Objective: The frequency of coronary heart disease (CHD) and stroke are increased in systemic lupus erythematosus (SLE), but the extent of the increase is uncertain. We sought to determine to what extent the increase could not be explained by common risk factors.
Methods: The participants at two SLE registries were assessed retrospectively for the baseline level of the Framingham study risk factors and for the presence of vascular outcomes: nonfatal myocardial infarction (MI), death due to CHD, overall CHD (nonfatal MI, death due to CHD, angina pectoris, and congestive heart failure due to CHD), and stroke. For each patient, the probability of the given outcome was estimated based on the individual's risk profile and the Framingham multiple logistic regression model, corrected for observed followup. Ninety-five percent confidence intervals (95% CIs) were estimated by bootstrap techniques.
Results: Of 296 SLE patients, 33 with a vascular event prior to baseline were excluded. Of the 263 remaining patients, 34 had CHD events (17 nonfatal MIs, 12 CHD deaths) and 16 had strokes over a mean followup period of 8.6 years. After controlling for common risk factors at baseline, the increase in relative risk for these outcomes was 10.1 for nonfatal MI (95% CI 5.8-15.6), 17.0 for death due to CHD (95% CI 8.1-29.7), 7.5 for overall CHD (95% CI 5.1-10.4), and 7.9 for stroke (95% CI 4.0-13.6).
Conclusion: There is a substantial and statistically significant increase in CHD and stroke in SLE that cannot be fully explained by traditional Framingham risk factors alone.