Background/Purpose: Real-world benefits of belimumab (BL) in patients with SLE have been shown using SLE-specific measures.^1,2 As SLE disease activity measurement is challenging,³ assessment of treatment effectiveness using other measures is important. Routine Assessment of Patient Index Data 3 (RAPID3) questionnaire assesses SLE in patients with RA and is a valid measure of SLE disease⁴. This study used real-world data from United Rheumatology Normalized Integrated Community Evidence (UR-NICE) to assess intravenous (IV) BL in improving outcomes.

Methods: Adults with SLE in UR-NICE database who initiated IV BL between January 1, 2012–December 3, 2019, and had ≥5 subsequent BL infusions were included. Patients had SLE clinical activity recorded in the database for ≥12 months before and ≥24 months after first IV BL. Primary objective was time to minimally important difference (MID) from 12 months before index to 24 months post index, measured by Patient Pain Index (PPI), RAPID3, Tender Joint Count (TJC), Swollen Joint Count (SJC), Complement (C)3, C4, and anti-dsDNA. Outcomes were assessed in patients with ≥1 record of that measure during baseline/follow-up. MID was 0.5x the standard deviation of mean baseline values for each disease measure.⁵ Kaplan–Meier rates of time to first decrease below/increase above MID were reported during follow-up (3, 6, 12, 18, and 24 months).

Results: Of the 495 patients, >50% were in the PPI, C3, and C4 subgroups, ~30% in the TJC, SJC, and anti-dsDNA subgroups, and 21% in the RAPID3 subgroup.

Improvements in PPI were observed early and continued; 42.6% reached decrease below MID at 3 months, 55.0% at 6 months, and 76.4% at 24 months. For RAPID3 scores, decreases below MID were achieved by 36.5% at 3 months and 61.5% at 24 months. Decrease below MID in TJC was 16.7% at 3 months, which more than doubled to 35.4% at 12 months, and improved through 24 months. Decrease below MID in SJC almost doubled between 3 and 24 months (11.5% to 21.6%), although swollen joints were not as prevalent as tender joints at baseline.

Increase above MID for C3 and C4 levels, respectively, was 8.7% and 8.8% ≤3 months of treatment, increasing to 55.2% and 46.4% at 24 months. Anti-dsDNA levels improved after treatment initiation, with decrease below MID doubling between 3 and 6 months (7.8% to 15.6%).

Conclusion: Among patients initiating IV BL therapy, meaningful improvement in outcomes assessed with multiple rheumatology disease measures, including RAPID3, can be seen as early as 3 months, incrementally increasing over time. While laboratory measures are used to show the rapid effect of BL treatment, this study demonstrated symptomatic improvement in patient pain, physical function, and tender/swollen joints among BL-treated patients with SLE.

References
1. Collins CE, et al. Rheumatol Ther. 2020;7(4):949–65.
2. Levy RA, et al. Lupus. 2021;30(11):1705–21.
3. Mikdashi J, et al. Arthritis Res Ther. 2015;17(1):1–10.
4. Annapureddy N, et al. Lupus. 2018;27(6):982–90.
5. Ousmen A, et al. Health Qual Life Outcomes. 2018;16(1):1–12.

Content reprinted from the STAR Annual Meeting, February 3–5, 2023. Worley K, et al. Changes in Rheumatology Disease Measures after Initiation of Belimumab Treatment in Patients With Systemic Lupus Erythematosus.

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