Evaluation of objective nutritional indexes as predictors of worse outcomes in peritoneal dialysis patients

Abstract

Objectives: Objective nutritional indexes have been shown to predict prognosis in some clinical settings. We aimed to explore the predictive values of these indexes in patients undergoing peritoneal dialysis (PD).

Methods: This is a single-center retrospective observational study in patients undergoing PD. The controlling nutritional status (CONUT) score, prognostic nutritional index (PNI), and geriatric nutritional risk index (GNRI) were calculated at baseline. The primary outcome was all-cause mortality. The secondary outcome was new-onset cardiocerebrovascular disease (CVD) events. Univariate and multivariate Cox regressions were performed to investigate the association between confounding factors and outcomes. The optimal cutoff values were determined using a receiver operating characteristic curve analysis. We used the Kaplan-Meier curve to compare the outcomes according to the cutoff values. The area under the curve (AUC) was used to test discriminative power of these objective nutritional indexes.

Results: We analyzed 252 patients undergoing PD at our institution. On the Cox hazard analysis, the CONUT score, PNI, and GNRI were independently associated with all-cause mortality (CONUT: hazard ratio [HR]: 1.496; 95% confidence interval (CI), 1.241-1.804; P < 0.001; PNI: HR: 0.878; 95% CI, 0.815-0.946; P = 0.001; and GNRI: HR: 0.930; 95% CI, 0.885-0.978; P = 0.040) and CVD incidence (CONUT: HR: 1.385; 95% CI, 1.177-1.630; P < 0.001; PNI: HR: 0.885; 95% CI, 0.826-0.949; P = 0.001; and GNRI: HR: 0.936; 95% CI, 0.893-0.981; P = 0.005). In the Kaplan-Meier analysis, patients with a higher CONUT score and lower PNI had significantly higher incidence of all-cause mortality (17.7% versus 3.0%; P = 0.022; 24.3% versus 5.7%, P = 0.003, respectively). As for new-onset CVD, patients with a higher CONUT score, lower PNI, and lower GNRI had higher occurrence rates (19.4% versus 3.0%; P = 0.006; 28.7% versus 7.9%; P = 0.001; 24.4% versus 9.9%; P = 0.035, respectively). The largest AUC to predict all-cause mortality was the CONUT score (AUC: 0.733; 95% CI, 0.674-0.787). For CVD prevalence, the largest AUC was the PNI (AUC: 0.718; 95% CI, 0.658-0.773).

Conclusions: Objective nutritional indexes were independently associated with all-cause mortality and CVD events in patients undergoing PD. Moreover, assessments of the CONUT score and PNI may provide more useful predictive values than GNRI.

Keywords: Cardiocerebrovascular disease; Malnutrition; Mortality; Peritoneal dialysis.