Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. An estimated 1.57 billion people (one-in-five individuals) globally had hearing loss in 2019.

2. By 2050, 2.45 billion people are expected to have hearing loss, representing a 56% increase from 2019.

Evidence Rating Level: 1 (Excellent)

Study Rundown:

Hearing loss is common and can negatively affect multiple aspects of an individual’s quality of life. Deafness in early life is associated with poor literacy outcomes and reduced employment opportunities in later life. Despite this, there is sparse literature on the prevalence of hearing loss making it difficult to understand who is affected and where resources need to be allocated. This study aimed to estimate the prevalence, severity, and distribution of global hearing loss and predict the course of this disease through 2050. Systematic reviews of population-representative surveys on hearing loss prevalence from 1990 to 2019 were conducted. According to study results, approximately one in five individuals globally had hearing loss in 2019, with a large proportion having moderate to severe loss after adjusting for hearing aid use. By 2050, an additional 1 billion people are projected to having hearing loss, despite age-standardized prevalence. Early interventions including childhood screening need to be implemented to ameliorate this burden. This study was limited by a lack of reporting from low-income countries which are likely to be most affected. It is possible that the prevalence of hearing loss worldwide by 2050 may be underreported. Nevertheless, this systematic review provides valuable insight into measures that can be implemented to alleviate the high prevalence of hearing loss worldwide.

In-depth [randomized controlled trial]:

Three DisMod-MR 2.1 models were run to estimate the prevalence of no hearing loss (0-19 dB), mild hearing loss (20-34 dB), and moderate-to-complete hearing loss (³35 dB). Five additional models were run for more severe levels of hearing loss: one for hearing aid coverage and another for age-related hearing loss. After severity-specific prevalence of hearing loss was adjusted to account for hearing aid usage, the prevalence of hearing loss due to underlying causes (otitis media, congenital birth defects, meningitis, and tinnitus) was predicted. Results were presented using the Healthcare Access and Quality (HAQ) Index based on data from 215 survey sources in 77 countries.

In 2019, an estimated 1.57 billion people (95%-unit interval [UI] 1.51-1.64) had hearing loss, accounting for 20.3% (95% UI 19.5-21.1) of the global population. The number of people with moderate-to-complete hearing loss increased from 225.3 million (95% UI 197.6-250.9) in 1990, to 403.3 million (95% UI 357.3-449.5) in 2019, representing a 79.1% (95% UI 73.8-84.1) increase. The greatest proportion of people with moderate-to-complete hearing loss resided in the Western Pacific region (127.1 million, 95% UI 112.3-142.6), followed be South-East Asia (103.4 million, 95% UI 90.9-115.4), and the Americas (58.8 million, 95% UI 51.7-66.2). Moreover, between 1990 and 2019, the years lived with disability (YLDs) attributable to hearing loss increased by 73.6% (95% UI 67.1-79.2), from 25.02 million (95% UI 16.96-35.34) to 43.45 million (95% UI 29.68-61.80). Hearing loss was most severe in individuals younger than 5 years and older than 70 years. Under 5 years of age, hearing loss was mostly due to otitis media (63.7%, 95% UI 56.9-70.2), whereas in adults aged 50-54 years, it was due to age-related factors (96.2%, 95% UI 94.5-97.6). By 2050, it is estimated that 2.45 billion people (95% UI 2.35-2.56) will have hearing loss. Thus, stronger healthcare provision mechanisms, such as childhood screening and hearing aids, are needed to reduce the burden of unaddressed hearing loss in countries that are impacted the most.

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