# The non-linear association between serum iron and severe impairment of activities of daily living in ischemic stroke patients

## TL;DR

This study finds a non-linear link between serum iron levels and severe daily living impairment in stroke patients, with a threshold at 17.5 μmol/L.

## Contribution

The novel finding is a non-linear association with a specific threshold for serum iron impacting stroke patient recovery.

## Key findings

- A non-linear relationship exists between serum iron and severe ADL impairment (p = 0.005).
- Each 1 μmol/L increase in serum iron below 17.5 μmol/L reduces severe ADL impairment odds by 9%.
- No significant association is observed above the 17.5 μmol/L threshold.

## Abstract

This study aims to explore the dose–response relationship and threshold effect of serum iron levels on severe impairment of activities of daily living (ADL) in ischemic stroke patients.

This cross-sectional study included 2,035 ischemic stroke patients admitted to Shanghai East Hospital from 2020 to 2022. Serum iron levels were measured upon admission, and ADL was evaluated using the Barthel Index. Restricted cubic spline regression, multivariate logistic models, and subgroup analysis were employed to analyze the dose–response relationship.

A non-linear relationship (p = 0.005) was observed between serum iron and severe ADL impairment, with an inflection point at 17.5 μmol/L. Below this threshold, each 1 μmol/L increase in serum iron was associated with 9% lower odds of severe ADL impairment (OR = 0.91, 95% CI: 0.876–0.946). No significant association was observed above 17.5 μmol/L (p > 0.05). Subgroup analyses revealed no significant interactions in any subgroup.

The study found a non-linear relationship between serum iron and severe ADL impairment after ischemic stroke, with an inflection point at about 17.5 μmol/L. Future prospective studies are necessary to clarify this association.