Increased risk of cholesteatoma among patients with allergic rhinitis: A nationwide investigation.

OBJECTIVES: No large population-based studies have reported on the risk of cholesteatoma developing after allergic rhinitis (AR). This study used a nationwide population-based claims database to investigate the hypothesis that AR may increase the risk of cholesteatoma. STUDY DESIGN: Retrospective cohort study. METHODS: Data from Taiwan's Longitudinal Health Insurance Database were analyzed to compile the following: 1) 15,953 patients newly diagnosed with AR between 1997 and 2000, and 2) a comparison cohort of 63,812 matched non-AR enrollees (with a ratio of 1 to 4). Each patient was followed for 10 years to identify cases in which cholesteatoma subsequently developed. The Kaplan-Meier method was used to determine the cholesteatoma-free survival rate, and the log-rank test was used to compare survival curves. Cox proportional hazard regressions were performed to compute adjusted hazard ratios (HRs). RESULTS: Among the 79,765 patients enrolled in this study, 45 (159,364 person-years) from the AR cohort and 88 (638,130 person-years) from the comparison cohort were diagnosed with cholesteatoma during the follow-up period (incidence rates 0.28 and 0.14 of 1,000 person-years, respectively). Patients with AR were more likely to develop cholesteatoma compared to those without AR (adjusted HR 1.57, 95% confidence interval = 1.05-2.34, P < 0.05). Patients with AR presented a significantly lower 10-year cholesteatoma-free survival rate than did those in the comparison group (log-rank, P < 0.001). CONCLUSION: This is the first study to demonstrate a link between AR and the development of cholesteatoma. We suggest that clinicians keep this association in mind and carefully investigate the possibility of development of cholesteatoma among patients with AR. LEVEL OF EVIDENCE: 3b. Laryngoscope, 128:547-553, 2018.