# Red cell distribution width-to-albumin ratio and hypertension risk: age-specific threshold effects identified in the 2017–2020 NHANES U.S. Adult population

## TL;DR

This study found that a blood test ratio called RAR is linked to higher hypertension risk, especially when it's above 3.4, and the effect is stronger in certain groups like diabetics.

## Contribution

The study identifies age-specific threshold effects of RAR on hypertension risk in a U.S. adult population.

## Key findings

- RAR showed a linear positive association with hypertension when RAR was ≥ 3.4.
- For adults aged 40–60 years, the inflection point was RAR = 3.92 with stronger associations below this threshold.
- Diabetics, females, and individuals over 40 showed stronger associations between RAR and hypertension.

## Abstract

As a major modifiable risk factor for cardiovascular diseases worldwide, hypertension novel biomarkers that integrate inflammatory and metabolic pathways may improve risk stratification. The association between the red cell distribution width-to-albumin ratio (RAR), a newly identified inflammatory biomarker, and hypertension has not been systematically evaluated in population-based studies.

A cross-sectional study included 7,878 adults. Weighted multivariable logistic regression and threshold effect models were employed to analyze nonlinear associations, with subgroup analyses exploring heterogeneity.

RAR showed a linear positive association with hypertension (adjusted OR = 1.26 per unit, 95%CI:1.09–1.44, P < 0.05), a threshold effect was observed. Piecewise regression revealed a significant association when RAR ≥ 3.4, with a higher hypertension prevalence (adjusted OR = 1.34, 95%CI:1.17–1.54), while no association existed below 3.4 (P = 0.408). For those aged 40–60 years, the inflection point was RAR = 3.92 (95%CI:3.76–4.51), with stronger associations observed below this threshold (OR = 1.80, 95%CI:1.33–2.43). Subgroup analyses revealed significant heterogeneity: diabetics exhibited stronger associations than non-diabetics (interaction P = 0.02), and enhanced associations were also observed in females and individuals aged > 40 years.

This study confirmed a linear positive correlation between red blood cell distribution width and albumin ratio (RAR) and the prevalence of hypertension, RAR ≥ 3.4 was associated with higher hypertension prevalence and may help identify high-risk subgroups, particularly among diabetics, but its predictive value warrants validation through prospective cohort studies.