Kidney outcomes in pure membranous versus proliferative lupus nephritis: A 14-year Latin American cohort study

BackgroundPure membranous lupus nephritis (MLN) generally has a better kidney prognosis than proliferative lupus nephritis (PLN), but comparative data from Latin America remain limited. We evaluated clinical features and kidney outcomes of MLN in a Colombian cohort and compared them with proliferative forms.MethodsWe retrospectively included adults (≥18 years) with first biopsy-proven MLN or PLN at a Colombian tertiary center. Clinical and histopathological features were compared between pure MLN (Class V) and PLN (Class III/IV ± V). Factors associated with MLN were analyzed using logistic regression. Kidney survival was estimated using Kaplan-Meier analysis, and predictors of end-stage kidney disease (ESKD) were assessed using Cox proportional hazards regression analyses. Because death could preclude observation of ESKD, competing-risks analyses were performed using cumulative incidence functions and Fine-Gray subdistribution hazard models with death treated as a competing event.ResultsOf 371 patients, 54 (14.6%) had MLN and 317 (85.4%) had PLN. Compared with PLN, patients with MLN have lower immunological activity, better kidney function, less active urinary sediment at biopsy, and lower modified NIH activity and chronicity indices scores. In multivariable logistic regression, higher eGFR was independently associated with MLN (OR 1.02, 95% CI 1.01-1.03), whereas anti-dsDNA positivity was inversely associated (OR 0.33, 95% CI 0.15-0.71). In univariable Cox analysis, MLN was associated with lower ESKD risk (HR 0.12, 95% CI 0.03-0.48); but this association was not confirmed in multivariable analysis, which was underpowered because only 2 ESKD events occurred in the MLN group. In competing-risks analysis, MLN was associated with a lower unadjusted subdistribution hazard of ESKD (SHR 0.13, 95% CI 0.03-0.51), but not after adjustment for baseline eGFR and modified NIH indices (adjusted SHR 0.46, 95% CI 0.11-2.00). Kaplan-Meier analysis showed higher crude renal survival in MLN than in PLN.ConclusionIn this Latin American cohort, MLN exhibited a distinct baseline profile characterized by lower inflammatory activity and better-preserved kidney function at presentation. Although crude and competing-risk analyses suggested a more favorable renal trajectory for MLN, the study was underpowered to confirm an independent effect of MLN on ESKD after adjustment.