The use of 4.5% hypertonic saline challenge test in diagnosing asthma in children with chronic recurrent cough

Background The 4.5% hypertonic saline (HS) challenge test has several benefits compared to histamine challenge test as gold stan- dard. Saline is an inexpensive non-pharmacological substance which is relatively safe. Its mechanism in inducing bronchospasm resembles that of asthma. Moreover, it can easily be made in a modest medical laboratory. Objective To determine the ability of 4.5% HS challenge test com- pared to histamine challenge test in diagnosing asthma in children with chronic recurrent cough (CRC). Methods This study was a diagnostic test on children with CRC aged 6 to 14 years, conducted in outpatient clinic of Department of Child Health, Cipto Mangunkusumo Hospital, Jakarta. All subjects underwent lung function tests. Subjects whose FEV 1 was <80% were diagnosed as asthmatic and underwent the 4.5% HS challenge test only. Those whose FEV 1 was 80% underwent the histamine chal- lenge test followed by the 4.5% HS challenge test one or two weeks later. Test results were expressed as positive or negative. Based on the results, we calculated the sensitivity, specificity, predictive val- ues, and likelihood ratios of the 4.5% HS challenge test. Results Forty-five subjects, consisting of 22 boys and 23 girls, were enrolled. The average age of subjects was 9 years old. Atopic history in the family or in subjects themselves was found in 80% of subjects. Eight subjects had FEV 1 of <80%. Forty-four subjects were diagnosed with asthma based on a baseline FEV 1 of