Clinical and Biochemical Factors Associated with Delayed Renal Response in Proliferative Lupus Nephritis: A 20-Year Single-Center Multiethnic Cohort Study

<b>Background/Objectives</b>: Renal response remains underexplored across ethnic groups in the Asia-Pacific region; Malaysia, being a multiethnic country, provides a unique setting to examine these variations within the same healthcare system. This study was conducted to identify the clinical and biochemical characteristics and factors associated with renal response in Malaysia's multiethnic LN population. <b>Methods</b>: A retrospective cohort study of biopsy-proven proliferative LN episodes between 2000 and 2020 was conducted. Baseline clinical, laboratory, and treatment variables were extracted from medical records. Each relapse was analyzed as a separate episode. Partial and complete renal responses (PRR/CRR) at 6, 12, and 24 months were recorded. Predictors of early complete remission (CR), defined as CRR at 12 months while on prednisolone ≤ 10 mg daily, were identified using a generalized estimating equations (GEE) analysis. <b>Results</b>: A total of 212 LN episodes in 145 patients were included. Most episodes occurred in Malay (61.3%), Chinese (34.9%), and Indian (3.8%) patients. The rates of CRR/PRR at 6, 12, and 24 months were 34.9%/35.4%, 23.6%/47.6%, 14.6%/61.3%, respectively. In multivariable GEE analyses, delayed induction (OR 4.19), relapse LN episode (OR 3.91), comorbid hypertension (OR 3.51), and Malay ethnicity (OR 3.23) were associated with delayed complete remission. In contrast, achievement of any remission (partial or complete) at 6 months was protective against delayed CR at 12 months. <b>Conclusions</b>: Our findings underscore the importance of early induction therapy and relapse prevention in LN, as both are key predictors of renal response. The observed ethnic disparities warrant confirmation in larger prospective studies to elucidate potential factors and underlying genetic influences of renal response among the diverse ethnic groups.