Cardiovascular risk estimation in 2012: lessons learned and applicability to the HIV population

Abstract

Cardiovascular disease (CVD) risk assessment tools such as the Framingham Risk Functions, often called Framingham Risk Scores, are common in the evaluation of the CVD risk among individuals in the general population. These functions are multivariate risk algorithms that combine data on CVD risk factors, such as sex, age, systolic blood pressure, total cholesterol level, high-density lipoprotein cholesterol level, smoking behavior, and diabetes status, to produce an estimate (or risk) of developing CVD or a component of it (such as coronary heart disease, stroke, peripheral vascular disease, and heart failure) over a fixed period (eg, the next 10 years). These estimates of CVD risk are often major inputs in recommending drug treatments, such as agents to reduce cholesterol level. The Framingham Risk Functions are valid in diverse populations, at times requiring a calibration adjustment for proper applicability. With the realization that individuals with human immunodeficiency virus (HIV) infection often have elevated CVD risk factors, the evaluation of CVD risk for these individuals becomes a serious concern. Researchers have recently developed new CVD risk functions specifically for HIV-infected patients and have also examined the extension of existing Framingham Risk Functions to the HIV-infected population. This article first reviews briefly the Framingham Study and risk functions, covering their objectives, their components, evaluation of their performance, and transportability and validity on non-Framingham populations. It then reviews the development of CVD risk functions for HIV-infected individuals and comments on the usefulness of extending the Framingham risk equation to the HIV-infected population and the need to develop more-specific risk prediction equations uniquely tailored to this population.

Figure 1.

Observed and predicted rates of myocardial infarction by duration of combination antiretroviral treatment (CART). Observed rates are observed number of myocardial infarctions (MIs) divided by person-years of follow-up. Predicted rates are the sum of estimated individual predicted probabilities of MI. See Methods for details. Error bars are 95% confidence intervals, based on the Poisson distribution for observed rates and bootstrap resampling for the best estimate of the predicted rates. Reprinted from Law et al. [37] with permission of John Wiley & Sons.