Hedges’ g was chosen as the treatment ES statistic for treatment efficacy since it controls for different sample sizes across studies, and was calculated in Comprehensive Meta-Analysis (CMA)Version 2.[66] Effect sizes were calculated using change scores because this increases the precision of ES estimators by controlling for pretreatment group differences of obsessive-compulsive symptom severity. Pre-and-post treatment means and standard deviations were entered into CMA, and were divided by the pooled post-treatment standard deviation. Effect sizes were standardized so that a positive result indicated that the active treatment (CBT or SRI) performed better than comparison conditions. For treatment response and symptom/diagnostic remission, the RR was selected to serve as the ES. The RR is the ratio of patients exhibiting response or remission in the active treatment condition divided by the probability of patients exhibiting response or remission in the comparison condition.[67] A RR of 1 suggests that response or remission outcomes did not differ between the two treatment conditions, whereas a RR of 4 indicates that the active treatment condition had a fourfold greater probability than the comparison condition of exhibiting
