Prediction of long-term metabolic effects of olanzapine and risperidone treatment from baseline body mass index in schizophrenia and bipolar disorder

Baseline body mass index (BMI), baseline BMI status (normal, overweight, obese) and early (1 month) BMI increases were tested as predictors of 6- and 12- month increases in glucose and lipid measures in 82 olanzapine (OLZ)- and 78 risperidone (RIS)-treated patients with schizophrenia, schizoaffective disorder, or bipolar disorder who participated in a 12-month randomized, prospective metabolic effects study. Baseline BMI predicted greater fasting glucose and HgbA1c levels at 12 months for both treatments. Early BMI change predicted fasting glucose levels at 6 months, but not HgbA1c or BMI, at either time point. For patients who received no concomitant mood stabilizers, early BMI change predicted 12 month HgbA1c values in the OLZ group, and 6- (but not 12-) month fasting glucose and HgbA1c values in the RIS group. Neither baseline BMI nor early BMI change consistently predicted increases in lipids with either drug. OLZ-treated patients with normal baseline BMI had greater increases in total cholesterol, triglycerides, and non-HDL-cholesterol than those who were overweight or obese. In conclusion, higher baseline BMI predicted adverse glycemic changes after 12 months with OLZ and RIS. Individuals with normal baseline BMI may be most susceptible to OLZ-induced hyperlipidosis. Frequency of metabolic screening should be independent of baseline BMI or rapid increases in BMI.