Cross-sectional and longitudinal analysis of high-sensitivity C-reactive protein as a biomarker for suicidal behavior in depressive patients undergoing pharmacotherapy

This study investigated the role of serum high-sensitivity C-reactive protein (hsCRP) as a biomarker for suicidal behavior (SB) in both cross-sectional and longitudinal contexts, driven by emerging evidence that systemic inflammation, marked by elevated hsCRP levels, may be linked to increased suicidality in individuals with depressive disorders. Serum hsCRP levels were measured at baseline in 1,094 patients with depressive disorders. Of these, 884 were followed during a 12-month period of stepwise pharmacotherapy. SB assessments included previous suicide attempts and baseline suicidal severity at baseline, and increased suicidal severity and fatal/non-fatal suicide attempts at follow-up. We analyzed the associations between hsCRP levels (and elevated levels ≥1.0 mg/L) with these SB categories using logistic regression, adjusting for relevant covariates. Higher or elevated serum hsCRP levels were significantly associated with SB at baseline in cross-sectional analyses. However, these associations did not persist in the 12-month longitudinal analyses after adjustments. While hsCRP serves as a concurrent biomarker for SB, it does not act as a predictive marker for future suicidal behaviors. Future research should include repeated measures of hsCRP in a controlled setting to confirm these findings.