Background/Purpose: Prevalence of systemic lupus erythematosus (SLE) has been estimated in different US regions. An estimate based on the 2005 US population showed SLE affecting 161,000-322,000 adults (Helmick et al., 2008). We aimed to update estimates of SLE prevalence and associated comorbidity in the US Medicare population.

Methods: We used the 2010-2015 20% Medicare sample data. For each year (2011-2015), we required patients to have Medicare Parts A/B coverage, not have Medicare Advantage, and be alive for the entire preceding year and through the first day of the year. Using ICD-9 diagnosis code 710.0 and ICD-10 codes M32.1, M32.8, and M32.9 (for 2015), we defined SLE by presence of a diagnosis code on ≥1 inpatient or ≥2 outpatient claims separated by ≥30 days. The baseline period, 1 year before each SLE cohort year, was used to define comorbid conditions including: anemia, chronic kidney disease (CKD), end-stage renal disease (ESRD), glomerulonephritis (GN), rheumatoid arthritis (RA), etc. SLE prevalence was reported as the number of SLE patients per 1000 Medicare population.

Results: We included ~6 million Medicare beneficiaries each year. Demographics and baseline characteristics were similar across years. In the 2015 cohort (Table 1), SLE patient mean age was 63.7 (±14.9) years, 89.4% were female, 21.9% were black; comorbidity percentages were 32.5% anemia, 26.0% CKD, 7.1% ESRD, and 17.9%  RA. Non-SLE patient mean age was 72.3 (±12.6) years, 56.9% were female, 9.4% were black; comorbidity percentages were 13.8% anemia, 11.3% CKD, 1.2% ESRD, and 1.9% RA. Average SLE prevalence was 3.4 (Table 2). Prevalence was higher for ages <45 years, women, and black patients, and for patients with baseline conditions. For example in 2014, SLE prevalence in patients with the following conditions was 37.6, GN; 31.6, RA; 20.5, ESRD; 13.6, psoriatic arthritis; 11.1, Crohn disease; and 10.5, liver disease.

Conclusion: Average SLE prevalence was 3.4 per 1000 Medicare beneficiaries. Prevalence in patients with kidney-related diseases or arthritis was 3-10 times the average. These results underscore the need for effective treatment and management of comorbid conditions and of SLE in the aging Medicare population.

Table 1. Baseline Characteristics and Comorbid Conditions in 2015 20% Medicare Sample

Table 2. Prevalence of SLE in 2011-2015 20% Medicare Sample, Overall and by Demographics and Selected Conditions