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Patients with SLE are at increased risk for HF, not just of MI and stroke, with risk similar to that of patients with diabetes, researchers found in an analysis of Medicaid data.
It is known that patients with SLE have an elevated risk for atherosclerotic cardiovascular disease, but most studies have focused on MI and stroke as cardiovascular outcomes, so little is known about these patients' risks for HF, which can represent the final stage of cardiac disease, with high morbidity and mortality, explained Sarah K. Chen, MD, of Brigham and Women's Hospital in Boston, and colleagues.
The goal of the study was to determine the risk of patients with systemic lupus erythematosus (SLE) for incident heart failure (HF), compared with HF risk in patients with type 2 diabetes, and with the general Medicaid population.
It is known that patients with SLE have an elevated risk for atherosclerotic cardiovascular disease, but most studies have focused on MI and stroke as cardiovascular outcomes, so little is known about these patients' risks for HF, which can represent the final stage of cardiac disease, with high morbidity and mortality, explained Sarah K. Chen, MD, of Brigham and Women's Hospital in Boston, and colleagues
Chen and colleagues investigated the rates of incident HF and hospitalization in patients among these two groups, comparing them with rates in age- and sex-matched controls from the general Medicaid population.
Their study included patients enrolled in Medicaid from 2007 to 2010: 37,902 with SLE, 76,657 with diabetes, and 158,695 matched controls. A total of 93% in each group were women, and mean age was 40.
During a mean follow-up of 1.9 years, researchers found 479 hospitalizations for HF among patients with SLE, 921 during 1.8 years for those with diabetes, and 397 during 1.6 years among controls.
The incidence rate of HF was 6.9 (95% CI 6.3-7.5) per 1,000 person-years among patients with SLE, 6.6 (95% CI 6.2-7) per 1,000 among patients with diabetes, and 1.6 (95% CI 1.5-1.8) per 1,000 in the general Medicaid population, the group reported in Seminars in Arthritis & Rheumatism.
And in a fully adjusted multivariate analysis, the risk of hospitalization for HF was almost three-fold higher, at 2.7 (95% CI 2.3-3.1) for SLE, and 3.0 (95% CI 2.6-3.4) for diabetes compared with the general Medicaid population.
Notably, researchers saw differences in rates of hospitalization when the groups were stratified according to age. For SLE patients, the incidence rate was 6.1 (95% CI 5.3-7) per 1,000 person-years in the 18-39 age group compared with 2.8 (95% CI 2.4-3.2) for those with diabetes. In the 40-49 age group, the rate was 6.2 (95% CI 5.2-7.4) per 1,000 for SLE and 7.3 (95% CI 6.5-8.2) per 1,000 for diabetes, and for the 50-65 age group, the rate was 8.7 (95% CI 7.4-10.2) per 1,000 for SLE and 13.1 (95% CI 12.0-14.4) for diabetes.
Unadjusted incidence rate ratios compared with controls were similar for SLE and diabetes, at 4.65 (95% CI 4.31-4.50) and 4.44 (95% CI 4.31-4.57), respectively.
However, in the youngest 18-39 age group, the incidence rate ratio (IRR) for heart failure was 14.70 (95% CI 13.92-15.53) for SLE compared with 6.68 (95% CI 6.32-7.06) for diabetes, whereas in the older age groups, IRRs were slightly higher with diabetes than SLE.
"These data suggest that patients with SLE are at risk for a condition associated with significant morbidity and mortality at a much younger age than patients from the general population or with diabetes mellitus," the researchers noted.
The final multivariable risk model adjusted for multiple potentially important confounders, including hypertension, renal disease, Charlson comorbidity index, and atherosclerotic cardiovascular disease. In an unadjusted analysis, the hazard ratio (HR) was 4.2 (95% CI 3.6-4.7) for SLE, but it remained at 2.7 in the fully adjusted model, "suggesting that these risk factors do not fully explain the increased heart failure risk in SLE," they said.
Other studies have indicated that incident heart failure in the general population is highest among black patients versus those of other races. Chen's group also found that the incident rate for HF was indeed highest among black patients in all three cohorts, including the SLE cohort. Even with adjustment in the multivariate model for race/ethnicity among other demographic factors, SLE patients were still found to have a 4.2-fold increased risk of incident HF hospitalization versus the general Medicaid patients, and a similar risk compared with diabetes patients.
A study limitation was its reliance on administrative claims data.