Red Blood Cell Distribution Width to Albumin Level Ratio Linked to Mortality Risk: JAMA Study Finds

In the cohort study involving 469 572 participants at baseline and 44 383 deaths during follow-up periods, higher red blood cell distribution width to albumin concentration (RAR) levels ratio were associated with increased risks of all-cause and cause-specific mortality.

"These findings suggest that the RAR, assessed via routine laboratory tests, could be a promising indicator that is reliable, inexpensive, and simple for identifying individuals at high mortality risk in clinical practice," the researchers wrote.

Red blood cell distribution width measures the variation in the size of red blood cells. At the same time, albumin is a protein produced by the liver that plays a crucial role in maintaining blood volume and regulating various physiological processes. RDW and albumin levels are routinely measured in clinical practice as part of routine blood tests, offering valuable insights into a patient's health status.

The ratio of red blood cell distribution width (RDW) to albumin concentration (RAR) has emerged as a reliable prognostic marker for mortality in patients with several diseases. However, there is no information on whether RAR is associated with mortality in the general population. To fill this knowledge gap, Meng Hao, Fudan University Pudong Medical Center, Shanghai, China, and colleagues aimed to explore whether RAR is associated with all-cause and cause-specific mortality and to elucidate their dose-response association.

For this purpose, the researchers conducted a population-based prospective cohort study using data from participants in the 1998-2018 US National Health and Nutrition Examination Survey (NHANES) and from the UK Biobank with baseline information from 2006 to 2010. It included participants with complete data on serum albumin concentration, RDW, and cause of death. The NHANES data were linked to the National Death Index records through December 31, 2019. Causes and dates of death were obtained from the National Health Service Central Register Scotland (Scotland) and National Health Service Information Centre (England and Wales), for the UK Biobank.

Cox proportional hazards regression models evaluated the potential associations between RAR and all-cause and cause-specific mortality risk. Restricted cubic spline regressions were applied to estimate possible nonlinear associations.

The researchers reported the following findings:

• In NHANES, 50 622 participants 18 years of age or older years were included (mean age, 48.6 years; 51.6% female), and their mean RAR was 3.15.
• In the UK Biobank, 418 950 participants 37 years of age or older (mean, 56.6 years; 53.7% female) were included, and their mean RAR was 2.99.
• The NHANES documented 7590 deaths over a median follow-up of 9.4 years, and the UK Biobank documented 36 793 deaths over a median follow-up of 13.8 years.
• According to the multivariate analysis, elevated RAR associated significantly with greater all-cause mortality risk (NHANES: hazard ratio [HR], 1.83; UK Biobank: HR, 2.08), as well as mortality due to malignant neoplasm (NHANES: HR, 1.89; UK Biobank: HR, 1.93), heart disease (NHANES: HR, 1.88; UK Biobank: HR, 2.42), cerebrovascular disease (NHANES: HR, 1.35; UK Biobank: HR, 2.15), respiratory disease (NHANES: HR, 1.99; UK Biobank: HR, 2.96), diabetes (NHANES: HR, 1.55; UK Biobank: HR, 2.83), and other causes of mortality (NHANES: HR, 1.97; UK Biobank: HR, 2.40) in both cohorts.
• The researchers found a nonlinear association between RAR levels and all-cause mortality in both cohorts.

The findings suggest that RAR may be a reliable, simple, and inexpensive indicator for identifying individuals at high mortality risk in clinical practice.

As the scientific community continues to explore the implications of these findings, the study represents a significant step forward in understanding the complex interplay between hematological parameters and mortality outcomes. Researchers aim to improve patient care and outcomes across diverse clinical settings by uncovering new insights into predictive biomarkers.

Reference:

Hao M, Jiang S, Tang J, et al. Ratio of Red Blood Cell Distribution Width to Albumin Level and Risk of Mortality. JAMA Netw Open. 2024;7(5):e2413213. doi:10.1001/jamanetworkopen.2024.13213