Vitamin D Deficiency and 3-Year Risk of New-Onset Depression After Metabolic and Bariatric Surgery: A Longitudinal Cohort Study

Vitamin D deficiency (VDD) is highly prevalent after metabolic and bariatric surgery (MBS) and has been associated with depression in the general population. However, whether VDD is associated with incident depression specifically in the post-MBS population remains unknown.

Using the TriNetX Global Collaborative Network, we conducted a retrospective cohort study of adults with a prior history of MBS who underwent serum 25-hydroxyvitamin D testing (2010–2024). Patients were classified into a VDD group (< 20 ng/mL) and a control group (≥ 30 ng/mL). Those with pre-existing depression were excluded, and a 6-month landmark period was applied. After 1:1 propensity score matching, the primary outcome was 3-year incident overall depression. Secondary outcomes included depressive episodes, recurrent depressive disorder, and a composite of suicidal behavior or intentional self-harm. Acute appendicitis served as a negative control outcome.

After matching, 11,805 pairs were analyzed. VDD was associated with a higher risk of overall depression (4.64% vs. 2.53%; HR 1.87, 95%CI 1.62–2.15, P < 0.001), depressive episodes (HR 1.82, P < 0.001), and recurrent depressive disorder (HR 1.97, P < 0.001). No significant difference was observed in suicidal behavior (P = 0.986) or acute appendicitis (P = 0.879), whereas healthcare utilization was slightly lower in the VDD group (HR 0.92, P < 0.001). Sensitivity analysis restricted to 2016–2024 yielded consistent results (HR 1.87, P < 0.001). Subgroup analyses confirmed this association in subgroup analyses.

VDD is associated with a significantly increased risk of incident depression after MBS, suggesting that vitamin D status may be a clinically relevant risk marker that warrants further prospective investigation.