Nomogram for predicting proliferative lupus nephritis in patients with low-level proteinuria

Abstract Objectives Proliferative LN is not uncommon in individuals with proteinuria <0.5 g/24 h, highlighting the importance of predicting proliferative nephritis for effective clinical management. We aimed to develop a predictive model for proliferative LN in this population. Methods The enrolled 671 biopsy-proven LN patients were divided into low-level proteinuria (<0.5 g/24 h) and high-level proteinuria (≥0.5 g/24 h) groups. The clinical features, pathological characteristics and long-term outcomes of the two groups were compared. The least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression analysis were used to construct a predictive nomogram for proliferative nephritis in low-level proteinuria patients and internal validation was performed using bootstrap-resampling. Results One hundred and three of 671 (15.4%) LN patients had low-level proteinuria, 43 (41.7%) of whom showed proliferative LN; the Activity Index and Chronicity Index were 5 [interquartile range (IQR) (4, 7)] and 3 [IQR (2, 4)], respectively. The long-term adverse renal events-free survival was preferable in the low-level proteinuria group. The LASSO-logistic regression identified that age, sex, mean arterial pressure, haemoglobin, platelet, 24-h proteinuria and anti-dsDNA antibodies positivity were associated with proliferative nephritis in those with low-level proteinuria. The predictive model showed an area under curve of 0.900 (95% CI 0.840–0.960) and a bootstrapped result of 0.894 (95% CI 0.832–0.965), with good calibration. Conclusion Some 41.7% of the patients with low-level proteinuria exhibited proliferative LN when biopsied. The nomogram including clinical, urinary and laboratory parameters might help with the prediction of proliferative LN before biopsy among patients with low-level proteinuria.