Exercise-induced bronchospasm in Ilesa, Nigeria: A Comparative study of rural and urban school children

Abstract

Background: Exercise-induced bronchospasm (EIB) described as transient airway narrowing shortly after or during exercise is an important tool in epidemiological study of childhood asthma which has been increasing in prevalence globally. This study sets out to determine the prevalence of EIB in poor rural and affluent urban school children in Ilesa, South West Nigeria. Methods: School children in four secondary schools (two rural and two urban) in Ilesa were selected using multistage sampling. Their sociodemographic characteristics and history of wheeze/asthma were noted. The children had their forced expiratory volume in 1 s (FEV1) measured before, 5, 10 and 15 min after 6 min of free running exercise to achieve 80% of their maximal pulse rate. EIB was calculated as the change in FEV1pre- and post-exercise expressed as a percentage of the pre-exercise value ≥10%. The prevalence of EIB among the children as well as factors associated with it were determined. Results: A total of 230 children (129 rural and 101 urban) aged 9–17 years participated in the study over a 9 month period. Mean (standard deviation [SD]) age was 12.6 (1.9) years and Male:Female 1:1.1. Past history of wheeze in the children was obtained from 14 (13.9%) versus 2 (1.6%) of the urban and rural children, respectively. The mean (SD) FEV1% for the urban and rural children was 85.5 (18.5)% versus 78.5 (15.5)%, respectively. The prevalence of EIB was significantly higher among the urban children at 23.8%, 19.8% and 14.9% versus 8.5%, 5.4% and 3.1% for 5, 10 and 15 min post-exercise, respectively. History of wheezing in the past 12 months was the only factor significantly associated with EIB among the urban children. Conclusion: The prevalence of EIB is significantly higher among urban school children observed in about one in every five children. We recommend exercise testing as part of routine pre-entry school evaluation to Nigerian children in urban centers.