Asthma Symptoms, Severity, and Control in Young Adolescents in Sub-Saharan Africa: A Multi-National Observational School-Based Study

Abstract

BackgroundThe increasing prevalence of asthma in urban areas of sub-Saharan Africa (sSA) will result in more children and adolescents suffering from severe asthma symptoms. To date, parents of symptomatic children in sSA face significant barriers in obtaining a diagnosis of asthma from a doctor. To inform community-based interventions to improve asthma control in sSA we sought, in this study, to generate data on the burden of asthma symptoms, symptom severity and asthma control in school-age adolescents, including those without a doctor-diagnosis of asthma.  MethodsThis study reports stages 1 and 2 (the observational component) of a 4-stage multi-country school-based study. In stage 1, young adolescents (12 to 14 years of age) attending primary and secondary schools in Blantyre (Malawi), Durban (South Africa), Harare (Zimbabwe), Kampala (Uganda), Kumasi (Ghana), and Lagos (Nigeria) were screened for asthma symptoms and doctor-diagnosis of asthma, using International Study of Asthma and Allergies in Children (ISAAC) questions. Then, after opt-in consent, symptomatic adolescents completed stage 2 which assessed asthma severity, treatment, and exposure to potential environmental risk factors. Also assessed in stage 2 were the European Respiratory Society (ERS)’s diagnostic criteria for asthma. Objective evidence of asthma was classified as a forced expiratory volume in 1 sec (FEV1) < 80% predicted/< lower limit of normal or forced expiratory volume in 1 sec/forced vital capacity (FEV1/FVC) <80% lower limit of normal, or an increase in absolute forced expiratory volume in 1 sec of ≥12% and/or >200 mL after a bronchodilator, or fraction of exhaled nitric oxide ≥25 ppb, or any combination. The study was registered with ClinicalTrials.gov (NCT03990402). FindingsThe stage 1 asthma screening questionnaire was completed by 27,272 adolescents from 149 schools in six sSA countries. Of these, 3,577 (13.1%) reported either wheeze or doctor-diagnosed asthma in the last 12 months or both (range; 4.2% in Malawi to 23.8% in South Africa). Over two thirds with asthma symptoms in stage 1 reported severe symptoms, and the majority of these had no diagnosis of asthma by a doctor. The stage 2 questionnaire was completed by 1,654 symptomatic adolescents, and in 1,546 one or more diagnostic markers were assessed. Objective evidence of asthma was found in 48.8% of the 813 undiagnosed adolescents with severe symptoms, and 42.4% undiagnosed with mild to moderate symptoms. 294 adolescents with a doctor-diagnosis of asthma in stage 2 had severe asthma symptoms, and 94 (31%) were not using asthma medications. In general, findings in stages 1 and 2 were consistent across the six sub-Saharan African countries. InterpretationA large proportion of adolescents in sSA with symptoms of severe asthma do not have a doctor diagnosis of asthma and are therefore not receiving appropriate asthma therapy. One solution to poor asthma control in sSA is to educate, diagnose, and treat asthma at schools. FundingNIHR (UK), MRC (UK).

Keywords: asthma, adolescents, sub Saharan Africa, asthma control