The potential role of appetite in predicting weight changes during treatment with olanzapine.

Background: Clinically significant weight gain has been reported during treatment with atypical antipsychotics. It has been suggested that weight changes in patients treated with olanzapine may be associated with increased appetite.
Methods: Data were used from adult patients for whom both appetite and weight data were available from 4 prospective, 12- to 24-week clinical trials. Patients' appetites were assessed with Eating Behavior Assessment (EBA, Study 1), Platypus Appetite Rating Scale (PARS, Study 2), Eating Inventory (EI, Study 3), Food Craving Inventory (FCI, Study 3), and Eating Attitude Scale (EAS, Study 4).
Results: In Studies 1 (EBA) and 4 (EAS), patients who reported overall score increases on appetite scales, indicating an increase in appetite, experienced the greatest overall weight gains. However, in Studies 2 (PARS) and 3 (EI, FCI), patients who reported overall score increases on appetite scales did not experience greater weight changes than patients not reporting score increases. Early weight changes (2-4 weeks) were more positively correlated with overall weight changes than early or overall score changes on any utilized appetite assessment scale. No additional information was gained by adding early appetite change to early weight change in correlation to overall weight change.
Conclusions: Early weight changes may be a more useful predictor for long-term weight changes than early score changes on appetite assessment scales.
Clinical Trials Registration: This report represents secondary analyses of 4 clinical studies. Studies 1, 2, and 3 were registered at http://clinicaltrials.gov/ct2/home, under NCT00190749, NCT00303602, and NCT00401973, respectively. Study 4 predates the registration requirements for observational studies that are not classified as category 1 observational studies.