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

Objectives: Proliferative lupus nephritis (LN) is not uncommon in individuals with proteinuria < 0.5 g/24h, highlighting the importance of predicting proliferative nephritis for effective clinical management. We aimed to develop a predictive model for proliferative nephritis 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: 103 of 671 (15.4%) LN patients had low-level proteinuria, while 43 (41.7%) of whom showed proliferative LN, and the activity index and chronicity index were 5 (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-double strands DNA 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: 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.