Exercise Induced Bronchospasm and associated factors in primary school children: a cross-sectional study

Abstract

Background: Exercise Induced Bronchospasm(EIB) is not equivalent to asthma. As many as 20%of school aged children are estimated to have EIB. In Nigeria, there is still a dearth of information on EIB as a clinical entity. This study determined the presence of EIB(using pre and post-exercise percentage difference in peak expiratory flow rate(PEFR) and associated factors such as age, gender, social class and nutritional status in primary school children in Nnewi, Anambra state, South-East Nigeria. The study also grouped those with EIB into those with asthma(EIB_A) and those without asthma(EIB_WA).

Methods: This was a community based cross-sectional study involving 6-12 year olds. The PEFR was taken at rest and after a 6 min free running test on the school play-ground using a Peak Flow Meter. A diagnosis of EIB was made if there was a decline of ≥ 10%. Those who had EIB were grouped further based on the degree of decline in post-exercise PEFR (a decline ≥ 10% < 25% → Mild EIB, ≥ 25% < 50% → Moderate EIB and ≥ 50% → Severe EIB) and then categorized as those with EIB_WA/EIB_A.

Results: EIB in the various minutes post-exercise was as follows: 19.2%(1^stmin), 20.9%(5^thmin), 18.7%(10^thmin), 10%(20^thmin), 0.7%(30^thmin). Mild EIB accounted for the greater proportion in all minutes post-exercise and none of the pupils had severe EIB. Using values obtained in the 5^thmin post-exercise for further analysis, EIB_WA/EIB_A = 84.1%/15.9% respectively. Mean difference in the post-exercise PEFR of EIB/no EIB and EIB_WA/EIB_A was -48.45(t = -7.69, p = < 0.001) and 44.46(t = 3.77, p = 0.01) respectively. Age and gender had a significant association to the presence of EIB and 58% of the pupils with EIB were of high social class. The BMI for age and gender z-scores of all study subjects as well as those with EIB was -0.34 ± 1.21, -0.09 ± 1.09 respectively. Other features of allergy(history of allergic rhinitis: OR-5.832, p = 0.001; physical findings suggestive of allergic dermatitis: OR-2.740, p = 0.003)were present in pupils diagnosed with EIB.

Conclusion: EIB has a high prevalence in primary school children in Nnewi and the greater proportion of those with EIB had EIB_WA. EIB therefore needs to be recognized as a clinical entity and stratified properly based on the presence or absence of asthma. This will help the proper management and prognostication.

Keywords: Childhood; Exercise induced bronchoconstriction; Nigeria.