Association of Sensorineural Hearing Loss in Patients With Alopecia Areata: A Nationwide Population-Based Cohort Study

Alopecia areata (AA) is a common autoimmune disease, leading to chronic and relapsing hair loss.¹ Current evidence suggests that follicular melanocytes may be an important target in the autoimmune process of AA.² In addition to their presence in the skin, melanocytes are also present as intermediate cells in the stria vascularis of the cochlea, which are critical for normal hearing. In patients with Vogt-Koyanagi-Harada disease, a rare autoimmune disorder that targets melanocytes, sensorineural hearing loss (HL) is a common complication in late-stage disease. Few studies have found audiological abnormalities in patients with AA^3,4; however, existing studies are limited by their cross-sectional designs and small sample sizes. This nationwide population-based cohort study was conducted to investigate the risk of HL in patients with AA using claims data from the National Health Insurance Research Database in Taiwan.

This study was approved by the Institutional Review Board of Taipei Veterans General Hospital (2018-07-016AC). The institutional review board waived the requirement to obtain informed consent owing to the use of deidentified data (VGHIRB No.: 2018-07-016AC). We identified patients with AA diagnosed by dermatologists between January 1, 1998, and December 31, 2011. The diagnosis of AA was established according to the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 704.01. For each patient with AA, 10 controls were selected after matching for age, sex, monthly premium, and residence. The primary outcome assessed was new-onset HL, which was identified by ICD-9-CM code 389. The diagnosis of HL was established by otorhinolaryngologists and was classified into conductive HL (ICD-9-CM code 389.0), sensorineural HL (ICD-9-CM code 389.1), mixed HL (ICD-9-CM code 389.2), and others (ICD-9-CM codes 389.7, 389.8, and 389.9). Participants were observed until a diagnosis of HL, death, or December 31, 2013. Cox regression model was used to calculate adjusted hazard ratios with 95% CIs. Two-sided P values <.05 were considered statistically significant. Data management and analyses were performed using the Statistical Analysis System (SAS) software, version 9.4 (SAS Institute).

This study included 5002 patients with AA and 50 020 controls (Table 1). Overall, 33 patients with AA developed HL, with an overall rate of 77.46 cases per 100 000 person-years, whereas 75 individuals without AA had HL, with an overall rate of 17.53 cases per 100 000 person-years. After adjustment for potential confounders, patients with AA had a higher risk of developing HL (adjusted hazard ratio, 4.18; 95% CI, 2.78-6.31) than controls (Table 2). According to the type of HL, patients with AA had significantly increased risk of developing conductive HL, sensorineural HL, and other types of HL.

In this large cohort, we found an association of sensorineural HL in patients with AA. In addition, we observed an association between AA and conductive HL. However, these findings should be interpreted cautiously considering the small numbers of incident cases of conductive HL. Further studies with larger sample sizes are required to confirm our findings.

Alopecia areata is a T-cell–mediated autoimmune condition owing to the collapse of immune privilege in hair follicles. Some authors have proposed that follicular melanocytes are the main target in the autoimmune process.² Melanocytes of the inner ear protect the cochlea against various stresses, especially loud noise. Melanocytes are also essential for creating endolymphatic potential, which is important for cochlear hair cell function and normal hearing. Melanocyte destruction by autoimmune reactions may therefore lead to impaired auditory function.⁵ Aside from melanocytes, several inner ear antigens, including heat shock protein 70 and collagen type II, have been considered to play an important role in the pathogenesis of HL among various systemic autoimmune diseases.⁶ Future research is required to elucidate the exact mechanisms underlying the association between AA and risk of sensorineural HL.⁶

This study has some limitations. First, the incidence of AA might be underestimated because only those who sought consultation were included in the study. Second, the database we used lacks some important confounders, including genetic background and environmental noise exposure. Finally, most of the participants were Taiwanese; therefore, the generalizability of our findings remains uncertain.

In conclusion, AA is associated with increased risk of HL. Physicians should be aware of this potential association and consider audiology referrals as needed.

Accepted for Publication: May 19, 2020.

Corresponding Authors: Mu-Hong Chen, MD, PhD, Department of Psychiatry (kremer7119@gmail.com), and Ying-Xiu Dai, MD, Department of Dermatology (daiinxiu@gmail.com), Taipei Veterans General Hospital, No. 201, Sec. 2, Shipai Rd, Beitou District, Taipei City, Taiwan 11217, ROC.

Published Online: July 29, 2020. doi:10.1001/jamadermatol.2020.2430

Author Contributions: Dr M.-H. Chen had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Dai, Chang, T. Chen, M. Chen.

Acquisition, analysis, or interpretation of data: Ma, Tai, Dai, T. Chen, M. Chen.

Drafting of the manuscript: Ma, Dai, Chang, T. Chen, M. Chen.

Critical revision of the manuscript for important intellectual content: Ma, Tai, Dai, T. Chen, M. Chen.

Statistical analysis: Tai.

Administrative, technical, or material support: Ma, Chang.

Study supervision: Dai, T. Chen, M. Chen.

Conflict of Interest Disclosures: None reported.

Funding/Support: This study was funded by the Ministry of Science and Technology (MOST), R.O.C., under grant MOST 107-2314-B-075-032-MY3-2.

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.