Association of red blood cell distribution width and hemoglobin-to-RDW ratio with contrast-associated acute kidney injury in patients undergoing coronary angiography: A retrospective study

Background: Inflammation contributes to poor prognosis in cardiovascular diseases. A novel biomarker for systemic inflammation that has garnered attention is the red blood cell distribution width (RDW). This study is designed to explore potential associations between RDW and hemoglobin-to-RDW ratio (HRR) with contrast-associated acute kidney injury (CA-AKI).Methods: This study retrospectively analyzed 4054 patients undergoing coronary angiography (CAG). Linear regression models were employed to assess the relationships between RDW or HRR and the elevation of serum creatinine (Scr). The associations between RDW or HRR and CA-AKI were explored using restricted cubic spline and log-binomial regression analyses taking into account specific cutoff values and quintiles. Exploratory analyses were also conducted to further investigate these associations.Results: Among enrolled patients, the average age was 66.9 years and 34.3% were female. Notably, patients who developed CA-AKI tended to have higher RDW and lower HRR. Multivariable linear regression models demonstrated that RDW exhibited a positive association with Scr elevation (beta = 2.496, 95% confidence interval [CI] = 1.784-3.208), while HRR displayed a negative association (beta = -3.559, 95% CI = -4.243 to -2.875). Multivariable log-binomial regression models confirmed that both high RDW (RDW >= 13.8%) and low HRR (HRR < 8.9) were significantly associated with a higher risk of CA-AKI (RDW [>= 13.8% vs. <13.8%]: relative risk [RR] = 1.540, 95% CI = 1.345-1.762; HRR [<8.9 vs. >= 8.9]: RR = 1.822, 95% CI = 1.584-2.096). Exploratory analysis determined that such associations still existed regardless of age, gender, estimated glomerular filtration rate, or anemia.Conclusions: Elevated preoperative RDW and decreased HRR were significantly associated with CA-AKI in patients undergoing CAG.