While ankylosing spondylitis may be more common among whites, black patients have more comorbidities and express higher disease activity, Dilpreet Kaur Singh, MD, and Marina Magrey, MBBS, reported in The Journal of Rheumatology.

A retrospective review of a large U.S. medical database conducted by Dr. Singh and Dr. Magrey of MetroHealth Medical Center, Cleveland, found that black patients had higher erythrocyte sedimentation rates and C-reactive protein, and a higher prevalence of anterior uveitis, hypertension, diabetes, and depression, compared with white patients. (Dr. Singh, who was a rheumatology fellow at MetroHealth at the time of the study, is now a practicing rheumatologist in Springfield, Mass.)

Disease severity in AS is “thought to be genetically mediated but cultural, social, or economic factors may also be contributing to this racial disparity,” the investigators wrote. “Further research is needed to determine the role of factors other than genetic factors like HLA-B27 positivity that contribute to worsening disease severity.”

The authors extracted data recorded during 1999-2017 from the Explorys platform, a clinical research informatics tool with data from more than 50 million patients in 26 major integrated health care systems in the United States.

The current study comprised 10,990 AS patients with at least two visits to a rheumatologist. Most (84%) were white; 8% were black. Sex was equally distributed in both groups. Positivity for HLA-B27 was similar among whites (26%) and blacks (20%). A majority of patients smoked (65%), and smoking was more common among whites than among blacks (67% vs. 59%).

Disease characteristics suggested that AS was more severe among blacks. Significantly greater proportions of black patients had elevated erythrocyte sedimentation rate (62% vs. 48% of whites) and C-reactive protein (68% vs. 54%). Blacks also experienced significantly greater rates of anterior uveitis (8% vs. 4%), hypertension (29% vs. 22%), diabetes (27% vs. 17%), and depression (36% vs. 32%).

Blacks experienced higher rates of peripheral arthritis, enthesopathy, dactylitis, and inflammatory bowel disease, although these differences were not statistically significant when compared with whites.

Whites, however, had significantly higher rates of psoriasis (10% vs. 6.5%).

Most of the cohort (87%) received NSAIDs; 39% used tumor necrosis factor inhibitors. There were no significant between-group treatment differences.

The authors reported no potential conflicts of interest and no source of financial support.

SOURCE: Singh DK et al. J Rheumatol. 2019 Sep 1. doi: 10.3899/jrheum.181019.