C-reactive protein and 5-year survival in type 2 diabetes: the Casale Monferrato Study

Abstract

Objective: To determine to what extent plasma C-reactive protein (CRP) values influence 5-year all-cause and cardiovascular mortality in type 2 diabetic individuals, independently of albumin excretion rate (AER) and other cardiovascular risk factors, and its incremental usefulness for predicting individual risk of mortality.

Research design and methods: Measurements of CRP were performed in 2,381 of 3,249 (73.3%) subjects as part of the population-based Casale Monferrato Study. Its association with 5-year all-cause and cardiovascular mortality was assessed with multivariate Cox proportional hazards modeling. The C statistic and measures of calibration and global fit were also assessed.

Results: Results are based on 496 deaths in 11.717 person-years of observations (median follow-up 5.4 years). With respect to subjects with CRP < or =3 mg/l, those with higher values had an adjusted hazard ratio (HR) of 1.51 (95% CI 1.18-1.92) for all-cause mortality and 1.44 (0.99-2.08) for cardiovascular mortality. In normoalbuminuric subjects, respective HRs of CRP were 1.56 (1.13-2.15) and 1.65 (1.00-2.74), AER being neither a modifier nor a confounder of CRP association. In analysis limited to diabetic subjects without cardiovascular disease (CVD), adjusted HRs were 1.67 (1.24-2.24) for all-cause mortality and 1.36 (0.83-2.24) for cardiovascular mortality. The improvement in individual risk assessment was marginal when measured with various statistical measures of model discrimination, calibration, and global fit.

Conclusions: CRP measurement is independently associated with short-term mortality risk in type 2 diabetic individuals, even in normoalbuminuric subjects and in those without a previous diagnosis of CVD. Its clinical usefulness in individual assessment of 5-year risk of mortality, however, is limited.

FIG. 1.

Kaplan-Meier curves depicting the survival curves of the cohort by CRP levels (dotted line CRP ≤3 mg/l, solid line >3 mg/ml). Log-rank test P < 0.001.