Weight gain with add‐on second‐generation antipsychotics in bipolar disorder: a naturalistic study

Objective Our aim was to investigate the prevalence and magnitude of weight gain in‐patients with bipolar disorder when treated with a second‐generation antipsychotic as an add‐on treatment to a mood stabilizer in routine clinical practice. Methods Data were derived from the quality register for bipolar disorder in Sweden (BipoläR). Patients with bipolar disorder who started add‐on treatment with a SGA ( n  = 575) were compared at next yearly follow‐up with age and sex matched patients who were only treated with a mood stabilizer ( n  = 566). The primary outcome measure was change in body weight and body mass index ( BMI ). We also assessed the prevalence of clinically significant weight gain defined as ≥7% gain in body weight. Results The group that received add‐on treatment with antipsychotics neither gained more weight nor were at higher risk for a clinically significant weight gain than the reference group. Instead, factors associated with clinically significant weight gain were female sex, young age, low‐baseline BMI , and occurrence of manic/hypomanic episodes. Conclusion We found no evidence of an overall increased risk of weight gain for patients with bipolar disorder after receiving add‐on SGA to a mood stabilizer in a routine clinical setting.