Real-world effectiveness of belimumab in patients with lupus in China: RELIABLE observational cohort study protocol.

Introduction: The efficacy of belimumab in SLE has been demonstrated in randomised clinical trials, and its real-world effectiveness has been shown in studies in several countries. While belimumab was approved for treating SLE in China in 2019, data on its benefit in clinical practice are limited. This study will evaluate belimumab's effectiveness in China, using practical clinical measures, such as Lupus Low Disease Activity State (LLDAS), to add to the body of real-world evidence.

Methods and analysis: The Real-world Effectiveness of beLImumAB in patients with systemic Lupus Erythematosus in China (RELIABLE) is an ambidirectional, observational descriptive cohort study across approximately 15 centres in China. Adults with SLE newly initiating belimumab with ≥1 measure of all five LLDAS components (SLE Disease Activity Index-2000; no new lupus disease activity; Physician Global Assessment; prednisolone-equivalent dose; immunosuppressants/biologics use) in the 3 months preceding belimumab initiation (index date) will be eligible and retrospectively and/or prospectively enrolled, depending on data availability. The retrospective follow-up will be ≤6 months, and retrospective and prospective patients will have a maximum 24-month follow-up. The primary objectives will be to describe the proportion of patients achieving LLDAS at 12 and 24 months post-index. The key secondary objective will be to describe the proportion of patients achieving LLDAS and each component at 3, 6, 9 and 18 months post-index. All data will be analysed descriptively; a statistical estimand will be applied to account for intercurrent events expected in a real-world setting.

Ethics and dissemination: This study will comply with all applicable laws regarding patient privacy; institutional review board approval will be obtained before the study commencement.

Conclusions: This study will evaluate belimumab's effectiveness in patients with SLE initiating belimumab in clinical practice in China. Using LLDAS will provide clinicians with valuable insights into the impact of belimumab on the treat-to-target strategy with a relevant measure that can be repeated across the clinical practice.