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Published on: January 19, 2024
Red blood cell distribution width and all-cause mortality in low-income populations: a NHANES-based cohort study
Hui Ma1, Yu-Han Li2, Jin-Da Zhao3
1Department of Laboratory Medicine, Fifth People's Hospital of Kunshan, Suzhou, China.
Background:
Red blood cell distribution width (RDW) may be associated with all-cause mortality. This study aimed to evaluate the relationship between RDW and all-cause mortality in low-income populations. Low-income status was defined as a Family Income to Poverty Ratio (PIR) < 1, consistent with previous studies. All analyses were weighted to account for the complex sampling design.
Methods:
This study included 92,062 adults from the National Health and Nutrition Examination Survey (NHANES) 1999-2016 database, with survival follow-up through December 31, 2016. Analyses were restricted to the low-income subgroup and weighted according to the NHANES sampling design to ensure national representativeness. Linear and nonlinear multivariable Cox regression models were used to evaluate the association between RDW and all-cause mortality. Participants with missing data were excluded through complete-case analysis. Statistical analyses were performed using EmpowerStats and R software.
Results:
A total of 17,412 participants were included in the final analysis. In the low-income population, RDW showed a nonlinear association with all-cause mortality, characterized by a threshold at 15.9%. Below this threshold, each 1% increase in RDW was associated with a 29% higher risk of mortality (HR = 1.29, 95% CI: 1.20-1.38, P < 0.0001), while above 15.9%, the association was no longer statistically significant. Multivariable Cox regression analysis demonstrated that RDW remained significantly associated with mortality after adjustment for potential confounding factors (hazard ratio [HR] = 1.11, 95% confidence interval [CI]: 1.08-1.15, P < 0.0001). Specifically, each 1% increase in RDW was associated with an 11% increase in the risk of all-cause mortality.
Conclusion:
Elevated RDW was associated with increased all-cause mortality among low-income adults and may indicate a potential prognostic marker for mortality risk in this vulnerable population. However, further studies are needed to validate its clinical predictive utility.