Natural-cause mortality and C-reactive protein levels in patients with schizophrenia spectrum disorders: A prospective total cohort study.

Background: Schizophrenia spectrum disorders (SSD) are associated with an excess mortality risk compared with the general population. The involvement of low-grade inflammation and elevated C-reactive protein (CRP) levels is well established in SSD. However, associations between CRP and mortality risk in SSD are less investigated. Aim: To investigate the association between the baseline CRP level and natural-cause mortality risk in SSD. Methods: We included all patients with an SSD diagnosis and baseline CRP measurement from an open cohort study of consecutively admitted patients to a psychiatric acute unit at Haukeland University Hospital, Bergen, Norway, between May 1, 2005 and June 15, 2014. All patients were followed until the time of death or censoring/study end, up to 18.6 years, and only the assessments at admission were the focus of the present study. A competing risk model was used, adjusting for age and sex. Results: Among 1315 individuals, 245 (19 %) died of natural causes; among these patients, 66 (27 %) deaths were related to cardiovascular disease (CVD). Elevated baseline CRP levels of 1.0 ≤ CRP <3.0 mg/L were significantly associated with increased natural-cause mortality risk (adjusted hazard ratio [AHR], 1.88; 95 % confidence interval [CI], 1.22-2.88; p-value, 0.004), with a stronger association for CRP ≥3.0 mg/L (AHR, 2.28; 95 % CI, 1.50-3.48; p-value, <0.001), compared with patients with CRP <1.0 mg/L. Moreover, baseline CRP ≥3.0 mg/L was associated with increased CVD-related mortality risk (AHR, 3.12; 95 % CI, 1.16-8.41; p-value, 0.024). Conclusions: Elevated CRP levels were associated with increased natural-cause mortality and, specifically, with CVD-related mortality risk. The CRP level may thus be considered a predictive factor in mortality risk scoring algorithms in SSD.