Background/Purpose:

Ethnic heterogeneity of the United States (US) population makes it imperative to study the racial differences in clinical characteristics of Ankylosing Spondylitis (AS) patients, a disease mainly considered to be of Caucasians with HLA-B27 predominance. We hypothesize that African Americans (AA) have more severe disease compared to Caucasians in the US.

Methods:

Data was collected using Explorys universe, a clinical research informatics tool that uses unified medical language system ontologies to standardize, normalize and aggregate clinical data from 26 US major healthcare systems that use Epic from 1999 to present comprising of over 50 million patients. De-identified data are presented through a secure web interface. The Power Search tool was utilized to create refined cohorts with specific search criteria. We identified 28, 520 patients with AS. This was further stratified by having at least two rheumatology visits; adding race, gender, clinical characteristics, medication use or co-morbidity diagnoses to the search tool. Data sets were recorded as proportions, which were compared using chi-squared test (p<0.05).

Results:

10,990 AS patients with at least two rheumatology visits of all races were identified of whom 50% were males. 84% of AS patients were Caucasian, whereas 8% were AA. Half of both races were males (p=0.17). 25% of the AS cohort tested for HLA-B27 were positive (26% Caucasians vs 20% AA, p = 0.11). Subgroup analysis of 101 AS patient records at our institution identified 78% HLA-B27 positive patients (64% Caucasians vs 42% AA, p=0.0018).

65% of AS patients were smokers (67% Caucasians vs 59% AA, p<0.0001). A greater proportion of AA had elevated erythrocyte sedimentation rate (62% AA vs 48% Caucasians, p < 0.0001) and C-reactive protein levels (68% AA vs 54% Caucasians, p < 0.0001). 73% of AS patients had peripheral arthritis (74% Caucasians vs 76% AA, p= 0.15), 25% had enthesopathy (26% Caucasian vs 27% AA, p = 0.18), 10% had psoriasis (10% Caucasians vs 7% AA, p=0.0002) and inflammatory bowel disease (11% Caucasian vs 12% AA, p = 0.23), 4% had anterior uveitis (4% Caucasians vs 8% AA, p < 0.0001) and 5% had dactylitis (5% Caucasian vs 7% AA, p = 0.09). Majority (87%) of the AS patients were treated with nonsteroidal antiinflammatory drugs (87% Caucasians vs 89% AA, p=0.62) and 39% used TNF-α inhibitors (40% Caucasian vs 37% AA, p<0.08). AA compared to Caucasians had higher prevalence of hypertension (29% vs 22%, n=2,350, p<0.0001), diabetes (27% vs 17%, n=1,940, p<0.0001), depression (36% vs 32%, n=3,380, p=0.02) and heart disease (24% vs 22%, n=2,290, p=0.11). Caucasians compared to AA had higher prevalence of fibromyalgia (14% vs 12%, n=1,480, p=0.07) and osteoporosis (18% vs 16%, n=1890, p=0.36).

Conclusion:

Our findings from a large US electronic database confirm that AS is more prevalent in Caucasians with equal proportion of males and females between both races. Markers of inflammation, anterior uveitis and co-morbidities were significantly higher in AA. There was no significant difference in the use of TNF-α inhibitors. Study limitation was that Explorys could not capture the true proportion of HLA-B27 positivity due to it being a send out test with results not being electronically available in Epic.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/racial-differences-in-clinical-characteristics-and-co-morbidities-of-ankylosing-spondylitis/