The number of wheezing episodes was described in three studies [2, 13, 18]. The final study  reported the number of wheezing episodes whereby a child was seen by a healthcare professional. Trials showed no effects of montelukast in preventing episodes of wheeze. The pooled estimate showed no statistically significant difference (MD = 0.07, 95% CI −0.14 to 0.29, mean for montelukast 2.68 vs placebo 2.54 (p = 0.5)). The figure shows no heterogeneity between the studies (Fig. 3a, p = 0.79, I 2 statistic = 0%).Fig. 3Intermittent montelukast vs placebo. a Numbers of wheezing episodes. b Unscheduled medical attendances. c Number of oral corticosteroid courses