Effects of patient demographics,risperidone dosage,and clinical outcome on body weight in acutely exacerbated schizophrenia

BACKGROUND: Predictors for risperidone-related weight gain remain unclear. This study aimed to identify clinical factors influencing body weight in risperidone-treated patients. METHOD: One hundred forty-six newly hospitalized DSM-IV schizophrenia patients with acute exacerbation entered this prospective, 6-week, repeated-measures trial. The mean +/- SD risperidone dose was 4.3 +/- 1.4 mg/day at week 6. Efficacy, body weight, and tolerability were measured biweekly. Efficacy was assessed with the Positive and Negative Syndrome Scale (PANSS) and the Nurses' Observation Scale for Inpatient Evaluation (NOSIE). For determining the impacts of possible prognostic factors on body weight, we utilized generalized estimating equation methods to control for other variables and the within-subject dependence over repeated assessments. RESULTS: After the effects of other factors (including baseline body weight) were adjusted, every 1-week increase in treatment duration raised body weight by 0.442 kg (p <.0001). Increasing baseline body weight by 1 kg reduced weight gain by 0.022 kg (p <.0001). Every 1-year increment in age decreased body weight by 0.052 kg (p <.001). Undifferentiated subtype predicted higher weight by around 0.9 kg than other sub-types (p <.05). Each 1-mg/day increment in risperidone dosage heightened body weight by 0.084 kg (p =.015). Responders (those with PANSS total-score reduction > or = 20%) also had higher weight by 0.513 kg on average (p =.007). Specifically, every 1-point diminution in score in PANSS total, PANSS positive, PANSS negative, PANSS cognitive, and NOSIE increased body weight, on average, by 0.029 kg, 0.057 kg, 0.079 kg, 0.079 kg, and 0.035 kg, respectively (p < or =.009). Other variables did not have significant influences. CONCLUSION: The results suggest that lower initial body weight, younger age, undifferentiated subtype, higher dosage, and treatment response (for positive, negative, and cognitive symptoms and social functioning) are associated with greater weight gain in acutely ill patients treated with risperidone. Further studies with longer observation and in other populations are needed.