Importance: Giant cell arteritis (GCA) is the most common vasculitis in adults and is associated with significant morbidity and mortality. Its incidence has been carefully studied in white populations, yet its relevance among other racial and ethnic groups is less well known. Objective: To examine the incidence of biopsy-proven GCA (BP-GCA) in a tertiary care center-based population with a sizeable proportion of black patients. Design, Setting, and Participants: This retrospective cohort study identified all patients who underwent temporal artery biopsy (TAB) from July 1, 2007, through September 30, 2017, using the electronic medical record system at the Johns Hopkins Wilmer Eye Institute. Associations between self-reported race, sex, and age were explored and compared with all other patients attending the hospital over the same period. Data were analyzed from November 1, 2017, through July 31, 2018. Main Outcomes and Measures: Estimated incidence rates of BP-GCA in black and white patients. Results: Among 586 patients who underwent TAB (mean [SD] age, 70.5 [11.1] years; age range, 32-103 years; 423 [72.2%] women), 167 (28.5%) were black, 382 (65.2%) were white, and 37 (6.3%) were other or unknown. Of 573 individuals 50 years and older, 92 (16.1%) had BP-GCA; 14 were black (8.4% of all black patients undergoing testing) and 75 were white (19.6% of all white patients undergoing testing). Crude annual incidence rates for BP-GCA were 2.9 (95% CI, 1.3-5.5) per 100000 for black and 4.2 (95% CI, 3.0-5.6) per 100000 for white patients within the study population. Population-adjusted age- and sex-standardized incidence rates were 3.1 (95% CI, 1.0-5.2) and 3.6 (95% CI, 2.5-4.7) per 100 000 for black and white patients, respectively (difference, 0.5; 95% CI, -1.7 to 2.7; P =.70). The incidence rate ratio was 1.9 in women compared with men (95% CI, 1.1-3.4; P =.03) but was not significant in white compared with black patients (1.2; 95% CI, 0.6-2.4; P =.66). Conclusions and Relevance: In our cohort, BP-GCA occurred more commonly in women, but rates were similar between races. These findings do not appear to support the conclusion that GCA occurs more frequently in white compared with black patients.
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