Evidence for an association between inflammatory markers and suicide: A cohort study based on 359,849 to 462,747 Taiwanese adults

[[abstract]]BACKGROUND: Biological markers of suicide risk have the potential to inform prevention and treatment efforts. It has recently been hypothesised that inflammation may influence mood and in turn suicide risk. We investigated the association between indicators of systemic inflammation and suicide in a large cohort of Taiwanese adults. METHODS: White blood cell (WBC) count and levels of C-reactive protein (CRP) were measured in 462,747 and 359,849 adults in the Taiwan MJ cohort, respectively. The associations between WBC, CRP and suicide risk were investigated using Cox proportional hazards models adjusting for a range of potential confounding factors. RESULTS: During a mean 15.1 and 15.8 years of follow-up, 687 and 605 suicides were identified in participants who had information on WBC and CRP respectively. There was an association of suicide with WBC count (adjusted hazard ratio [aHR] = 1.13 per 1 standard deviation increase of log-transformed WBC, 95% confidence interval [CI] 1.05, 1.22). The association was driven by the highest quintile of WBC count (aHR = 1.39, 95% CI 1.09, 1.77; reference: the lowest quintile). No association between CRP and suicide was found. LIMITATIONS: Our cohort was from a privately-run health check-up programme and had a lower suicide rate than that in the general population. CONCLUSIONS: Individuals with the highest WBC counts may have increased risk of suicide. Peripheral markers of inflammation are potential biomarkers of suicide risk; however, this seems to vary by population and the marker investigated and could be influenced by a range of confounding factors