Demographic predictors of major depressive disorder among patients with iron deficiency anemia: a retrospective cross-sectional observational study

Background Iron deficiency anemia (IDA) has been increasingly associated with neuropsychiatric conditions, including major depressive disorder (MDD). However, demographic variation in documented MDD diagnoses among patients with IDA remains underexplored in large clinical populations. Methods We conducted a retrospective cross-sectional observational study using de-identified electronic health records from 8,593 adult patients at the University of California, Irvine Medical Center (2017–2024). IDA was identified using ICD-10-CM codes, and MDD was classified as single-episode or recurrent. Multivariate logistic regression adjusted for age, sex, race, and ethnicity was used to assess demographic variation in MDD diagnoses among patients with IDA. Results Among 8,593 patients with IDA, single-episode MDD was present in 23.2% and recurrent MDD in 7.2%. Female patients demonstrated significantly higher odds of single-episode MDD (OR 1.52, 95% CI 1.35–1.72) and recurrent MDD (OR 1.84, 95% CI 1.50–2.28) compared with males. Adults ≥ 55 years demonstrated increased odds of single-episode MDD (OR 1.62, 95% CI 1.27–2.08 and OR 1.40, 95% CI 1.12–1.76, respectively), with no significant association observed for recurrent MDD. Asian individuals had significantly lower odds of single-episode (OR 0.44, 95% CI 0.37–0.52) and recurrent MDD (OR 0.39, 95% CI 0.28–0.52) than White patients. Conclusion This large cross-sectional study identified significant demographic variation in documented MDD diagnoses among patients with IDA. These findings help characterize patterns of psychiatric comorbidity within IDA populations and motivate future longitudinal studies examining the relationship between IDA and depressive disorders.