Usefulness of risk scores to estimate the risk of cardiovascular disease in patients with rheumatoid arthritis

Abstract

Patients with rheumatoid arthritis (RA) have an excess burden of cardiovascular (CV) disease (CVD). CV risk scores for the general population may not accurately predict CV risk for patients with RA. A population-based inception cohort of patients who fulfilled 1987 American College of Rheumatology criteria for RA from 1988 to 2007 was followed until death, migration, or December 31, 2008. CV risk factors and CVD (myocardial infarction, CV death, angina, stroke, intermittent claudication, and heart failure) were ascertained by medical record review. Ten-year predicted CVD risk was calculated using the general Framingham and the Reynolds risk scores. Standardized incidence ratios were calculated to compare observed and predicted CVD risks. The study included 525 patients with RA aged ≥30 years without previous CVD. The mean follow-up period was 8.4 years, during which 84 patients developed CVD. The observed CVD risk was 2-fold higher than the Framingham risk score predicted in women and 65% higher in men, and the Reynolds risk score revealed similar deficits. Patients aged ≥75 years had observed CVD risk >3 times the Framingham-predicted risk. Patients with positive rheumatoid factor or persistently elevated erythrocyte sedimentation rates also experienced more CVD events than predicted. In conclusion, the Framingham and Reynolds risk scores substantially underestimated CVD risk in patients with RA of both genders, especially in older ages and in patients with positive rheumatoid factor. These data underscore the need for more accurate tools to predict CVD risk in patients with RA.

Figure 1

Comparison of observed and predicted 10 year risk of cardiovascular disease (CVD) according to deciles of predicted risk (clear bars) obtained from the Framingham risk score. The observed risk (black bars) was obtained using Kaplan-Meier methods.

Figure 2

Excess observed vs. predicted 10 year risk of cardiovascular disease (CVD) according to deciles of predicted risk obtained from the Framingham risk score. The mean predicted risk for each decile was subtracted from the Kaplan-Meier estimate of 10 year observed risk with a 95% confidence interval. The solid interval is the actual and the dashed interval was obtained by multiplying the Framingham predicted risk by the overall standardized incidence ratio of 1.8 in an attempt to improve calibration of the Framingham risk score estimates.