Markers of Iron Metabolism and Stroke Risk: Cross-Sectional and Longitudinal Findings from the China Health and Nutrition Survey (CHNS)

Background: The association of iron metabolism or status with the stroke risk remains unclear. We aimed to examine the associations between markers of iron metabolism or status and stroke risk using data from the China Health and Nutrition Survey (CHNS). Methods: Overall, 8589 in the CHNS in 2009, and 7290 participants between 2009 and 2015 were included in the cross-sectional and longitudinal analyses, respectively. Markers included hemoglobin, ferritin (FET), transferrin (TRF), soluble transferrin receptor (sTRF-R), and ratio of sTRF-R/log FET (sTfR-F index). Multivariable logistic regression and Cox proportional hazards models were used to analyze the associations between those markers and risk of stroke. Age, gender, high-sensitivity CRP (hsCRP), body mass index (BMI), current smoking, drinking status, diabetes and hypertension were included as potential confounding factors. Results: We observed longitudinal associations of hemoglobin (HR: 1.54, 95% CI: 1.15 – 2.06, P = 0.004), and sTfR-F index (HR: 0.68, 95% CI: 0.46 – 0.99, P = 0.044) with stroke risk among the participants whose BMI ≤ 23 kg/m2. In addition, FET levels were significantly associated with stroke risk among female (HR: 1.45, 95% CI: 1.00 – 2.09, P = 0.049) after a median of 6.1 years follow-up. Hemoglobin, FET, TRF, sTRF-R, and sTfR-F index were not associated with the risk of stroke in overall analyses. Conclusion: FET among female, hemoglobin and sTfR-F index among those BMI ≤ 23 kg/m2 may be contributing factors for stroke.