Association between red blood cell distribution width-to-albumin ratio and prognosis in non-ischaemic heart failure

Aims Red blood cell distribution width-to-albumin ratio (RAR), an innovate biomarker of inflammation, can independently predict adverse cardiovascular outcomes. However, the association between RAR and prognosis in patients with non-ischaemic heart failure (NIHF) remains unclear.Methods and results A total of 2077 NIHF patients admitted to the Heart Failure Care Unit, Fuwai Hospital, were consecutively enrolled from December 2006 to October 2017 in this retrospective study. The primary endpoint was a composite outcome of all-cause mortality and heart transplantation. The correlation between RAR and the composite outcome was assessed by the Kaplan-Meier survival analysis and the Cox regression analysis. Incremental predictive values and the clinical performance of RAR for all-cause mortality or heart transplantation were also assessed based on a 12-variable traditional risk model. The median follow-up time in this study was 1433 (1341, 1525) days. As the gender no longer satisfied the Cox proportional risk assumption after 1150 days, we set 1095 days as the follow-up time for analysis. A total of 500 patients reached the composite outcome. Multivariable Cox regression showed that per log(2) increase of RAR was significantly associated with a 132.9% [hazard ratio 2.329, 95% confidence interval (CI) 1.677-3.237, P < 0.001] increased risk of all-cause mortality or heart transplantation. Better model discrimination [concordance index: 0.766 (95% CI 0.754-0.778) vs. 0.758 (95% CI 0.746-0.770), P < 0.001], calibration (Akaike information criterion: 1487.3 vs. 1495.74; Bayesian information criterion: 1566.25 vs. 1569.43; Brier score: 1569.43 vs. 1569.43; likelihood ratio test P < 0.001), and reclassification (integrated discrimination improvement: 1.35%, 95% CI 0.63-2.07%, P < 0.001; net reclassification improvement: 13.73%, 95% CI 2.05-27.18%, P = 0.034) were improved after adding RAR to the traditional model (P < 0.001 for all). A higher overall net benefit was also obtained in the threshold risk probability of 20-55%.Conclusions High level of RAR was an independent risk factor of poor outcome in NIHF.