Background: Asthma is a common childhood illness, with a prevalence of 1 in 10 children. Exercise-induced bronchospasm (EIB) is a common feature of asthma and is found more often in children than in adults.
Objective: To determine the prevalence and potential impact of various factors on the prevalence of EIB in Thokoza schoolchildren.
Methods: Data were collected on respiratory health and the home environment of children living in Thokoza, Gauteng. A total of 475 9- and 10-year-old children performed the free-running asthma screening test (FRAST). An abnormal response to FRAST was defined as a reduction in the post-exercise peak flow of more than 15% of the pre-exercise value, at 3- and 10- minute intervals. All children who had a fall in post-exercise flow rate (PEFR) of more than 15% on 2 occasions after FRAST were classified as having EIB.
Results: Using the above criteria to diagnose EIB, an overall prevalence rate of 7.26% (95% confidence interval (CI): 4.5 - 10.3%) was recorded. A less rigorous definition of EIB is a fall in PEFR of more than 10% on 2 occasions after FRAST, and if this was used then the prevalence of EIB was 15.69% (95% CI: 10.6 - 20.8%). Difficulty breathing and a tight chest were the most prevalent respiratory symptoms in children with EIB (odds ratio (OR): 1.79, 95% CI: 0.49 - 6.49 and OR 1.69, 95% CI: 0.72 - 3.99, respectively). The use of gas and electricity as domestic fuels was the strongest risk factor associated with EIB, as shown by logistical regression analysis using an adjusted OR in a reduced model (OR 2.44, 95% CI: 0.71 - 8.44 and OR 2.33, 95% CI: 0.59 - 9.24, respectively).
Conclusion: The prevalence of EIB reported in this study is higher than that reported in studies from other African countries, with the exception of a study from Kenya. Findings of the present study suggest that there may be a trend towards increasing prevalence of EIB in South African urban areas.