Prevalence and prognostic significance of extrarenal manifestations in patients with lupus nephritis: A retrospective cohort study

Objectives To evaluate the prevalence and prognostic implications of extrarenal involvement in lupus nephritis (LN), with emphasis on treatment response and the risk of future renal and extrarenal flares. Methods We retrospectively reviewed patients newly diagnosed with LN between January 2006 and December 2022 and categorized them according to the presence of extrarenal involvement at diagnosis. Renal response and remission at 12 months, defined according to the Definition of Remission in SLE (DORIS), as well as the incidence of renal and extrarenal flares during follow-up, were compared between groups. Factors associated with DORIS remission and renal response were assessed using multivariable logistic regression analyses. Results Among 348 patients with LN, 156 (44.8%) had extrarenal involvement at diagnosis, most commonly hematological manifestations (59.0%). Rates of complete renal response (CRR) and DORIS remission at 12 months were comparable between patients with and without extrarenal involvement (CRR: 57.1% vs. 46.9%, p = 0.06; DORIS remission: 21.8% vs. 29.7%, p = 0.09). Over a median follow-up of 79.6 months, the incidence of renal flares (28.8% vs. 26.0%, p = 0.56) and extrarenal flares (26.3% vs. 24.5%, p = 0.74) did not differ significantly between groups. In multivariable analyses, baseline extrarenal involvement was not associated with DORIS remission (odds ratio [OR], 1.307; 95% confidence interval [CI]: 0.779–2.193; p = 0.310) or renal response (OR, 0.974; 95% CI: 0.564–1.682; p = 0.925). Conclusions Extrarenal involvement is present in nearly half of patients at LN diagnosis, however, it does not appear to influence renal response, DORIS remission, or the long-term risk of renal or extrarenal flares.