Pooled subgroup analysis. Effects of corticosteroid treatment on the success rate inferred from all included studies and separately for the groups of studies on ICU patients and on non-ICU patients. Gray squares represent odds ratios (ORs) in individual trials with the size proportional to the weight of the study. The 95% confidence intervals (CIs) for individual trials are denoted by lines. The pooled subgroup estimate of the effect is represented by the blue diamond (with a width proportional to the confidence interval), and the combined overall effect is represented by the red diamond. The I2 test for heterogeneity was moderate overall (I2 = 36%), high in the analysis involving critically ill patients (I2 = 77.4%), and low in studies including non-ICU patients (I2 = 17.4%). The z test for interaction between subgroups was 0.36 (p = 0.72). The meta-analysis is performed by a random effects model.