Ferritin-Based Definitions of Iron Deficiency and their Associations with Cardiovascular Disease in Women — National Health and Nutrition Examination Survey, United States, 2003-2018
Abstract
Ferritin-Based Definitions of Iron Deficiency and their Associations with Cardiovascular Disease-mortality in Women – NHANES 2003-2018
Domonique L. Hargrave, MED Jefferds, LP Hendrickson, OY Addo
Background: Iron deficiency (ID) is a major global public health concern, especially among women, and can vary by sociodemographic characteristics. Serum ferritin (SF) measures iron stores. Recently derived physiological SF thresholds (<25 µg/L for women aged <50 years and <33 µg/L for women aged >50 years) identify early treatable ID erythropoiesis. ID is a risk factor for developing cardiovascular disease, and literature suggests ID may be associated with cardiovascular disease (CVD). Our objective was to examine associations between physiological SF thresholds and the risk of CVD in women.
Methods: We conducted longitudinal analyses using National Health and Nutrition Examination Survey (NHANES) data, with linked National Death Index data. We included (N=13,170) non-pregnant women aged ≥20 years who had complete SF and CVD-mortality data, with a mean follow-up time of 8.8 years. We examined associations between ID (physiological SF thresholds) and CVD-mortality using adjusted Cox proportional-hazard models (HRs, 95% Confidence Intervals (CIs). Models were adjusted for age, race/ethnicity, education, and income. Analyses accounted for the complex survey design effects.
Results: The average age of women at baseline was 48.4 years. ID prevalence was 20.2%. There were 1,525 cases of CVD-mortality per 130,684 person-years follow-up. Physiologic ID was associated with CVD-mortality in unadjusted analyses. This association with CVD-mortality was not significant after adjustment for age and sociodemographic factors (aHR: 1.22, 95% CI 0.81-1.86).
Conclusions: Physiological ID thresholds did not predict risk of CVD-mortality in this sample when adjusting for age and sociodemographic factors. Whether screening with non-physiological thresholds might identify individuals with higher risk of CVD-mortality merits further attention.