Background/Purpose: Background/Purpose: Randomized controlled trials (RCTs) in SLE identify specific populations of interest for eligibility, but still vary in the recruited populations.  These differences may include the baseline disease activity level, laboratory findings, baseline treatment medication use, and racial mix. Previously presented data highlight regional differences in SLE populations which in turn may influence treatment responses. This study analyzed the demographics and baseline disease characteristics of randomized SLE patients across three different RCTs conducted through our organization.

Methods: We evaluated combined screening data from three recently enrolled SLE RCTs post hoc. Eligibility criteria were targeted at the enrollment of patients with active SLE meeting ACR classification criteria (SELENA-SLEDAI ≥8 for two studies of ~700 and 850 patients each, and SLEDAI-2K ≥6 for the third study of ~300 patients). Two studies were globally recruited, one was regional. Patients with varying degrees of severely active lupus nephritis or neuropsychiatric SLE were excluded. Differences between each combination of two study populations were evaluated via a two-tailed t-test for disease duration, corticosteroid use, immunosuppressant use, complement and anti-dsDNA status.

Results: Of the 1854 randomized patients, 50.1% were Asian; 38.8%, white; and 5.7%, black; and 93.4% were female.  Details regarding treatment medications (corticosteroids, immunosuppressants, antimalarials), SLEDAI scores (total, clinical); anti-dsDNA, ANA, and C3/C4 status are presented in Table 1 and regarding subjects meeting each SLEDAI criterion in Table 2.  Mycophenolate (20.0%) was the most common immunosuppressant used, followed by azathioprine (15.8%) and then methotrexate (9.5%). Differences existed between each study population at the p<0.001 level for the percentage of subjects on corticosteroids, on immunosuppressants (except for a nonsignificant difference between the two global studies); with hypocomplementemia, with elevated anti-dsDNA titers or with both.

Conclusion: SLE patients enrolled in RCTs, despite having similar levels of disease required by the SLEDAI, varied in critical baseline laboratory characteristics and standard of care medications. These differences may have resulted from variables such as study size and regional aspects, e.g., racial mix, standard of care; and may impact treatment responses. Further differences in disease activity by region and race are being evaluated. Understanding such differences may influence the design of SLE RCTs moving forward.