Lifetime prevalence of exostoses in New Zealand surfers

Introduction: External auditory exostosis (EAE) is a benign, irreversible bony outgrowth that arises from the temporal bone. EAE projects into the external ear canal, potentially causing recurrent otitis externa and conductive hearing loss. Aim: To determine lifetime prevalence of EAE in New Zealand (NZ) surfers. Methods: This study used an online national survey. Results: Respondents were 1376 NZ surfers (recreational = 868, competitive = 508). Mean surfing experience was 16.2 years. Most self-classified as advanced surfers (36.5%), followed by intermediate (30.2%), expert (20.1%) and beginner (13.2%). Surfers reported an average of 214.2 h surfing (28.6% during winter) for the previous year. Overall lifetime prevalence of EAE was 28.9% (32.1% male, 14.6% female; P < 0.001), with the highest proportion of EAE was observed bilaterally (21.3%). Competitive surfers reported a significantly (P < 0.001) higher lifetime prevalence of EAE than recreational surfers (45.3% vs. 19.2%). A significantly higher (P < 0.001) lifetime prevalence of EAE was identified as skill level increased (7.1% in beginners to 55.6% in experts) and a two-fold increase (P < 0.001) of EAE in the highest (vs. lowest) quartile of surfing exposure. Neither winter surfing exposure nor which Island surfed were associated with EAE prevalence. Discussion: Although not as prevalent as in previous NZ research using otologic examinations, this study indicated that almost one-third of NZ surfers reported having had a diagnosis of EAE. Regular general practitioner otologic assessment and advice on appropriate prevention strategies for patients who surf may help prevent large lesions, recurrent ear infections and progressive hearing loss.