In patients with systemic lupus erythematosus receiving rituximab and belimumab, Black and Indo-Asian patients were less likely to obtain major clinical response.
While the absolute reduction in disease activity was comparable across ethnicities in patients with systemic lupus erythematosus (SLE), achieving major clinical response after initiation of treatment was lower in Black and Indo-Asian patients, according to data presented at the European Congress of Rheumatology (EULAR) 2023.1 This may be in part attributed to higher baseline disease activity in these patient populations; however, it could not be explained by level of social deprivation and the observation was not confined to a single treatment. Investigators emphasized the need for further research exploring the drivers of these inequitable outcomes as well as a reassessment of treat-to-target strategies in these patient populations.
In addition to a lower likelihood of achieving major clinical response, other research has shown racial and ethnic minorities with lupus were more likely to develop kidney, neurological, and blood manifestations when compared with White patients.2 They were also at a greater risk of developing severe manifestations such as lupus nephritis, antiphospholipid syndrome, and thrombocytopenia earlier than White patients.
To describe the different responses of patients with moderate-to-severe SLE in the United Kingdom (UK) according to ethnic background, investigators analyzed patients with SLE initiating rituximab, belimumab, or standard of care in the British Isles Lupus Assessment Group-Biologics Register (BILAG-BR) trial over a 12-month period.
Major clinical response was defined as Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) ≤4 at the end of the study period. Deprivation was measured using the English indices of deprivation 2019 decile (EID), in which a score of 1 means the most deprived and 10 is the least deprived. The major clinical response was compared using multivariate logistic regression, with the reference group comprised of White patients; adjusted for age, gender, and EID. Missing data were accounted for using random forest in R V4.2.1.
Between September 2010 and September 2022, 1601 patients with SLE initiated therapy. Most (90.4%, n = 1447) patients were female and the median age was 39.9 (31.0 – 50.6) years. Most (n = 1177) patients initiated rituximab, 193 received belimumab, and 231 received standard of care. Regarding ethnicity, 56.5% (n = 905) were White, 14.6% (n = 233) were Black, 197 patients were Indo-Asian, 5.1% (n = 81) were Chinese/East Asian, and 60 patients were categorized as multiple/mixed background. A total of 7.8% (n = 125) preferred not to disclose their ethnicity. Most (85.2%, n = 1364) patients were receiving glucocorticoids at baseline, with a median dose of 7 (4.5 – 11.1) mg daily.
At 12 months, approximately half (56.3%, n = 901) of patients achieved major clinical response. At baseline, Black patients had a higher SLEDAI-2K score when compared with White patients. Black, East Asian/Chinese, and multiple/mixed background patients received a higher glucocorticoid dose at baseline. Additionally, Black, Indo-Asian, and multiple/mixed background patients were more likely to be categorized in a lower EID.
In the rituximab cohort, Black (adjusted odds ratio [OR] .36 [95% confidence interval (CI) .25 – .52]) and Indo-Asian (.42, [.18 – .96]) patients were less likely to achieve major clinical response. For those receiving belimumab, Black (.65 [.44 – .96]) and Indo-Asian patients (.29 [.09 – .93]) were also less likely to obtain major clinical response. However, absolute reduction in SLEDAI-2K was similar across ethnic groups.