[Clinical factors related to gains in body mass index (BMI) among patients under long-term antipsychotic treatment].

Objective: Weight gain and obesity are often seen among patients taking antipsychotic drugs, the incidence being higher in this group than among the general adult population. They constitute risk factors for other diseases, such as hyperlipidemia, type 2 diabetes mellitus and hypertension, and may also adversely affect a patient's compliance. Thus the control of weight gain and obesity is significantly related to the quality of life for those who are under long-term antipsychotic treatment. We therefore conducted a retrospective investigation on the process of BMI increase in patients treated with antipsychotic agents over an extended period. The BMI of these patients was compared with measurements in the general adult population and the clinically relevant factors contributing to weight gain were identified.

Method: The subjects were 66 outpatients (35 males, 31 females; mean age 37.5 +/- 11.9 y.o., range 15-65 years) who satisfied the F2 category of the ICD-10 diagnostic criteria, and who were on antipsychotic drugs for more than 2 years and less than 15 years. The study was conducted at two psychiatric clinics between May 1, 2000 and June 1, 2001. The results of the survey were analyzed as follows: 1) The BMI of the subjects was compared against that of the controls who visited the Health Center, the Jikei Hospital from 1999 to 2002 to observe time-related trends over the study period; and 2) The odds ratio was computed using a logistic regression model with the mean of the changes in BMI during treatment as a dependent variable and clinically related factors, gender, age, diagnosis, clinical outcome, duration of treatment, baseline BMI, and type and dose of antipsychotic drugs as independent variables, to determine those factors contributing to the gain in BMI.

Results: 1) When the patients' ages were stratified, there were no significant differences between the male patients and the corresponding standard, either for the baseline or recent BMI at each age level, with the exception of the 15-39 age level. Among female patients, there were no significant differences for the baseline BMI at any age level. However, the recent BMI for them was significantly higher at all age levels. 2) In the study of factors related to increase in BMI, 3 factors--gender, age, and complete remission in clinical outcome--were found to have significant difference. The odds ratio was significantly higher in the female subjects (4.94; 95% CI: 1.42-17.27) and significantly lower in older subjects (0.93; 95% CI: 0.88-0.99), and in those subjects who were in complete remission (0.081; 95% CI: 0.007-0.954). No other factors produced statistically significant differences.

Discussion: 1) Gender, age, and clinical outcome were the independent factors that contributed to the increase in BMI for those patients under long-term antipsychotic treatment. 2) The gain in BMI was greater in female patients than in male patients. 3) Age was inversely related to the gain in BMI, therefore special care must be taken after administering antipsychotic drugs because younger patients may gain excessive weight and develop weight-related complications at an earlier stage. 4) The increase in BMI was minimal for patients in complete remission, suggesting that these patients were better adapted socially and aware of maintaining an optimum BMI. In planning antipsychotic treatment for each patient, not only its efficacy on psychiatric symptoms but also the risks--such as an increase in BMI--should be taken into consideration.