Aims: C-reactive protein and depressive mood (DM) are novel risk factors for coronary heart disease (CHD). The goal of the present study was to assess possible combined effects of these factors on the prediction of a future fatal and non-fatal coronary event.
Methods and results: Baseline highly sensitive (hs) C-reactive protein and DM were analysed in 3021 apparently healthy male subjects aged 45-74 from three subsequent population based surveys (1984-95) of the MONICA-KORA Augsburg Cohort Study. During a median follow-up period of 7.7 years (IQR=6.9 years), 165 CHD events occurred. Risks of CHD were estimated from Cox proportional hazard models adjusted for age and survey and multiple risk factors. The age and survey adjusted interaction term of continuous hs-C-reactive protein by DM disclosed a significant effect (HR 1.03; 95% CI 1.00-1.06; P=0.037). A stratified analysis of subpopulations with (n=986) and without (n=2035) DM revealed that high hs-C-reactive protein (>3 mg/L) was predictive in the group with DM (HR 2.69; 95% CI 1.32-5.47) but was not significant in the low-level depression group (HR 1.55; 95% CI 0.89-2.69). Relative to the low C-reactive protein/no depression subgroup (n=712), high C-reactive protein/no depression (n=565) did not significantly predict a future CHD event. However, combined high C-reactive protein and DM (n=282) significantly predicted future CHD events (HR 2.91; 95% CI 1.25-2.18; P>0.0001).
Conclusion: In apparently healthy men, a DM substantially increases the power of elevated C-reactive protein to predict a subsequent myocardial infarction. Both conditions may share a common underlying mechanism.