Objectives: This study examined whether participation in a weight control program (WCP) by patients with schizophrenia treated with olanzapine was also associated with improvements in clinical and functional outcomes.
Methods: A post-hoc analysis was conducted using data from the Chinese subgroup (n=330) of a multi-country, 6-month, prospective, observational study of outpatients with schizophrenia who initiated or switched to oral olanzapine. At study entry and monthly visits, participants were assessed with the Clinical Global Impression of Severity, and measures of patient insight, social activities, and work impairment. The primary comparison was between the 153 patients who participated in a WCP at study entry (n=93) or during the study (n=60) and the 177 patients who did not participate in a weight control program (non-WCP). Mixed Models for Repeated Measures with baseline covariates were used to compare outcomes over time. Kaplan-Meier survival analysis was used to assess time to response.
Results: Participants had a mean age of 29.0 years and 29.3 years, and 51.0% and 57.6% were female for WCP and non-WCP groups, respectively. Average initiated daily dose for olanzapine was 9.5±5.4 mg. WCP participants gained less weight than non-participants (3.9 kg vs 4.9 kg, P=0.03) and showed statistically significant better clinical and functional outcomes: greater improvement in illness severity (-2.8 vs -2.1, P<0.001), higher treatment response rates (94.1% vs 80.9%, P<0.001), shorter time to response (P<0.001), and greater improvement in patients' insight (P<0.001). Patients who enrolled in a WCP during the study had greater initial weight gain than those who enrolled at baseline (P<0.05), but similar total weight gain.
Conclusion: Participation in a WCP may not only lower the risk of clinically significant weight gain in olanzapine-treated patients, but may also be associated with additional clinical and functional benefits.
Keywords: body weight; epidemiologic studies; olanzapine; prospective studies; schizophrenia.