Fifty children (27 females, 23 males) ages 6–15 years who were referred for evaluation of suspected asthma had baseline FEV1 and FEF25‐75 of ⩾ 80% and FEF50 ⩾ 70% of predicted values. All had these tests repeated on the same day, after inhaling salbutamol. On a subsequent day PC‐20 (methacholine) was determined as an index of bronchial hyperreactivity (BH). Fourteen age‐matched healthy children (6 females, 8 males) were studied in a similar manner. There was no significant relationship between the PC20 and the change in FEF25‐75 or FEF50 following salbutamol. There was a negative correlation between the initial FEV1 (% predicted) and the percent change in FEV1 following salbutamol (P < 0.01). An increase in FEV1 of >6% occurred in 7/12 (58.3%) patients with PC20 ⩽ 0.25 mg/mL (Group I); in 7/24 (29.2%) patients with PC20 = 0.26–2.0 mg/mL (Group II); in only 1/14 (7.1%) patients with PC20 > 2.1 mg/mL (Group III) and in none of those asymptomatic (control) children with PC20 > 8.0 mg/mL (Group IV). All subjects who had a change in FEV1 > 6% after salbutamol had a PC20 < 8 mg/mL and this test detected the majority of patients with severe BH. However, although the sensitivity of the test was 100%, the predictive value was only 36%. We conclude that in the presence of a normal baseline FEV1 a change of > 6% following salbutamol inhalation is indicative of bronchial hyperreactivity. Pediatr Pulmonol 1991; 10:244–248.
- PC metacholine
- predictive value
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Pulmonary and Respiratory Medicine