Objective: Studies of behavioral weight loss intervention in patients with psychotic disorders are sparse, and its efficacy compared to other obese patients is unknown. Therefore, we compared the effect of a cognitive-behavioral weight loss intervention in obese subjects with psychotic disorders, other psychiatric diagnoses, and without psychiatric disorders.
Methods: A 12-month naturalistic study of weekly group or individual cognitive-behavioral weight management in 222 consecutively enrolled obese patients (body mass index [BMI], 43.7 ± 9.6 kg/m2) with psychotic spectrum disorders (PSDs, n = 47), other psychiatric disorders (OPDs, n = 49), and no psychiatric disorder (NPD, n = 126).
Results: Patients with PSD had greater treatment persistence (48.9%) and longer treatment duration (8.7 ± 4.4 months) than those with OPD (22.4% and 5.4 ± 4.3 months) and NPD (22.2% and 4.9 ± 4.7 months) (P < 0.01 for all; number needed to treat, 3). In last-observation-carried-forward analyses, patients with PSD had greater percent baseline weight loss at 12 months (5.1% ± 9.3%) than patients with OPD and with NPD (2.7% ± 5.5% and 2.4% ± 6.3%); greater percent BMI loss at 9 and 12 months than both groups (P < 0.05 for all) and greater BMI loss at 9 months (2.1 ± 3.5 kg/m2) and 12 months (2.3 ± 4.1 kg/m2) than NPD patients (1.1 ± 2.3 and 1.2 ± 2.4 kg/m2). Furthermore, weight loss of 5% or more occurred in 42.6% of patients with PSD versus 18.4% and 23.0% in OPD and NPD patients (P < 0.01 for all; numbers needed to treat, 5 and 6). The strongest weight loss predictor was treatment duration (β = 0.51–0.54; P < 0.001). Attrition was predicted by NPD (P = 0.001) and OPD group status (P = 0.036), lower proportion of group sessions (P = 0.002), higher depression (P = 0.028), and lower baseline BMI (P = 0.030).
Conclusions: Patients with PSD had greater weight loss than other obese patients. Nonadherence and depression should be targeted to enhance weight loss success.