Abstract Background Red cell distribution width (RDW) is a biomarker associated with anemia and inflammation, and is known to predict mortality in both cardiovascular diseases and sepsis. Respective predictive roles of RDW versus anaemia in sepsis outcomes of cardiovascular patients with bioprosthetic heart valves was unknown. Purpose To investigate and compare role of RDW versus iron-deficiency anemia in predicting risk of infective endocarditis in patients with bioprosthetic heart valves. Methods A retrospective cohort study was performed in a population-representative clinical registry of a metropolitan. A total of 437 patients (49.7% female, age 64.4 ± 13.7 years) with prior aortic and/or mitral surgical valvular replacements with bioprosthetic heart valves were included. Baseline data on laboratory measurement of RDW, as well as pre-existing iron-deficiency anemia (International Classification of Diseases coded) was collected. Primary endpoint was defined as incident occurrence of infective endocarditis. Patients aged below 18 years were excluded. Multivariable Cox proportional hazards regression was used to derive Hazards Ratio (HR) for the primary endpoint. Results 23 of patients had pre-existing iron-deficiency anemia at baseline (5.3%). Iron-deficiency anemia was significantly associated with increased RDW (P=0.005). Over mean follow up of 101.3 ± 65.5 months, 40 primary endpoints of infective endocarditis occurred (9.2%). 228 (52.2%) of patients died over the study period. Iron-deficiency anemia was a strong and significant predictor for incident infective endocarditis before (P0.001) and after adjustment for potential confounders (including age, sex, socioeconomic status, history of ischemic stroke, congestive heart failure, atrial fibrillation, serum creatinine (adjusted HR=4.8, 95%CI 1.97 to 11.70, 0.001, Figure 1). In contrast, RDW did not provide statistically significant prediction for the primary endpoint (C-statistic=0.51, P=0.82, Figure 2). Prediction of Fe-deficiency anemia for the primary endpoint remained unchanged after incorporating RDW into the multivariable model (HR=5.3, 95%CI 2.12 to 13.31, P0.001). No material change was observed after adjustment for competing risk of death (P=0.91) Conclusions Iron-deficiency anemia but not RDW, strongly and independently predicts risk of incident infective endocarditis in cardiac patients with bioprosthetic heart valves. Underlying mechanistic basis will require further investigations.Figure 1For image description, please refer to the figure legend and surrounding text. Figure 2For image description, please refer to the figure legend and surrounding text.
Chan et al. (Fri,) studied this question.