EXERCISE-INDUCED BRONCHOSPASM IN GHANA - DIFFERENCES IN PREVALENCE BETWEEN URBAN AND RURAL SCHOOLCHILDREN

Background - As more developing countries adopt a westernised style of living, an increase in the prevalence of asthma can be expected to oc cur in these areas. A study was undertaken to establish the normal res ponse to exercise in Ghanaian children and to use these normal values to determine the prevalence of exercise induced bronchospasm (EIB) in urban rich (UR), urban poor (UP), and rural (R) school children. Skin test reactivity to common inhalant allergens in UR, UP, and R children with and without EIB was also investigated. Methods - Two hundred chi ldren aged 9-16 years without a previous history of respiratory sympto ms were randomly selected and underwent free running exercise testing. A normal response to exercise was defined as the group mean change ex piratory flow rate (PEFR) +/- standard deviations. This value was used to identify the prevalence of EIB in UR, UP, and R schoolchildren. A total of 1095 children from three different schools underwent exercise testing (220 UP, 599 UR, 276 R), after which 916 children underwent s kin prick testing to six common inhalant allergens (D farinae, D ptero nyssinus, cat, dog, Aspergillus flavus and Candida albicans). Results - From the results of exercise testing in asymptomatic children the no rmal range was defined as a fall in PEFR of <12.5% after exercise. Thi rty four children were classified as having EIB on the basis of the ab ove definition, giving an overall prevalence of 3.1%. The prevalence o f EIB was significantly higher in UR children (4.7%) than in both UP ( 2.2%; p<0.05) and R children (1.4%; p<0.01). However, the prevalence r ates in the UP and R children were similar. The prevalence of atopy in the whole population was 4.4%. Of the children with EIB, 10% were ski n test positive to at least one of the allergens tested. The prevalenc e of atopy was significantly higher in UR children (6.55%, 95% confide nce interval (CI) 4.5% to 9.2%) than in UP (2.9%, 95% CI 0.9% to 6.7%) and R children (1.5%, 95% CI 0.4% to 3.7%), respectively (p<0.005). C onclusions - The prevalence of EIB and atopy is higher in urban rich t han in urban poor or rural children suggesting that, in addition to ge netic predisposition, social and environmental factors such as wealth, life style, and housing are important determinants of these phenotype s.