The Incidence of Sensorineural Hearing Loss Diagnoses in People with and without Parkinson's Disease.

BACKGROUND: Parkinson's disease (PD) and sensorineural hearing loss (SNHL) are both prevalent conditions among older adults. Although increasing number of studies have investigated SNHL as a risk factor for PD, it is not well known how diagnosed PD affects the likelihood of SNHL diagnosis. OBJECTIVES: To evaluate the temporal changes in the amount of SNHL diagnoses in relation to PD diagnosis. METHODS: This nationwide register-based study included 22,189 community-dwelling persons who received a clinically verified PD diagnosis in 1996-2015 in Finland and a 1:1 matched comparison cohort. PD diagnoses were identified from the Special Reimbursement Register and SNHL diagnoses were extracted from Care Register for Healthcare. Incidences of the diagnoses were calculated per 100 person-years (PY) for each six-month period from ten years before to ten years after PD diagnosis. RESULTS: Before PD diagnosis the incidence of SNHL diagnosis was higher among people with PD (0.65/100 PY) than in the comparison cohort (0.58/100 PY, hazard ratio, 95% CI 1.11, 1.05-1.18) and increased similarly in both groups. After PD diagnosis the incidence was lower among people with PD (1.00 and 1.28/100 PY, hazard ratio, 95% Cl 0.78, 0.74-0.83) and declined shortly after PD diagnosis whereas it continued to increase in the comparison group. CONCLUSIONS: After PD diagnosis, the incidence of SNHL appears to decline compared to the control group, suggesting a possible deprioritization of hearing care. Our findings are also consistent with previous research showing an association between SNHL and PD, with a higher incidence of SNHL observed in individuals with PD.