Prevalence, risk factors and knowledge of noise-induced hearing loss among metal fabricators in Mbarara city, Uganda: a cross-sectional study.

Background and objectives: Noise-induced hearing loss (NIHL) is a common permanent health condition and yet preventable. Individuals who work in noisy environments such as metal fabricators in the informal sector are at an especially high risk of developing NIHL. We set out to determine the prevalence, risk factors and knowledge about NIHL among metal fabricators in Mbarara City (Uganda). Methods: We conducted a descriptive cross-sectional study in Mbarara city among metal fabricators for a period of 6 months. 178 participants were recruited using a consecutive sampling method, data was collected using a data collection tool which captured their responses and examination findings, workshop noise levels were measured using a hand-held sound level meter and the hearing threshold by a pure tone audiometer. Then analysed the data using STATA V.15.0. Results: The majority were young (18-24 years) males (96.1%). The prevalence of NIHL was 19.7% and we noted this increased with advancing age and work experience in the metal fabrication industry. Only 23.2% of metal fabricators had adequate knowledge levels about NIHL. After adjusting for confounding, we found that only 'history of employment in a noisy environment' truly increased the odds (OR 3.3 95% CI 1.1 to 9.0 and a p value of 0.028) of developing NIHL in this population. Advancing age, having a 'relative with hearing loss', increasing work experience in metal fabrication (>1 year), a positive history of smoking and recent use of ototoxic drugs also demonstrated increased odds of association with NIHL, that is 3.4 (0.7-16.8, 0.132), 2.0 (0.8-5.1, 0.137), 9.9 (1.0-16.8, 0.055), 3.4 (0.5-24.2, 0.061) and 1.7 (0.6-4.9, 0.310) respectively, with their corresponding 95% CIs and p values, though these were not statistically significant. Conclusion: The prevalence of NIHL among metal fabricators in Mbarara city is low. Knowledge about NIHL was inadequate among most fabricators. NIHL prevalence increased with work experience, more so among those with a history of work in a noisy environment. Other contributory factors were advancing age, a family history of hearing loss, smoking and use of ototoxic drugs.