Increased Morbidity and Mortality of Scleroderma in African Americans Compared to Non-African Americans.

Abstract

African Americans with scleroderma have more severe disease and higher mortality than non-African Americans. Differences in rates of diffuse disease, autoantibody status, or socioeconomic status have not completely explained this phenomenon. Our study evaluates these risks at our site. A retrospective study comparing African American and non-African American patients with scleroderma seen from 2008 to 2016 was performed. Groups were matched by sex, age at first visit, date of first visit, disease duration at first visit, and limited versus diffuse cutaneous disease. Demographic, serologic, and clinical features were compared. Mortality risks were assessed by a Cox proportional hazards model with covariates of race, marital status, education, employment, insurance, and imputed household income. African Americans comprised 202 of 402 patients. They demonstrated reduced forced vital capacity and diffusing capacity for carbon monoxide, more severe lung fibrosis, a higher prevalence of pulmonary hypertension, and more severe cardiac involvement. The autoantibody profile statistically differed between the 2 groups. Death during follow-up was 21% in African Americans versus 11% in non-African Americans (P = 0.005). African American race demonstrated an unadjusted hazard ratio for death during follow-up of 2.061 (P = 0.006) that declined with adjustment for socioeconomic covariates to 1.256 (P = 0.633). The only significant covariate was median income in tens of thousands of dollars by zip code (hazard ratio 0.845; P = 0.033). African American patients with scleroderma have more severe pulmonary disease and higher unadjusted mortality than matched non-African Americans. Following adjustment for socioeconomic factors, African American race was not a significant risk factor for mortality; however, independent of race, a lower median household income predicted increased mortality.