Mortality and cardiovascular burden of systemic lupus erythematosus in a US population-based cohort

Abstract

Objective: To examine the mortality and cardiovascular disease (CVD) burden among a population-based cohort of patients with systemic lupus erythematosus (SLE) with previously described late mean onset and low rates of organ-threatening disease.

Methods: This retrospective population-based cohort study investigated incident cases of SLE diagnosed from 1991-2008 and followed through March 2009 to examine rates of death and CVD events: myocardial infarction, stroke, or congestive heart failure hospitalization. Cases were identified using the 1997 update of the 1982 American College of Rheumatology SLE criteria. Searches included electronic records, chart audits, and state death matches, with physician review. Age-matched and sex-matched population comparisons facilitated relative event rate calculations.

Results: Seventy incident SLE cases had late mean onset (52 years), with an incidence of 5 cases per 100,000/year. Matched comparisons showed similar baseline rates of hypertension, hyperlipidemia, and diabetes. However, patients with SLE experienced more CVD in the 2 years preceding SLE diagnosis (OR 3.8, 95% CI 1.8, 8.0). The estimated 10-year mortality rates were 26% for SLE subjects versus 19% for comparisons, hazard ratio (HR) 2.1, p<0.01. Adjusted for prior CVD, SLE cases still demonstrated increased hazards of mortality (HR 1.9, p=0.01) and CVD event or death (HR 1.8, p=0.01).

Conclusion: This incident SLE cohort demonstrated nearly doubled mortality and CVD event hazards compared to age-matched and sex-matched comparisons, even after accounting for higher CVD events in the 2 years preceding SLE diagnosis. This raises research questions regarding delayed SLE diagnosis versus accelerated CVD prior to SLE, particularly in older-onset SLE.

Keywords: CARDIOVASCULAR SYSTEM; COHORT STUDY; EPIDEMIOLOGY; INCIDENCE; MORTALITY; SYSTEMIC LUPUS ERYTHEMATOSUS.

Figure 1

Clinical SLE features at baseline (Panel A) and medication exposure history (Panel B). Values reflect percent of SLE patients (n=70) with each feature.

Figure 2

Kaplan-Meier estimates for SLE cases and their age and sex-matched comparisons for (A) all-cause mortality and (B) the composite of death or CVD event. SLE subjects had 2-fold increased hazards for each endpoint (A and B).

Figure 3

Kaplan-Meier estimates for SLE cases and their age and sex-matched comparisons for (A) all-cause mortality and (B) the composite of death or CVD event endpoints stratified by baseline CVD status. Increased hazard ratios of SLE for event risk remained even after stratifying for baseline CVD status.