Background:Lupus nephritis (LN) is classified by renal biopsy into proliferative and nonproliferative forms,with distinct prognoses,but renal biopsy is not available for every LN patient.The present study aimed to establish an altate tool by building a predictive model to evaluate the probability of proliferative LN.Methods:In this retrospective cohort with biopsy-proven LN,382 patients in development cohort,193 in intemal validation cohort,and 164 newly diagnosed patients in extal validation cohort were selected.Logistic regression model was established,and the concordance statistics (C-statistics),Akaike information criterion (AIC),integrated discrimination improvement,Hosmer-Lemeshow test,and net reclassification improvement were calculated to evaluate the performance and validation of models.Results:The prevalence of proliferative LN was 77.7％ in the whole cohort.A model,including age,gender,systolic blood pressure,hemoglobin,proteinuria,hematuria,and serum C3,performed well on good-of-fit and discrimination in the development chohort to predict the risk of proliferative LN (291 for AIC and 0.84 for C-statistics).In the intal and extal validation cohorts,this model showed good capability for discrimination and calibration (0.84 and 0.82 for C-statistics,and 0.99 and 0.75 for P values,respectively).Conclusion:This study developed and validated a model including demographic and clinical indices to evaluate the probability of presenting proliferative LN to guide therapeutic decisions and outcomes.