Simple Blood Ratio Predicts Heart Failure Readmission Risk, Study Finds

Heart failure remains one of medicine’s most stubborn revolving doors: patients leave the hospital, only to return within months, sometimes weeks. Now a team of researchers in China reports that a remarkably simple calculation, drawn from two routine blood tests, may identify which patients are most likely to bounce back through the hospital doors. The finding, published in Frontiers in Cardiovascular Medicine, suggests that a single number, the red cell distribution width-to-albumin ratio, or RAR, could give clinicians an early warning system for the vulnerable months after discharge.

The study drew on the Zigong Heart Failure Database, a collection of electronic medical records from 2,008 patients hospitalized with heart failure at Zigong Fourth People’s Hospital between December 2016 and June 2019. After excluding patients with missing laboratory values or incomplete readmission data, the researchers assembled a final cohort of 1,854 patients, most of them elderly, with 73.4 percent aged over 70 years. The team then divided the patients into four groups based on their RAR values and tracked whether they were readmitted to the hospital for any reason within six months of their index admission.

The results were striking. Overall, 38.5 percent of the patients, 714 of the 1,854, were readmitted within six months. But the risk was not evenly distributed. In unadjusted analyses, every one-unit increase in RAR was associated with a 57 percent higher risk of readmission, with a hazard ratio of 1.57 and a 95 percent confidence interval spanning 1.27 to 1.93. Even after the researchers adjusted for a long list of potential confounders, including age, sex, body mass index, cardiac function class, troponin and BNP levels, C-reactive protein, comorbidity burden, and the full range of heart failure medications, the association held firm, with a hazard ratio of 1.52.

When the researchers compared the highest RAR quartile with the lowest, the difference remained clear. Patients in the top quartile faced a 39 percent greater risk of six-month readmission than those in the bottom quartile, with a hazard ratio of 1.39 and a confidence interval of 1.10 to 1.76. Kaplan-Meier curves, which track cumulative readmission rates over time, showed that the high-RAR group diverged visibly from the low-RAR group, and a log-rank test confirmed the difference was statistically significant at P = 0.0025.

What makes RAR so informative is the biology behind its two components. Red cell distribution width, or RDW, measures the variability in the size of circulating red blood cells, a value routinely reported on every complete blood count. In recent years, RDW has emerged as a surprisingly powerful marker of chronic low-grade inflammation, and elevated RDW has been linked to more severe inflammation and to disorders of iron mobilization, in which iron is locked away in inflammatory stores rather than being available for red blood cell production. This iron sequestration can inhibit the maturation of red cells driven by erythropoietin, producing the anemia of chronic disease, a common companion of advanced heart failure.

Albumin, the second component, is the most abundant protein in human serum and a workhorse of physiology, with anti-inflammatory, antioxidant, anticoagulant, and antiplatelet properties. Serum albumin concentration is a well-established indicator of both nutritional status and inflammatory response, and low albumin levels in cardiovascular disease reflect the combined toll of chronic inflammation, malnutrition, and vascular leakage. By dividing RDW by albumin, RAR captures two dimensions of physiological dysfunction at once: the inflammatory and hematologic stress reflected in the numerator, and the nutritional and anti-inflammatory reserve reflected in the denominator. The researchers argue that this composite signal may carry more predictive weight than either measurement alone.

The association proved remarkably robust across the population. Subgroup analyses stratified by sex, age below or above 70 years, body mass index, New York Heart Association functional class, and the use of medications including diuretics, beta-blockers, ACE inhibitors or ARBs, statins, and inotropic agents all showed consistent results, with no statistically significant interactions. In other words, the link between RAR and readmission was not driven by any particular patient profile or treatment pattern, strengthening the case that RAR functions as an independent predictor.

The findings fit into a growing body of evidence on RAR as a prognostic marker. Previous studies have linked elevated RAR to mortality in patients with heart failure, acute myocardial infarction, atrial fibrillation, diabetes mellitus, and chronic kidney disease. Earlier work also found that higher RDW alone predicted three-month readmission in heart failure patients, while a related marker, the red cell distribution width-to-platelet ratio, showed no significant association with six-month readmission. The new study extends this literature by combining the two biomarkers into a single ratio, incorporating a broader set of confounders, and focusing on an East Asian population, a group that had been underrepresented in prior research.

The clinical appeal of RAR lies in its accessibility. Both RDW and albumin are measured on routine blood draws, costing essentially nothing beyond tests already performed on nearly every hospitalized patient. If validated in prospective studies, RAR could be calculated at the bedside within hours of admission, flagging patients who need closer follow-up, more aggressive medication optimization, or earlier post-discharge contact. With roughly one million heart failure admissions and readmissions occurring annually in the United States alone, and between 20 and 50 percent of discharged patients returning within a year, even modest improvements in risk stratification could translate into substantial savings and better outcomes.

The authors are careful to note the limits of their work. As a retrospective cohort study, the findings demonstrate correlation rather than causation. RAR was measured only once, at admission, so the study cannot capture how the ratio changes over time. Residual confounding cannot be excluded despite extensive statistical adjustment, and the database lacked detailed reasons for readmission, meaning the outcome reflects all-cause rehospitalization rather than heart failure-specific events. Still, the researchers conclude that RAR may serve as a simple, cost-effective predictor of readmission during the post-discharge vulnerability period, and they plan to investigate whether the marker is associated with the development of heart failure in broader populations. For now, the study adds a compelling entry to the search for cheap, reliable signals hidden in the most ordinary of laboratory tests.

Subject of Research: Association of the red cell distribution width/albumin ratio with 6-month readmission risk in heart failure patients

Article Title: Association of the red cell distribution width/albumin ratio with 6-month readmission risk in heart failure patients

Article References: Association of the red cell distribution width/albumin ratio with 6-month readmission risk in heart failure patients. (n.d.). https://doi.org/10.3389/fcvm.2026.1842863

Image Credits: AI Generated

DOI: 10.3389/fcvm.2026.1842863

Keywords: Association, cell, distribution, width, albumin, ratio, month, readmission, risk, heart, failure, patients