Date created: | Last Updated:

Category: Uncategorized

Description: It is a widely held belief that patients with schizophrenia vary considerably in their response to antipsychotics in randomized controlled trials. In this project, we assumed that the overall variation due to individual treatment response (present in the treatment group) can be separated from random variation (present in the treatment and control group) by comparing the variability between groups. Thus, a personal element of response should be reflected by a clinically relevant increase in overall variability in the treatment compared to the control group. We included double-blind, placebo-controlled, randomized trials investigating adults with a diagnosis of schizophrenia spectrum disorders and licensed antipsychotics. We extracted the mean and standard deviation of the Positive and Negative Syndrome Scale pre-post difference scores. The outcome measure was the overall variability ratio (VR) of treatment vs. control in a meta-analysis across studies. We hypothesized that a personal element of response would be reflected by a significant overall increase in variability of treatment compared to control. After illustrating the different components of variation in RCTs with simulated data, we assessed the variability ratio in 52 studies and 15,360 patients. The variability was slightly lower in treatment compared to control (VR = 0.97, 95% CI: 0.95, 0.99, P = 0.01). Within the current literature using RCTs with a majority being parallel placebo-treatment trials, we found no evidence that antipsychotic treatment increased the outcome variance compared to control, suggesting no personal element of response. Instead, the outcome variance was slightly lower in the treatment compared to the control group. Although this cannot rule out that subsets of patients responded differently to treatment, the overall small difference in variances suggests that the average treatment effect is a reasonable assumption for the individual patient.