was calculated as a proportion of asthmatics over total survey population. To obtain factors independently associated with asthma, a random-effects model was fitted to the data. RESULTS: Of the 3416 participants surveyed, 61.2% (2088) were female, median age was 30 years (IQR, 20-45) and 323 were found to have asthma. Sixteen people with asthma ≥35 years had fixed airflow obstruction. The prevalence of asthma was 11.0% (95% CI:8.9-13.2; males 10.3%, females 11.4%, urban 13.0% and rural 8.9%. Significantly more people with asthma smoked than non-asthmatics: 14.2% vs. 6.3%, p < 0.001, were exposed to biomass smoke: 28.0% vs. 20.0%, p < 0.001, had family history of asthma: 26.9% vs. 9.4%, p, < 0.001, had history of TB: 3.1% vs. 1.30%, p = 0.01, and had hypertension: 17.9% vs. 12.0%, p = 0. 003. In multivariate analysis smoking, (adjusted odds ratio (AOR), 3.26 (1.96-5.41, p < 0.001) family history of asthma, AOR 2.90 (98-4.22 p- < 0.001), nasal congestion, AOR 3.56 (2.51-5.06, p < 0.001), biomass smoke exposure, AOR 2.04 (1.29-3.21, p = 0.002) and urban residence, AOR 2.01(1.23-3.27, p = 0.005) were independently associated with asthma. CONCLUSION: Asthma is common in Uganda and is associated with smoking, biomass smoke exposure, urbanization, and allergic diseases. Health care systems should be strengthened to provide asthma care. Measures to reduce exposure to the identified associated factors are needed