Prediction model for renal outcomes in Latin American Mestizo patients with pure proliferative lupus nephritis.

Abstract

Objective: Lupus nephritis (LN) is associated with a poorer prognosis in Latin American populations. However, the contributing risk factors contributing to this remain to be fully elucidated. This study aimed to develop a prognostic model for poor renal outcomes in patients of mestizo descent.

Methods: We conducted a multicentre, retrospective analysis including 290 adult mestizo patients with incident, biopsy-proven pure proliferative LN (International Society of Nephrology/Renal Pathology Society (ISN/RPS) class III or IV) from nine Chilean hospitals. Clinical, biological and histological variables were assessed. The primary outcome was a composite of stage IV/V chronic kidney disease, dialysis or death. Predictive variables were selected using multivariable Cox regression, and prognostic scores were derived accordingly. Internal validation was performed via bootstrapping. External validation included 93 Mexican patients, with model performance assessed using Harrel's concordance index.

Results: Two baseline factors were independently associated with poor renal outcome: estimated glomerular filtration rate <30 mL/min/m² (HR 3.82, 95% CI 2.15 to 6.78; p<0.001) and histological chronicity index >2 (HR 2.01, 95% CI 1.18 to 3.43; p=0.01). Patients were stratified into three risk categories according to the presence of none (low risk), one (intermediate risk) or both (high risk) of these factors. The likelihood of the primary outcome increased progressively across these groups: high versus intermediate risk (HR 3.22, 95% CI 1.64 to 6.34; p=0.001), and intermediate versus low risk group (HR 2.41, 95% CI 1.35 to 4.30; p=0.003). The three-tier model was replicated in the validation cohort with a concordance index of 79% (95% CI 71% to 87%; p<0.001) between predicted and observed results.

Conclusions: Based on two readily available features at the time of diagnosis, the proposed model effectively stratifies Latin American mestizo patients with pure proliferative LN (ISN/RPS class III or IV) into three risk categories for poor renal outcome. This tool may support improved risk-based management in this high-risk population.