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Socioeconomic Inequality in the Global Burden of Refraction Disorders
abstract
This abstract is available on the publisher's site.
Access this abstract nowPURPOSE
To explore socioeconomic inequality in global burden of refraction disorders using disability-adjusted life years (DALYs).
METHODS
World Bank categorical and national DALY numbers, crude rates and age-standardized rates caused by refraction disorders between 1990 and 2017 were obtained. Gini coefficient and concentration index were computed to assess trends in global health inequality in refraction disorders burden.
RESULTS
Lower middle-income countries had the highest burden of refraction disorders and greatest decline in age-standardized DALY rates of 15.9% (171.0 in 1990; 143.8 in 2017), followed by upper middle-income countries, with a 9.7% decline (103.7 in 1990; 93.7 in 2017). High-income countries had the lowest age-standardized DALY rates (70.4 in 1990; 65.7 in 2017), while low-income countries had the lowest DALY numbers. Between-country inequality decreased, with Gini coefficient declining from 0.203 in 1990 to 0.184 in 2017. Socioeconomic-associated inequality also decreased, with concentration index changing from -0.060 in 1990 to -0.041 in 2017. Small peaks of DALY numbers and crude rates occurred in the age group of 5-9 years in countries with different income levels. An earlier occurrence of high peaks of DALY estimates in older adults had been observed in countries with lower income.
CONCLUSION
Middle-income countries are more burdened with refraction disorders but have achieved great progress in the last few decades. The global health improvement in refraction disorders has been accompanied by narrowing inequality. Older adults in lower income countries tend to suffer from refraction disorders at an earlier age, compared with older adults in higher income countries.
Additional Info
Disclosure statements are available on the authors' profiles:
Socioeconomic Inequality in the Global Burden of Refraction Disorders: Results From the Global Burden of Diseases Study 2017
Acta Ophthalmol 2020 Mar 01;[EPub Ahead of Print], X Tang, L Lou, Y Xu, K Jin, J Cao, J Shao, Z Gao, K YaoFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
There is a fundamental disconnect at the heart of all vision epidemiology publications that renders them almost unfathomable to most hard-working eye care practitioners and many policymakers: how can something so “simple” (refractive error) cause so much vision impairment? The authors note Global Burden of Disease (GBD) figures showing that uncorrected refractive error (URE) is the leading cause of moderate or severe vision impairment (116 million cases; 54% of the total) and the second largest cause of blindness (7 million cases; 21% of the total). In this article, the authors analyze and compare GBD data with World Bank data to explore this problem.
The analysis is granular, as it is based on aggregated data. For example, in analyzing the effect of average national income on the rate of vision impairment from URE, it is not possible for the authors to distinguish between refractive error prevalence (how many people have myopia, hyperopia, or astigmatism) and refractive correction rates (how many can access vision corrections). So, this is not a paper that will answer local questions about eye care workload or barriers to care. It takes a global view and sees some interesting patterns over 30 years.
Across countries, the burden of vision impairment from URE lessens as average income increases. The exception is low-income countries, which have far less burden than expected—this is probably due to lower refractive error rates rather than improved refractive correction rates, although this aggregated analysis cannot distinguish. This means that lower middle–income countries have the greatest burden of vision impairment from URE in the world.