Prevalence and causes of hearing impairment in Fundong Health District, North West Cameroon Short title: Hearing impairment in Cameroon

Objective: To estimate the prevalence and causes of hearing impairment in Fundong Health District, North West Cameroon. Methods: We selected 51 clusters of 80 people through probability proportionate to size sampling. Initial hearing screening was undertaken through an otoacoustic emission (OAE) test. Participants aged 4+ years who failed this test in both ears or for whom an OAE reading could not be taken underwent a manual pure-tone audiometry (PTA) screening. Cases of hearing impairment were defined as those with pure-tone average ≥41 dBHL in adults and ≥35 dBHL in children in the better ear, or children under age 4 who failed the OAE test in both ears. Each case with hearing loss was examined by an ear, nose and throat nurse who indicated the main likely cause. Results: We examined 3,567 (86.9%) of 4,104 eligible people. The overall prevalence of hearing impairment was 3.6% (95% confidence interval (CI): 2.8–4.6). The prevalence was low in people aged 0–17 (1.1%, 0.7– 1.8%) and 18–49 (1.1%, 0.5–2.6%) and then rose sharply in people aged 50+ (14.8%, 11.7–19.1%). Among cases, the majority were classified as moderate (76%), followed by severe (15%) and profound (9%). More than one third of cases of hearing impairment were classified as unknown (37%) or conductive (37%) causes, while sensorineural causes were less common (26%). Conclusions: Prevalence of hearing impairment is in line with WHO estimate for Sub-Saharan Africa. The majority of cases with known causes are treatable, with impacted wax playing a major role.