Evaluation of objective nutritional indices as predictors of renal progression in IgA nephropathy patients

Immunoglobulin A nephropathy (IgAN) is a clinical and pathological syndrome with heterogenous manifestation and progression. The prognostic nutritional index (PNI) and the controlling nutritional status (CONUT) score, indicators of nutritional status and systemic inflammation, are associated with poor prognosis in dialysis patients. This study was aimed to investigate the predictive value of the objective nutritional indices (PNI and CONUT) for renal progression in IgAN patients.

A multicenter retrospective study was conducted in biopsy-proven IgAN patients. Baseline characteristics were obtained within 1 week before renal biopsy. The renal composite endpoint comprised an estimated glomerular filtration rate (eGFR) decline >50%, a doubling of baseline serum creatinine, or the occurrence of end stage kidney disease (ESKD). The receiver operating characteristic curve analysis was conducted to determine the optimal cut-off value of PNI and CONUT. The Kaplan-Meier curve estimated the cumulative renal-survival rate. Univariate and multivariate Cox regression models were preformed to investigate the association between objective nutritional indices and renal outcomes.

A total of 659 IgAN patients participated in this study. During a median follow-up period of 45 months, 68 patients (10.32%) achieved the composite endpoint. The Kaplan-Meier curve revealed that renal-survival rate was significantly higher in high PNI group (PNI > 46.5; p < 0.001) and low CONUT group (CONUT ≤2; p < 0.001). Even after adjustment of traditional risk factors, including sex, age, mean arterial pressure, hemoglobin, uric acid, eGFR, triglycerides, 24-h urinary protein, E score, T score, and treatment with ACEI/ARB, low PNI [hazard ratio (HR) = 2.514, 95% confidence intervals (CI) = 1.212-5.215, p = 0.013] and high CONUT (HR = 2.152, 95% CI = 1.087-4.259, p = 0.028) remained as independent risk factors for poor renal outcomes.

This study suggested that low PNI and high CONUT were significantly and independently correlated with poor prognosis in patients with IgAN at CKD stages 1-4. The PNI and CONUT are inexpensive and straightforward indicators to help clinicians improve IgAN management.