Use of Framingham risk score and new biomarkers to predict cardiovascular mortality in older people: population based observational cohort study

Abstract

Objectives: To investigate the performance of classic risk factors, and of some new biomarkers, in predicting cardiovascular mortality in very old people from the general population with no history of cardiovascular disease.

Design: The Leiden 85-plus Study (1997-2004) is an observational prospective cohort study with 5 years of follow-up.

Setting: General population of the city of Leiden, the Netherlands.

Participants: Population based sample of participants aged 85 years (215 women and 87 men) with no history of cardiovascular disease; no other exclusion criteria. Main measurements Cause specific mortality was registered during follow-up. All classic risk factors included in the Framingham risk score (sex, systolic blood pressure, total and high density lipoprotein cholesterol, diabetes mellitus, smoking and electrocardiogram based left ventricular hypertrophy), as well as plasma concentrations of the new biomarkers homocysteine, folic acid, C reactive protein, and interleukin 6, were assessed at baseline.

Results: During follow-up, 108 of the 302 participants died; 32% (35/108) of deaths were from cardiovascular causes. Classic risk factors did not predict cardiovascular mortality when used in the Framingham risk score (area under receiver operating characteristic curve 0.53, 95% confidence interval 0.42 to 0.63) or in a newly calibrated model (0.53, 0.43 to 0.64). Of the new biomarkers studied, homocysteine had most predictive power (0.65, 0.55 to 0.75). Entering any additional risk factor or combination of factors into the homocysteine prediction model did not increase its discriminative power.

Conclusions: In very old people from the general population with no history of cardiovascular disease, concentrations of homocysteine alone can accurately identify those at high risk of cardiovascular mortality, whereas classic risk factors included in the Framingham risk score do not. These preliminary findings warrant validation in a separate cohort.

Fig 1 Cumulative cardiovascular mortality depending on tertiles of risk obtained from classic risk factors, weighted on the basis of Framingham risk score, or newly calibrated risk score from the Leiden 85-plus Study

Fig 2 Cumulative cardiovascular mortality depending on tertiles of risk obtained from prediction models using homocysteine, folic acid, C reactive protein and interleukin 6

Fig 3 Receiver operating characteristic curves showing performance of three prediction models for 5 year cardiovascular mortality based on Framingham risk score, homocysteine concentrations only, and homocysteine concentrations plus Framingham risk score