The effect of including cystatin C or creatinine in a cardiovascular risk model for asymptomatic individuals

The authors studied the incremental value of adding serum cystatin C or creatinine to the Framingham risk score variables (FRSVs) for the prediction of incident cardiovascular disease (CVD) among 6,653 adults without clinical CVD utilizing the Multi-Ethnic Study of Atherosclerosis (2000-2008). CVD events included coronary heart disease, heart failure, stroke, and peripheral arterial disease. Variables were transformed to yield optimal prediction of 6-year CVD events in sex-stratified models with FRSVs alone, FRSVs + cystatin C, and FRSVs + creatinine. Risk prediction in the 3 models was assessed by using the C statistic, and net reclassification improvement was calculated. The mean ages were 61.9 and 64.6 years for individuals with and without diabetes, respectively. After 6 years of follow-up, 447 (7.2%) CVD events occurred. In the total cohort, no significant change in the C statistic was noted with FRSVs + cystatin C and FRSVs + creatinine compared with FRSVs alone, and net reclassification improvement for CVD risk was extremely small and not significant with the addition of cystatin C or creatinine to FRSVs. Similar findings were noted after stratifying by baseline presence of diabetes. In conclusion, the addition of cystatin C or serum creatinine to FRSVs does not improve CVD risk prediction among adults without clinical CVD.