Objective: To explore the recurrence rate of idiopathic sudden sensorineural hearing loss (ISSNHL). Design: Using the Taiwan Longitudinal Health Insurance Database, we compared in a retrospective cohort study 45,715 patients with ISSNHL between January 2001 and December 2006 with 45,715 age-, gender-, and comorbidity-matched controls without ISSNHL. We followed each patient from 180 days after the initial diagnosis until the end of 2009 and evaluated the incidence of ISSNHL for 3 years minimum. Results: The cumulative incidence of ISSNHL recurrence was 4.99%. Cox proportional hazard regressions showed that the 50-to 64-year-old age group had a higher adjusted hazard ratio (1.59; 95% confidence interval: 1.40-1.81) than did the 0- to 34-year-old age group. Different comorbidities did not significantly affect the incidence of ISSNHL relapse. Conclusions: The risk of an ISSNHL relapse in patients with a history of ISSNHL was higher than was the risk of a first occurrence of ISSNHL in the Controls. We suggest that physicians counsel patients with a history of ISSNHL to seek medical attention if they have hearing impairments because they may also have a high risk of an ISSNHL relapse. Evidence Level: 2B
