A further disadvantage was that although the entry criteria of the primary studies were generally similar, there were some differences in the baseline characteristics of the populations of the studies. Analysis showed a significant heterogeneity between the two studies used in the meta-analysis of those given continuous montelukast (p = 0.04, I 2 statistic = 77%). The study performed by Bisgaard et al.  included patients with quite mild symptoms of asthma, compared to those included in the study by Valovirta et al. . In the latter study, the patients had moderate-severe asthma (intermittent symptoms as well as one course of OCS or hospitalisation in the previous year) . There was another study which analysed relatively mild asthma .