Thirteen studies (n=120) were included in the review: 2 RCTs (n=70), 3 open trials (n=37) and 8 case studies (n=13).
The results were based on the 86 patients receiving the intervention. The control groups were not included in the discussion of the results.
Results on the efficacy of CLZ and RIS combined therapy were mixed. Overall, RIS augmentation of CIS was effective in 43% of patients, as measured by the improvement in psychopathology. One RCT found CLZ and RIS combination therapy to be more effective than placebo; the other RCT had negative findings. Two open trials reported a reduction of 20% or more on measures of psychopathology (5 to 10 points; no p-values reported). A reduction in psychopathology of 20% or more was observed in 25% of patients treated with CLZ and RIS in the RCTs and in 45.9% of patients in the open trials. CLZ and RIS combined therapy was effective in 84.6% of patients in the case studies.
Several side-effects of RIS augmentation of CLZ were reported: the most frequently reported were extrapyramidal symptoms or akathisia (9.3% of patients), sedation (7% of patients) and hypersalivation (5.8% of patients). One RCT found a significant reduction in extrapyramidal side-effects with RIS augmentation compared with CLZ combined with placebo (no p value reported). The other RCT generally found no significant differences between the RIS and placebo groups on measures of side-effects, apart from an increase in sedation in the RIS group (no p-values reported).