Background: Metabolic side effects have been increasingly noted during therapy with novel antipsychotics, but there is a dearth of comprehensive comparative data in this area. The goal of this retrospective study was to examine the changes in weight parameters, fasting glucose, and fasting lipids in long-term inpatients treated with either risperidone or olanzapine.
Method: A retrospective study was performed by reviewing charts of patients at Oregon State Hospital, Salem, who were treated during July and August 1999, comparing metabolic outcomes during the first year of therapy with either risperidone or olanzapine. Data were analyzed also by age, sex, and concurrent use of lithium or valproate. Included for analysis were patients at least 18 years old with baseline weights obtained within 3 weeks of drug initiation, and baseline fasting triglycerides, cholesterol, and glucose obtained within 3 months prior to drug initiation and at 1 year of treatment (+/- 4 weeks). The patients meeting these criteria in each drug cohort (risperidone, N = 47; olanzapine, N = 47) included 1 patient with diagnosed diabetes mellitus prior to onset of treatment.
Results: Among those patients under 60 years old, olanzapine patients (N = 37) experienced significantly greater increases at 1 year in all metabolic parameters than the risperidone group (N = 39), except for weight variables: triglycerides +104.8 mg/dL (olanzapine) versus +31.7 mg/dL (risperidone) (p = .037); cholesterol +30.7 mg/dL (olanzapine) versus +7.2 mg/dL (risperidone) (p = .004); glucose +10.8 mg/dL (olanzapine) versus +0.74 mg/dL (risperidone) (p = .030). Patients under 60 years of age with concurrent use of lithium or valproate were associated with greater weight gain in both drug groups, but this difference was statistically significant only for the olanzapine cohort. Neither weight change nor use of lithium or valproate was associated with increases in glucose or lipids among those under 60 years old for either drug.
Conclusion: Olanzapine therapy is associated with significantly greater increases in fasting glucose and lipid levels for nongeriatric adult patients than risperidone, and the increases are not correlated with changes in weight parameters. Appropriate monitoring of fasting glucose and serum lipid levels should be considered during extended treatment with atypical antipsychotics.