Dual sensory impairment: Global prevalence, future projections, and its association with cognitive decline

There is rising public health concern surrounding dual sensory impairment (DSI), or comorbid hearing and vision impairments. Its global prevalence and the magnitude of its association with cognitive decline (CD) is unclear. Three databases were searched for epidemiological studies examining DSI prevalence or its association with CD. Independent reviewers selected studies, extracted data, and evaluated bias. Random-effects meta-analyses were performed. Projections were estimated using United Nations data. The population attributable fraction of DSI-associated CD was calculated. Among 43 studies with 5,246,796 participants, clinically assessed DSI prevalence was 5.50% (95% confidence interval [CI] = 2.88%-10.26%), with regional/ethnic/age variations. DSI prevalence is projected to increase by 27.2% from 2025 to 2050. Approximately 59.83% (95%CI = 41.03-76.12) of DSI patients had cognitive impairment. Baseline DSI was associated with incident CD (odds ratio [OR] = 1.72, 95%CI = 1.37-2.15). Globally, 3.81% (95%CI = 1.05-10.55) of incident CD may be attributed to DSI. DSI is globally prevalent, growing, and associated with CD, highlighting the need for better health policy and resource allocation. HIGHLIGHTS: The global prevalence of DSI is 5.50%, with geographical, ethnical and age variations. The prevalence of DSI rises with age and is projected to increase by 27.2% by 2050. Approximately 60% of individuals with DSI may have measurable cognitive impairment. DSI was associated with a 72% greater longitudinal risk of incident CD. Globally, 3.81% of CD cases may be attributable to DSI.