Association between postzoster neuralgia and tinnitus: A retrospective population-based cohort study

Tinnitus, characterized by the perception of sound without external stimuli, has not been extensively studied in relation to postzoster neuralgia (PZN) using large-scale, real-world data. This study aimed to explore the potential correlation between tinnitus and PZN. This study utilized data from the National Health Insurance Service - National Sample Cohort, a nationwide population-based database. The PZN group was selected from a cohort of 1 million individuals randomly extracted from the National Health Insurance Service - National Sample Cohort database. A non-PZN group was obtained through propensity score matching, taking several variables into consideration. The primary endpoint was the diagnosis of tinnitus. The PZN group comprised 3417 individuals, with an equal number of individuals in the non-PZN (control) group. The overall hazard ratio (HR) for tinnitus in the PZN group was 1.35 (95% confidence interval [CI]: 1.18-1.55). Subgroup analysis showed an adjusted HR of 0.77 (95% CI: 0.67-0.9) for tinnitus in males, 1.99 (95% CI: 1.53-2.59) in the middle-aged group (40-59 years), and 2.37 (95% CI: 1.83-3.08) in the older age group (≥60 years). Additionally, the adjusted HRs for developing tinnitus were higher in patients with comorbidities, including anxiety (1.46 [95% CI, 1.18-1.82]), hearing loss (3.34 [95% CI, 2.56-4.36]), and sleep disorders (1.48 [95% CI, 1.14-1.949]). Long-term follow-up revealed that the incidence of tinnitus was 1.35 times higher in the PZN group compared to the control group. Moreover, older age, female sex, anxiety, hearing loss, and sleep disorders were identified as factors that increase the risk of developing tinnitus.