Weight change after an atypical antipsychotic switch.
BACKGROUND
Atypical antipsychotics successfully treat schizophrenia and other conditions, with a lower incidence of extrapyramidal side effects than other agents used in treatment of these disorders. However, some atypical antipsychotics are associated with weight gain.


OBJECTIVE
To quantify the impact on weight and identify atypical antipsychotics causing the least amount of weight gain among patients switched from risperidone to olanzapine and olanzapine to risperidone.


METHODS
Patients included in the study (n = 86) were > or =18 years and had received > or =2 prescriptions for risperidone or olanzapine for > or =60 days, switched to the other atypical antipsychotic, and were dispensed > or =2 prescriptions for at least 60 days after the index date. Age, weight, and body mass index (BMI) were retrospectively abstracted from automated databases containing patient-specific prescription and vital sign information.


RESULTS
At the time of their switch, the average patient age was 53.2 years (range 25-83). The average weight change in patients switched to olanzapine (n = 47) was +2.3 kg (p = 0.01) and the BMI change was +0.8 kg/m(2) (p = 0.02). The average percent body weight change was +2.8% and the BMI change was +3.0%. The average weight change after patients switched to risperidone (n = 39) was -0.45 kg (p = 0.69) and BMI change was -0.2 kg/m2 (p = 0.64). The average percentage weight change was -0.4% and BMI change was -0.5%.


CONCLUSIONS
Practitioners' concern regarding weight changes after switching atypical antipsychotics seems warranted and patients should be provided consistent, ongoing weight monitoring. Further investigations should examine whether weight changes associated with atypical antipsychotic treatment further jeopardize this already at-risk population for severe comorbid conditions such as hypertension, coronary artery disease, and type 2 diabetes.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000493:pharmacokinetics; D001569:Benzodiazepines / Q000009:adverse effects; D015992:Body Mass Index; D001835:Body Weight / Q000187:drug effects*; D006801:Humans; D008875:Middle Aged; D009765:Obesity / Q000139:chemically induced* / Q000150:complications; D000077152:Olanzapine; D010865:Pilot Projects; D012189:Retrospective Studies; D018967:Risperidone / Q000009:adverse effects; D012559:Schizophrenia / Q000150:complications / Q000188:drug therapy
D014150:Antipsychotic Agents; D001569:Benzodiazepines; D018967:Risperidone; D000077152:Olanzapine