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Iron deficiency anemia appears linked to hearing loss in adults
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Iron deficiency anemia appeared associated with greater likelihood of hearing loss in adults, according to a retrospective cohort study.
“The role of iron in the vasculature and nervous system raises the possibility of its association with other common types of adult hearing loss beyond sudden sensorineural hearing loss,” Kathleen M. Schieffer, BS, from the division of colon and rectal surgery in the department of Surgery at Pennsylvania State University College of Medicine, and colleagues wrote.
“Because iron deficiency anemia is a common and reversible condition, further understanding of the association between iron deficiency anemia and all types of hearing loss in a population of U.S. adults may open new possibilities for treatment.”
The researchers identified 305,339 individuals aged 21 to 90 years (mean age, 50.1 years; men, 43.4%) using electronic medical records from the Penn State Milton S. Hershey Medical Center to examine the association between iron deficiency anemia and sudden sensorineural hearing loss, conductive hearing loss and combined hearing loss.
Iron deficiency anemia occurred in 0.7% of patients and combined hearing loss — defined as any combination of conductive hearing loss — occurred in 1.6% of the cohort.
Sudden sensorineural hearing loss (1.1%; P = .005) and conductive hearing loss (3.4%; P < .001) demonstrated a significant association with iron deficiency anemia.
Logistic regression analysis adjusted for sex confirmed the association between iron deficiency anemia and greater odds for combined hearing loss (adjusted OR = 2.41; 95% CI, 1.9-3.01) and sudden sensorineural hearing loss (adjusted OR = 1.82; 95%CI, 1.18-2.66).
Schieffer and colleagues noted additional studies are warranted to determine whether there is a link between iron supplementation and hearing status.
“An association exists between iron deficiency anemia in adults and hearing loss,” researchers wrote. “The next steps are to better understand this correlation and whether promptly diagnosing and treating iron deficiency anemia may positively affect the overall health status of adults with hearing loss.” – by Kristie L. Kahl
Disclosure: The researchers reported no relevant financial disclosures.
Perspective
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I reviewed this study with one of our statisticians because you have to be careful whenever you have an epidemiological study that is trying to show an association between two different entities.
There are methodologic problems with the way this study has compiled the data. For example, it is a single-institution study, yet, something like this should be examined throughout many centers. The second concern is that the researchers use ICD9 coding as their way of finding their study subjects. There are problems with using ICD9 codes for this purpose, because sometimes patients are labeled with a code, yet they do not necessarily have that problem. You have to dig down a little deeper to see if these patients truly have the problem that the ICD9 code states that they have.
In addition, the researchers discuss the differences in combined hearing loss between men and women, which showed a significant difference at P < .001 (included in Table 1 of the study), but the absolute differences are very small at 0.3% vs. 0.1%. I believe that blaming iron deficiency anemia for hearing loss based on these numbers is a bit of a stretch.
Ideally, research would involve taking patients who are clearly iron deficient, measuring their hearing, then treating them and measuring their hearing again. Or, take patients who are not iron deficient that become iron deficient, and check their hearing before and after. In these methods, the patients themselves serve as controls. I recommend against making such connections with this kind of epidemiologic study.
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