Title: Prevalence of primary angle closure glaucoma in the last 20 Years: A meta-analysis and systematic review
Author: Zhang N, Wang J, Chen B, Li Y, Jiang B.
Geographical coverage: Italy, Tanzania, Singapore, South Africa, Thailand, Bangladesh, Poland, India, Japan, China, Myanmar, Brazil, Sri Lanka, Qatar, South Korea, Nepal, Nigeria, Israel, Iran and Northern Ireland.
Sector: Burden of disease
Sub-sector: Epidemiology, prevalence
Equity focus: Not reported
Study population: Patients with primary angle-closure glaucoma
Review type: Epidemiology review
Quantitative synthesis method: Meta-analysis
Qualitative synthesis method: Not applicable
Background: Glaucoma is a leading cause of irreversible blindness worldwide, with primary angle-closure glaucoma (PACG) being a significant contributor. The global prevalence of PACG was 0.5% in 2013, with estimates suggesting 23.36 million cases in 2020 and 32.04 million in 2040, with Asia accounting for the majority of cases. Various risk factors, including ethnicity, age, and sex, influence the prevalence of PACG, and these estimations have evolved with advancements in study design and diagnostic methods.
Objectives: To investigate the worldwide prevalence of PACG and its risk factors in the last 20 years.
Main findings: Overall, PACG affects more than 17 million people worldwide, especially leading to a huge burden on Asia.
The search identified a total of 1393 articles, of which 37 studies comprising of 144,354 individuals were included in this meta-analysis. The sample size in the included studies ranged from 790 to 15,122.
The global pooled prevalence of PACG was 0.6% (95% confidence interval [CI]: 0.5 to 0.8) for the last 20 years. The prevalence of PACG increases with age, with the highest prevalence (2.8%, 95% CI: 1.7 to 4.7, p<0.01) in people older than 80 years old and the lowest prevalence (0.1%, 95% CI: 0.1 to 0.3, p<0.01) in people aged 40–49 years compared with other age groups.
Men were found less likely to have PACG than women (risk ratio=0.71, 95% CI: 0.53 to 0.93, p<0.01). Asia had the highest prevalence of PACG (0.7%, 95% CI: 0.6 to 1.0) while Europe had the lowest PACG prevalence compared with other geographical areas (0.2%, 95% CI: 0.1 to 0.6). The current estimated global population with PACG in 2020 was 17.14 million (95% CI: 14.28 to 22.85) for people over 40 years old, of which 12.30 million (95% CI: 10.54 to 17.57) were in Asia. It is estimated that by 2050, the global population with PACG will be 26.26 million (95% CI: 21.88 to 35.01), with 18.47 million (95% CI: 15.83 to 26.39) in Asia.
Methodology: The literature search was conducted in Medline, Embase, and Web of Science to identify population-based cross-sectional or cohort studies on the prevalence of PACG, published in English from January 2000 to September 2020. Identified studies were screened against the eligibility criteria. Reference lists of the included studies were scanned to identify additional relevant publications. Two reviewers independently extracted relevant data from the included studies, and study quality was assessed using The Quality In Prognosis Studies (QUIPS) tool. The findings were synthesised using random-effects meta-analysis. Heterogeneity was assessed using I2 statistics, and publication bias was evaluated using the funnel plots, P-curve analysis, and Egger’s test.
Applicability/external validity: The review examined the applicability and external validity of its findings, highlighting that there was a single study for South America and three studies for Europe. Furthermore, the review noted the absence of data from North America and Oceania.
Geographic focus: Included studies were conducted in Italy, Tanzania, Singapore, South Africa, Thailand, Bangladesh, Poland, India, Japan, China, Myanmar, Brazil, Sri Lanka, Qatar, South Korea, Nepal, Nigeria, Israel, Iran and Northern Ireland.
Summary of Quality Assessment: The conclusions regarding the effects of this study are met with low confidence. The search was limited to articles published in English, and the review authors did not indicate the number of reviewers involved in screening the articles. Furthermore, they did not provide a list of excluded studies or report whether they contacted authors or experts. Additionally, the results were not analysed or reported according to the risk of bias status.
