Prevalence of hearing loss across age groups in Nepal: a systematic review and meta-analysis protocol

Hearing loss is a global health problem. It is not only an impairment of hearing but also has debilitating effects on the social, emotional and cognitive domains. It also imposes costs on a country's healthcare sector, which must first be identified to prevent the prevalence of the impairment. In a low- and middle-income country like Nepal, there is no published systematic review on the prevalence of hearing loss. We aim to perform a systematic review and meta-analysis on the national prevalence of hearing loss in Nepal across all age groups.

We will report our findings in line with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines. We will search the MEDLINE (PubMed) and Nepal Journals Online databases for publications in Nepali and English. Google Scholar will also be used to broaden the search scope. We will also search grey literature, like government reports. Studies that report the prevalence of hearing loss in Nepal will be included. Titles and abstracts of the studies will be independently screened by both reviewers (PB and SA) using Rayyan software. Full-text articles that pass the initial screening will also be independently reviewed by both reviewers. Disagreements will be resolved through discussion at all stages. If necessary, a third reviewer will be invited, and the original author will be contacted where appropriate (e.g., when data are missing in the original study). We will perform a narrative synthesis of the study results. Cochran's Q test and the I² statistic will be calculated to assess heterogeneity. I² values of 25%, 50% and 75% will be interpreted as indicating low, moderate and high heterogeneity, respectively. We will conduct a meta-analysis using a random-effects model, which accounts for both within-study and between-study variability. We will perform a sensitivity analysis to examine whether a single study disproportionately contributes to heterogeneity. Potential publication bias will be evaluated using both visual and statistical approaches (Funnel plot and Egger's test). In addition, if funnel plot asymmetry is observed, trim-and-fill analysis will be conducted. Statistical tests will be performed in R (V.4.3.1) using RStudio (V.2023.06.1+524) with the metafor package for meta-analysis.

Ethics approval is not required for this protocol. This review and meta-analysis are based entirely on secondary data; no primary data will be collected. Our findings will be useful to quantify the national prevalence of hearing impairment in Nepal. They may be useful for developing intervention policies and furthering research agendas for government agencies and hearing-health researchers alike. The results will be presented at conferences, published in peer-reviewed journals and shared with relevant policy-making bodies.

CRD420251120903.