Purpose: Asthma is an important cause of morbidity and mortality worldwide and information on the prevalence of asthma in Nigeria is inconsistent. Nationally representative data, important for health planning is unavailable. We aimed to determine the current prevalence of asthma and allergic rhinitis in Nigeria.
Materials and methods: A cross-sectional population survey conducted between June 2017 and March 2018 across five cities representing five geo-political zones in Nigeria. Validated screening questionnaires were used to identify persons with asthma and allergic rhinitis respectively. Asthma was defined as physician diagnosed asthma, clinical asthma and by presence of wheeze in the last 12 months respectively. Socio-demographic information, tobacco smoking, sources of household cooking fuel were also obtained.
Results: A total of 20063 participants from 6024 households were screened. The prevalence (95% confidence interval) of physician diagnosed asthma, clinical asthma and wheeze was 2.5% (2.3-2.7%), 6.4% (6.0-6.64%) and 9.0% (8.6-9.4%) respectively. The prevalence of allergic rhinitis was 22.8% (22.2-23.4%). The prevalence of asthma and rhinitis increased with age (prevalence of clinical asthma: 3.1% (2.8-3.4%), 9.8% (9.1-10.5) and 10.7% (9.4%-12.0) among 6-17 years, 18-45 years and >45 years respectively). Prevalence also varied across different cities with the highest prevalence of clinical asthma occurring in Lagos (8.0%) and the lowest in Ilorin (1.1%). The frequency of allergic rhinitis among persons with clinical asthma was 74.7%. Presence of allergic rhinitis, family history of asthma, current smoking and being overweight were independent determinants of current asthma among adults.
Conclusion: The prevalence of asthma and allergic rhinitis in Nigeria is high with variabilities across regions and age groups. The number of persons with clinical asthma in Nigeria (approximately 13 million) is likely to rank among the highest in Africa. This warrants prioritization by stakeholders and policy makers to actively implement risk reduction measures and increase investment in capacity building for the diagnosis and treatment of asthma and allergic rhinitis.