SCREENING FOR CHILDHOOD ASTHMA USING AN EXERCISE TEST

Background Screening for asthma in children in the community could hav e advantages at a time when prevalence rates of the condition and asso ciated hospital admission rates are rising. Aim. The aim of this study was to assess the usefulness of a standard exercise test as a marker of asthma or potential asthma in children, and to examine the relation ship between asthma and other respiratory tract illnesses. Method. In 1985 a cross-sectional research study was undertaken in 10 primary sch ools in West Glamorgan; the children were followed up over six years u ntil 1991. The exercise test involved measuring peak expiratory flow r ate before and after the children ran as fast as they could for six mi nutes. A control group of children with a negative exercise test resul t were compared with those not known to have asthma who had a positive result (fall in peak expiratory flow rate of 15% or greater), using c linical data. Similar clinical comparisons were undertaken between the children known to have asthma and a control group. Results. Of 864 ch ildren not known to have asthma, 60 had a positive exercise result. Of 92 children known to have asthma, 33 had a positive test result and s even were unable to finish the test because of bronchospasm, a sensiti vity of 43% and a specificity of 93%. Follow up of 55 of the 60 childr en not known to have asthma but who had an abnormal response to the te st showed that 32 had developed clinically recognizable asthma six yea rs later. There was a significantly higher prevalence of atopic and re spiratory illnesses (otitis media, hay fever and eczema) in the group of children with bronchial hyperreactivity demonstrated on exercise th an in those without bronchial hyperreactivity. Conclusion. This resear ch shows that bronchial hyperreactivity demonstrated by an exercise te st can be a marker for childhood asthma. The study has also identified other respiratory tract illnesses which appear to belong to the same spectrum as asthma.