Epidemiologic Study Compares SLE Manifestations in Different Racial Groups

Racial and ethnic makeup can influence a patient’s risk of developing clinical or severe manifestations in systemic lupus erythematosus (SLE) after diagnosis, according to research published in Arthritis Care and Research.

Using data from the California Lupus Surveillance Project, researchers retrospectively identified 724 patients with SLE to analyze racial and ethnic differences in lupus manifestations and assess the timing and risk for severe disease manifestation. Data collected were from residents of San Francisco County, California, between 2007 and 2009.

The racial/ethnic breakdown of the patient population was 26.2% white, 18.8% black, 36.9% Asian-Pacific Islander (API), and 15.5% Hispanic. Twenty-six patients were excluded from the study because of missing race/ethnicity information or missing date of last clinic visit. The study population was 89.5% women.

In general, researchers did not note any statistically significant differences in age at diagnosis (P =.341) or sex  (P =.735); however, SLE duration among the included race/ethnicities was significant. White patients were more likely to have ≥16 years of follow-up from the time of diagnosis (44% vs 15%-30% for other groups; P <.001). Blacks and APIs were more likely to have lupus nephritis (20% and 52%, respectively, vs 13%-14% among other groups) and thrombocytopenia (24% and 39%, respectively, vs 17%-19% among other groups).

In comparison with white patients, black patients, APIs, and Hispanics experienced an increased prevalence for renal manifestations (prevalence ratios [PRs] 1.74, 1.68, and 1.35, respectively). Black patients also had an increased prevalence for neurologic (PR 1.49) and hematologic (1.09) manifestations. APIs also had an increased prevalence of hematologic manifestations (PR 1.07).

Researchers did not note any statistically significant differences in prevalence for mucocutaneous, serositis, cardiovascular, pulmonary, gastrointestinal, musculoskeletal, or serologic manifestations.

All 3 racial/ethnic minority groups had an elevated risk of developing lupus nephritis and thrombocytopenia (lupus nephritis hazard ratio [HR] 2.4; 95% CI, 1.6-3.8 for non-Hispanic blacks; HR 4.3; 95% CI, 2.9-6.4 for APIs; and HR 2.3; 95% CI, 1.4-3.8 for Hispanics, respectively; thrombocytopenia HR 2.3; 95% CI, 1.1-4.4 for blacks; HR 2.3; 95% CI, 1.3-4.2 for APIs; and HR 2.2; 95% CI, 1.1-4.7 for Hispanics). In addition, APIs and Hispanics also had an increased risk of developing antiphospholipid syndrome (HR 2.5; 95% CI, 1.4-4.4 for APIs and HR 2.6; 95% CI, 1.3-5.1 for Hispanics).

When assessed by sex, men with SLE had between 1.4× and 2.1× the HR of developing lupus nephritis or thrombocytopenia. The researchers found no statistically significant differences in the HR for severe SLE manifestations by age at SLE diagnosis or significant difference in the proportion of severe manifestations at diagnosis by race or ethnicity.

The researchers reported several limitations to this study, including incomplete case ascertainment because of surveillance efforts focusing on rheumatology instead of primary care clinics; quality of medical record documentation of SLE manifestations and criteria; and race and ethnicity determined via medical records and not patient self-report.

“Data collected in this study support the importance of increased awareness of SLE and its accelerated progression by clinicians for these racial/ethnic groups,” the researchers of the study noted. “Future studies should attempt to collect and analyze data on additional risk factors, including socioeconomic status, access to care, medication and appointment adherence, [and] coexisting medical conditions,” among others, they concluded.

Reference

Maningding E, Dall’Era M, Trupin L, Murphy LB, Yazdany J. Racial/ethnic differences in prevalence of and time to onset of SLE manifestations: the California Lupus Surveillance Project (CLSP) [published online May 22, 2019]. Arthritis Care Res. doi:10.1002/acr.23887