Iron deficiency in middle age associated with CHD, mortality
Among middle-aged individuals in Europe, absolute and functional iron deficiency were associated with incident CHD, and functional iron deficiency was linked to elevated risk for mortality, researchers reported.
“Absolute iron deficiency is the traditional way of assessing iron status, but it misses circulating iron,” Benedikt Schrage, MD, from the department of cardiology at the University Heart and Vascular Center and the German Center for Cardiovascular Research, Hamburg, Germany, said in a press release. “The functional definition is more accurate as it includes both measures and picks up those with sufficient stores but not enough in circulation for the body to work properly.”
Researchers assessed 12,164 individuals (median age, 59 years; 45% men) from three European population-based cohorts. Absolute iron deficiency was defined as ferritin of less than 100 g/L and severe absolute iron deficiency was defined as ferritin less than 30 g/L. Functional iron deficiency was defined as ferritin less than 100 g/L or ferritin 100 g/L to 299 g/L and transferrin saturation of less than 20%.
In the cohort, absolute iron deficiency was prevalent among 60% of individuals, severe iron deficiency was prevalent among 16.4% and functional iron deficiency was prevalent among 64.3%. During a median follow-up of 13.3 years, 18.2% of individuals died, with 4.7% attributable to a CV cause.
After adjusting for various confounders, absolute iron deficiency was not associated with all-cause (HR = 1.08; 95% CI, 0.98-1.19; P = .12) or CV mortality (HR = 1.22; 95% CI, 1-1.48; P = .05) but was associated with CHD development (HR = 1.2; 95% CI, 1.03-1.39; P = .01). In addition, there was no association between severe absolute iron deficiency and CV mortality (HR = 1.01; 95% CI, 0.76-1.34; P = .95), CHD development (HR = 1.22; 95% CI, 1-1.5; P = .05) or incident stroke (HR = 1.1; 95% CI, 0.87-1.4; P = .42), but there was an association with all-cause mortality (HR = 1.28; 95% CI, 1.12-1.46; P < .001).
Functional iron deficiency was associated with CHD development (HR = 1.24; 95% CI, 1.07-1.43; P < .01), CV mortality (HR = 1.26; 95% CI, 1.03-1.54; P = .03) and all-cause mortality (HR = 1.12; 95% CI, 1.01-1.24; P = .03). However, incident stroke was not associated with functional iron deficiency (HR = 1.15; 95% CI, 0.97-1.36; P = .12).
In the overall cohort, 5.4% of all deaths, 11.7% of CV-related deaths and 10.7% of CHD events were attributable to functional iron deficiency.
According to Schrage, it is important for future research to examine these associations in younger and non-European cohorts.
“If the relationships are confirmed, the next step would be a randomized trial investigating the effect of treating iron deficiency in the general population,” Schrage said.