Estimation of 10-Year Risk of Death from Coronary Heart Disease, Stroke, and Cardiovascular Disease in a Pooled Analysis of Japanese Cohorts: EPOCH-JAPAN

Aims: We aimed to develop and validate risk prediction models to estimate the absolute 10-year risk of death from coronary heart disease (CHD), stroke, and cardiovascular disease (CVD). Methods: We evaluated a total of 44,869 individuals aged 40-79 years from eight Japanese prospective cohorts to derive coefficients of risk equations using cohort-stratified Cox proportional hazard regression models. Discrimination (C-index) of the equation was examined in each cohort and summarised using random-effect meta-analyses. Calibration of the equation was assessed using Hosmer-Lemeshow chi-squared statistic. Results: Within a median follow-up of 12.7 years, we observed 765 deaths due to CVD (276 CHDs and 489 strokes). After backward selection, age, sex, current smoking, systolic blood pressure (SBP), proteinuria, prevalent diabetes mellitus, the ratio of total cholesterol to high-density lipoprotein cholesterol (TC/HDLC), interaction terms of age by SBP, and age by current smoking were retained as predictors for CHD. Sex was excluded in the stroke equation. We did not consider TC/HDLC as a risk factor for the stroke and CVD equations. The pooled C-indices for CHD, stroke, and CVD were 0.83, 0.80, and 0.81, respectively, and the corresponding p-values of the Hosmer-Lemeshow tests were 0.18, 0.003, and 0.25, respectively. Conclusions: Risk equations in the present study can adequately estimate the absolute 10-year risk of death from CHD, stroke, and CVD. Future work will evaluate the system as an education and risk communication tool for primary prevention of CHD and stroke.