The features of systemic lupus erythematosus (SLE) are common in the lifetime course of rheumatoid arthritis (RA) and are significantly associated with an increased mortality risk, even after adjusting for well-described RA-specific predictors of mortality. For some SLE features, the increased risk may be as high as 6-fold.
Icen and colleagues studied 603 persons with incident RA. Data on disease characteristics, therapy, comorbidities, and SLE features were gathered from inpatient and outpatient medical records.
The percentage of patients with RA estimated to have a second SLE feature (in addition to arthritis) was 87.8% at 20 years and 89.5% at 25 years. Over 25 years of follow-up, an estimated 54.5% of patients had 3 SLE features, 15.5% had 4 features, and 5% had 5 features. The age- and sex-adjusted hazard risk for mortality in patients with 2 or 3 and 4 or more SLE features compared with those having only arthritis were 1.85 (95% confidence interval [CI], 1.37 to 2.49) and 5.54 (95% CI, 3.59 to 8.53), respectively. Most SLE features were individually associated with mortality, after adjusting for age and sex.
The authors noted that clinicians should remain alert to manifestations of autoimmunity and overlapping disease features even well after the diagnosis of RA is established.