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Study the past if you would define the future (Confucius)
  1. Tiarnan D Keenan,
  2. Emily Y Chew
  1. Division of Epidemiology and Clinical Applications, National Eye Institute/National Institutes of Health, Bethesda, Maryland, USA
  1. Correspondence to Dr Emily Y Chew, National Eye Institute/National Institutes of Health, Bethesda, Maryland, USA; echew{at}nei.nih.gov

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Li et al 1 reported the results of an elegant study to estimate the prevalence and incidence of age-related macular degeneration (AMD) in the European Union (EU), where AMD is the leading cause of legal blindness and visual impairment. Importantly, the second objective was to predict future EU prevalence and incidence figures out to the year 2050.

How did they do it?

The authors performed a systematic review and identified relevant articles in the literature: 22 prevalence but only four incidence studies. Since different studies used different AMD classification systems, the authors recategorised the data according to the Beckman Initiative for Macular Research system.2 They then synthesised the data by meta-analysis to obtain prevalence and incidence estimates by AMD stage. Specifically, they used random-effects meta-analysis, which assumes that results vary between studies not just from random error but also from true variation (ie, ‘heterogeneity’, from differences in study protocols, regions, etc). Next, they performed random-effects meta-regression to investigate potential sources of heterogeneity.

In this way, the authors derived population prevalence estimates, expressed as percentages, for early/intermediate AMD, late AMD, neovascular AMD and geographic atrophy (GA). They reported incidence estimates in a similar way, but only for late AMD. To obtain estimates for the actual numbers of people with AMD, they applied their age-stratified prevalence and incidence estimates to current Eurostat population estimates. Similarly, they used Eurostat population projections to estimate how many EU individuals might be affected by AMD in the future.

What were the main findings?

The current prevalence of early/intermediate AMD in EU adults aged 60 years and older was estimated at 25.3%, while that for late AMD was 2.4%. This corresponds to 67 million individuals with AMD, comprising 56.7 million with early/intermediate AMD and 10.2 million with late AMD. The annual incidence of late AMD was estimated at 1.4 per 1000 individuals, which corresponds to 400 000 new cases per …

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Footnotes

  • Contributors Conception or design of the manuscript: TK and EC. Acquisition, analysis or interpretation of data: TK and EC.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.

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