Selective Serotonin Reuptake Inhibitors and Serotonin Norepinephrine Reuptake Inhibitors and Body Mass Index in Patients on Long Term Treatment: A Cross-Sectional Comparative Study

Background: Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin Norepinephrine Reuptake Inhibitors (SNRIs) are the most commonly prescribed antidepressants but changes in body weight (BW) is a concern with the chronic use of antidepressant. We observed the effect of SSRIs and SNRIs on BW and body mass index (BMI) in patients on long-term therapy while avoiding the other confounding factors. Objectives: To assess and compare the changes in BW and BMI in patients on monotherapy with either SSRIs (escitalopram, sertraline or fluoxetine) or SNRIs (duloxetine, venlafaxine or desvenlafaxine). Methods: In a cross-sectional, hospital-based, comparative study, the patients on monotherapy with sertraline, fluoxetine, escitalopram, venlafaxine, desvenlafaxine or duloxetine for a period of ≥ 24 weeks were evaluated for the changes in their BW and BMI. In patients showing a change in weight, causality assessment was done by Naranjo’s algorithm and severity assessment by modified Hartwig and Siegel scale. Results and Conclusion: Fifty-eight patients were included (SSRIs = 30; SNRIs = 28). Escitalopram and sertraline were associated with increases in BW and BMI, whereas fluoxetine, duloxetine, venlafaxine, and desvenlafaxine showed reductions. Median weight gain with escitalopram and sertraline was 2.0kg (IQR 1.5) and 2.0kg (IQR 1.0), respectively. Fluoxetine showed mean reductions of 1.20 ± 1.32kg in BW and 0.44 ± 0.50kg/m² in BMI. Statistically significant changes were observed with SSRIs but not with SNRIs. Between-group analysis demonstrated significantly greater weight gain with SSRIs compared with weight reduction with SNRIs (p < 0.001). All changes were classified as probable and mild. As weight changes remained <5 of baseline BW over ≥ 24 weeks, they may not be considered clinically meaningful. These findings suggest that SSRIs and SNRIs have a relatively favourable weight profile in patients without significant comorbidities or concomitant medications.