Compared with White Americans, African American patients with ankylosing spondylitis (AS) have higher disease activity and increased frequency of comorbidities, according to study results published in The Journal of Rheumatology.

Using the Explorys platform, which aggregates data from 26 major integrated healthcare systems in the United States, the investigators aimed to describe the racial differences in the clinical characteristics and comorbidities among African American and White patients with AS.

Data from 10,990 patients with AS were identified, of whom 84% were White and 8% were African American. Approximately half of the patients in each group were male (P =.17). A total of 25% of patients with AS tested positive for HLA-B27, which was more frequently observed in White (26%) compared with African American patients (20%), though this difference was not significant (P =.11).

An elevated erythrocyte sedimentation rate was more frequently observed in African American (62%) compared with White patients (48%; P <.0001). Similar results were seen for C-reactive protein levels (68% vs 54%; P <.0001). In addition, anterior uveitis was more frequently observed in African American (7.6%) vs White patients (4%; P <.0001).


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The prevalence of several comorbidities were also significantly higher in African American compared with White patients, including hypertension (29% vs 22%; P <.0001), diabetes (27% vs 17%; P <.0001), and depression (36% vs 32%; P =.02). However, psoriasis (10% vs 6.5%; P =.002) was more frequently observed in White compared with African American patients.

A majority of patients were treated with nonsteroidal anti-inflammatory drugs and tumor necrosis factor inhibitors; however, prescription rates did not vary between White and African American patients.

Investigators noted that the true proportion of HLA-B27 positivity in the African American and White populations was underestimated in the Explorys database, which represented a limitation of the study. The true expected proportion has been observed to be 50% to 60% in African American and 90% in White patients, which the researchers confirmed using electronic records from their institution (MetroHealth Medical Center, Cleveland, Ohio). In this subgroup analysis of 101 patients with AS, 64% of White and 42% of African American patients tested positive for HLA-B27.

“[D]espite low prevalence of AS in African American patients, African Americans tend to have elevated levels of markers of inflammation and anterior uveitis, and more comorbidities,” the researchers concluded. “An improved risk stratification and vigilance for early diagnosis and treatment of AS particularly in African American patients is needed.”

Reference

Singh DK, Magrey MN. Racial differences in clinical features and comorbidities in ankylosing spondylitis in the United States. J Rheumatol. 2020;47(6):835-838.