Background/Purpose: Rheumatoid arthritis (RA) is a systemic inflammatory disease affecting about 1.5 million adults in the US (Helmick et al., 2008). Patients with RA have an increased burden of comorbidity such as cardiovascular disease (CVD), diabetes, cancer, and other inflammatory diseases. This study aimed to update prevalence estimates of RA and associated comorbidity in the US.

Methods: This was a retrospective descriptive study using the 2010-2015 20% Medicare sample data. Yearly prevalent RA cohorts (2011-2015) were defined based on ICD-9 diagnosis code 714.0 with the addition of ICD-10 codes for the 2015 cohort. For each cohort year, included patients were required to have Medicare Part A and Part B coverage with no Medicare Advantage, and to be alive for the entire year preceding a cohort year and through the first month of the cohort year. RA was defined if a diagnosis code was present in at least 1 inpatient claim or 2 or more outpatient claims, separated by at least 30 days. The baseline period was 1 year preceding the cohort year and was used to define comorbidity, including CVD, diabetes, hypertension, hyperlipidemia, cancer, anemia, and other inflammatory conditions such as psoriasis, psoriatic arthritis, non-alcoholic fatty liver disease (NAFLD), and cirrhosis. Prevalence of comorbidity was presented as a percentage of RA patients.

Results: This study included approximately 6 million Medicare beneficiaries in each year, 2011-2015; average RA prevalence was about 2.0% (Table 1). RA patient demographics were similar across years, with mean age 72.4 years; 77.0% were female, 83.4% white, and 10.7% black in the 2015 cohort. Common comorbid conditions in the 2015 RA cohort included hypertension (prevalence 67.3%), hyperlipidemia (48.5%), diabetes (26.6%), anemia (26.4%), arteriosclerotic heart disease (21.5%), peripheral artery disease (17.2%), congestive heart failure (13.2%), and cancer (8.8%) (Table 1). Prevalence of inflammatory conditions increased across years; for example, NAFLD was 0.96% in 2011 and 1.36% in 2015; corresponding values were 0.04% and 0.07% for cirrhosis, 1.14% and 1.45% for psoriasis, and 1.58% and 1.81% for psoriatic arthritis.

Table 1. Prevalence of RA and Associated Comorbid Conditions in 2011-2015 Medicare Patients

Conclusion: Hypertension, CVD, hyperlipidemia, diabetes, anemia, and cancer are common in RA patients. Other inflammatory conditions increased over the years studied. Further analysis should evaluate the effect of RA treatment and of secondary prevention in patients with other inflammatory conditions.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-rheumatoid-arthritis-and-associated-comorbidities-in-the-2011-2015-medicare-population/