Smoking and weight among patients using clozapine.

Background: Both obesity and smoking are common in schizophrenia patients taking clozapine, causing cardiovascular disease and premature deaths.

Methods: Two hundred and thirty-seven patients with schizophrenia or related psychoses treated with clozapine completed the Liverpool University Neuroleptic Assessment Scale (LUNSERS) and a questionnaire including current height, weight, changes therein and smoking status.

Aims: The aim of this study was to analyze weight and weight change in smoking and non-smoking patients taking clozapine. A possible interaction between obesity and smoking was explored.

Results: No association was found between weight change and smoking status during clozapine treatment. There was no significant difference in body mass index (BMI) between non-smokers and smokers. In the analysis of covariance (ANCOVA) with BMI as the dependent variable, the best fitting model comprised age, sex, intensity of sedation, and reported amount of smoking as explanatory variables (ηp(2)= 0.116; P = 0.029; power = 0.750). None of the explanatory proportions of any single factor was significant.

Conclusions: Estimated according to reported weight gain and BMI, no difference was found between smoking and non-smoking clozapine-treated patients. Number of cigarettes smoked explained BMI if age and sex were taken into account. This result is in line with the findings of some general population studies, where heavy smoking has been associated with a greater risk of obesity.