Importance Obesity is associated with numerous psychosocial complications, making psychiatric safety a consideration for treating people with obesity. Few studies have investigated the psychiatric safety of newly available antiobesity medications.

Objective:

To evaluate the psychiatric safety of subcutaneous semaglutide, 2.4 mg, once weekly in people without known major psychopathology. Design, Setting, and

Participants:

This post hoc analysis of pooled data from the randomized, double-blind, placebo-controlled, multicenter phase 3a STEP 1, 2, and 3 trials (68 weeks; 2018-2020) and phase 3b STEP 5 trial (104 weeks; 2018-2021) included adults with overweight or obesity; STEP 2 participants also had type 2 diabetes. Trial designs have been published previously.

Interventions:

Semaglutide, 2.4 mg, vs placebo. Main Outcomes and

Measures:

Depressive symptoms and suicidal ideation/behavior were assessed using the Patient Health Questionnaire (PHQ-9) and Columbia-Suicide Severity Rating Scale, respectively. Psychiatric and nervous system disorder adverse events were investigated.

Results:

This analysis included 3377 participants in the STEP 1, 2, and 3 trials (2360 women [69.6%]; mean [SD] age, 49 [13] years) and 304 participants in STEP 5 (236 women [77.6%]; mean [SD] age, 47 [11] years). In the STEP 1, 2, and 3 trials, mean (SD) baseline PHQ-9 scores for the semaglutide, 2.4 mg, and placebo groups were 2.0 (2.3) and 1.8 (2.3), respectively, indicating no/minimal symptoms of depression. PHQ-9 scores at week 68 were 2.0 (2.9) and 2.4 (3.3), respectively; the estimated treatment difference (95% CI) between groups was -0.56 (-0.81 to -0.32) (P < .001). Participants treated with semaglutide vs placebo were less likely to shift (from baseline to week 68) to a more severe category of PHQ-9 depression (odds ratio, 0.63; 95% CI, 0.50-0.79; P < .001). Based on the Columbia-Suicide Severity Rating Scale, 1% or fewer of participants reported suicidal ideation/behavior during treatment, with no differences between semaglutide, 2.4 mg, and placebo. Psychiatric disorder adverse events were generally balanced between groups. Similar results were observed in STEP 5. Conclusions and Relevance The results of this post hoc analysis suggest that treatment with semaglutide, 2.4 mg, did not increase the risk of developing symptoms of depression or suicidal ideation/behavior vs placebo and was associated with a small but statistically significant reduction in depressive symptoms (not considered clinically meaningful). People with obesity should be monitored for mental health concerns so they can receive appropriate support and care. Trial Registration ClinicalTrials.gov Identifiers STEP 1 (NCT03548935), 2 (NCT03552757), 3 (NCT03611582), and 5 (NCT03693430).