Functional significance of early-life iron deficiency: outcomes at 25 years

Abstract

Objective: To evaluate adulthood function following chronic iron deficiency in infancy.

Study design: At 25 years, we compared 33 subjects with chronic iron deficiency in infancy to 89 who were iron-sufficient before and/or after iron therapy. Outcomes included education, employment, marital status, and physical and mental health.

Results: Adjusting for sex and socioeconomic status, a higher proportion of the group with chronic iron deficiency did not complete secondary school (58.1% vs 19.8% in iron-sufficient group; Wald value = 8.74; P = .003), were not pursuing further education/training (76.1% vs 31.5%; Wald value = 3.01; P = .08; suggestive trend), and were single (83.9% vs 23.7%, Wald value = 4.49; P = .03). They reported poorer emotional health and more negative emotions and feelings of dissociation/detachment. Results were similar in secondary analyses comparing the chronic iron-deficient group with subjects in the iron-sufficient group who had been iron-deficient before treatment in infancy. Path analysis showed direct paths for chronic iron deficiency in infancy and being single and more detachment/dissociation at 25 years. There were indirect paths for chronic iron deficiency and not completing secondary school via poorer cognitive functioning in early adolescence and more negative emotions via behavior problems in adolescence, indicating a cascade of adverse outcomes.

Conclusion: The observational nature of this study limits our ability to draw causal inference, even when controlling for background factors. Nonetheless, our results indicate substantial loss of human potential. There may be broader societal implications, considering that many adults worldwide had chronic iron deficiency in infancy. Iron deficiency can be prevented or treated before it becomes chronic or severe.

Keywords: HB; Hemoglobin; SES; Socioeconomic status.

Figure 1

Path analyses for not completing secondary school and being single. Goodness of fit under the Bayesian modeling was assessed by the Posterior Predictive P-value (PPP); values close to 0.5 in either direction are considered to indicate a good fit, whereas values less than 0.10 or greater than 0.90 indicate a poor fit. The path coefficients are provided for all statistically significant or suggestive paths. The strongest paths are shown as thick lines, other significant ones as regular lines, and those with suggestive trends as dashed lines. Statistical significance of individuals paths is indicated by * p < .05, ** p < .01, and † p < .10.

Figure 2

Path analyses for mental health outcomes (negative emotions, feelings of detachment/dissociation). Goodness of fit under the Bayesian modeling was assessed by the Posterior Predictive P-value (PPP); values close to 0.5 in either direction are considered to indicate a good fit, , whereas values less than 0.10 or greater than 0.90 indicate a poor fit. The path coefficients are provided for all statistically significant or suggestive paths. The strongest paths are shown as thick lines, other significant ones as regular lines, and those with suggestive trends as dashed lines. Statistical significance of individuals paths isare indicated by * p < .05, ** p < .01, and † p < .10.