Weight Gain During Long-Term Treatment of Obsessive-Compulsive Disorder: A Prospective Comparison Between Serotonin Reuptake Inhibitors

Background: The effect of extended antidepressant treatment on weight has been poorly investigated. Also unknown is whether different compounds have differential effects. The aim of the present study was to assess changes in weight in obsessive-compulsive disorder (OCD) patients treated for 2.5 years with clomipramine or selective serotonin reuptake inhibitors.

Method: 138 DSM-IV OCD patients who responded to 6-month acute treatment at the Mood and Anxiety Disorders Unit, Department of Neuroscience, University of Turin, Italy, were followed-up for 2 years while receiving open-label clomipramine, citalopram, fluoxetine, fluvoxamine, paroxetine, or sertraline. Patients were consecutively recruited and followed from May 1998 to March 2003. The mean percentage change in weight was compared for each group, as was the proportion of patients who had a >= 7% weight increase from baseline.

Results: At the end of the 2.5-year study period, patients had gained a mean of 2.5% of their body weight with respect to baseline (1.58 kg); 14.5% of the total sample experienced a significant (>= 7%) weight increase. Within each but the fluoxetine treatment group, paired t tests showed a significant increase in weight from baseline to final visit. Analysis of variance showed a significant difference between treatment groups (p– = .009), with clomipramine being associated with the highest weight increase and fluoxetine and sertraline with the lowest. A higher proportion of clomipramine-treated patients (34.8%) gained >= 7% in weight as compared with sertraline and fluoxetine, which accounted for the lowest percentage of patients with a significant weight gain (4.5% and 8.7%, respectively), although this difference was not statistically significant.

Conclusion: Risk of weight gain during extended serotonin reuptake inhibitor treatment for OCD differs depending on which compound is used. The differences among antiobsessive drugs may affect compliance with medication and health risks.