Association between vitamin D and ear disease: a meta-analysis and systematic review

Abstract
Background
Vitamin D deficiency is a suggested cause and risk factor for various ear diseases. This review assessed the role of vitamin D in ear diseases such as otitis media (OM); this study aimed to assess potential relationships between serum vitamin D level and OM risk; and determined the usefulness of vitamin D supplementation for ear disease prevention and treatment.

Material and methods
This systematic review searched the PubMed, EMBASE, Google Scholar, Web of Science, and the Cochrane Database for studies on vitamin D deficiency as a risk factor for ear diseases. A total of 55 articles were screened based on their titles. The abstracts were then reviewed to identify the 11 articles analyzed in the present study.

Results
Statistical heterogeneity was observed among the 11 studies for subgroup analysis of plasma vitamin D level according to disease type (acute otitis media [AOM], P < 0.00001; chronic otitis media [COM], P = 0.00001) and age (≤ 5 years, P < 0.00001; > 5 years, P < 0.00001). Heterogeneity was also observed in the frequency of participants with sufficient plasma vitamin D levels according to disease type (AOM, P < 0.00001; COM, P = 0.00001) and age (≤ 5 years, P < 0.00001; > 5 years, P = 0.003; I2 = 70%: substantial heterogeneity).

Conclusion
Vitamin D deficiency is common in otolaryngology patients, for which supplementation showed promising results. Vitamin D deficiency was associated with the etiopathology of ear diseases in adults and children. We recommend empirical supplementation of vitamin D in otolaryngology patients and further studies investigating this supplementation.