National and subnational prevalence and burden of glaucoma in China: A systematic analysis

Background Glaucoma, the second leading cause of blindness, affects approximately 64.3 million individuals worldwide. In China, demographic ageing is in rapid progress. Yet detailed and up-to-date estimates of the scale of glaucoma are rare. We aimed to quantify and understand the prevalence and burden of glaucoma in China from 1990 to 2015, with projections until 2050. Methods For this systematic review and meta-analysis, we searched China National Knowledge Infrastructure (CNKI), Wanfang, Chinese Biomedicine Literature Database (CBM-SinoMed), PubMed, Embase and Medline using comprehensive search strategies to identify all relevant articles that have reported the prevalence of glaucoma in the general Chinese population. We used a multilevel mixed-effect meta-regression to estimate the prevalence rates of primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG), and a random-effects meta-analysis to pool the overall prevalence of secondary glaucoma. United Nations population data were used to estimate and project the number of people with glaucoma from 1990 to 2050. Univariable and multivariable meta-regressions were conducted to assess the association between the prevalence of POAG and PACG and relevant demographic and geographic factors. The national burden of POAG and PACG in the years 2000 and 2010 were distributed to six geographic regions accordingly. Results From 1990 to 2015, the prevalence of all glaucoma ranged from 2.59% (95% CI = 1.96-3.49) to 2.58% (95% CI = 1.94-3.47). For different subtypes of glaucoma, the overall prevalence of POAG ranged from 1.03% (95% CI = 0.67-1.58) in 1990 to 1.02% (95% CI = 0.67-1.57) in 2015, PACG from 1.41% (95% CI = 1.18-1.68) to 1.40% (95% CI = 1.17-1.68). The overall prevalence of secondary glaucoma was 0.15% (95% CI = 0.10-0.23) during this period. The number of people with all glaucoma in China was 5.92 million (95% CI = 4.47-7.97) in 1990, and 13.12 million (95% CI = 9.88-17.68) in 2015. This increasing trend was also witnessed in different subtypes of glaucoma. The number of people affected by POAG increased from 2.35 million (95% CI = 1.54-3.60) in 1990 to 5.22 million (95% CI = 3.40-7.98) in 2015, PACG from 3.22 million (95% CI = 2.70-3.84) to 7.14 million (95% CI = 5.97-8.53), and secondary glaucoma from 0.34 million (95% CI = 0.23-0.53) to 0.76 million (95% CI = 0.51-1.17). In 2015, more than half (54.42%) of the glaucoma cases were PACG, followed by POAG (39.79%) and secondary glaucoma (5.79%). By 2050, the number of all glaucoma cases in China will be 25.16 million (95% CI = 18.96-33.86). In the multivariable meta-regressions, the odds ratio (OR) for each decade's increase in age was 1.43 (95% CI = 1.33-1.55) for POAG, and 1.65 (95% CI = 1.51-1.80) for PACG; males were more likely to have POAG (OR 1.36, 95% CI = 1.17-1.59), but less likely to have PACG (OR 0.53, 95% CI = 0.46-0.60) compared with females. After adjustment of age and gender, people living in urban areas were more likely to have POAG compared with those in rural areas (OR 1.54, 95% CI = 1.02-2.35). People in Northeast China were at a higher risk (OR 1.77, 95% CI = 1.07-2.94) of having PACG than people in East China. Among the six regions, East China owed the most POAG and PACG cases, whereas Northwest China owed the least. Conclusions This systematic review and meta-analysis suggests a substantial burden of glaucoma in China, with great variances among the different age groups, genders, settings and geographic regions. With the dramatic ageing trend in the next three decades, the prevalence and burden of glaucoma will continue to increase. More elaborate epidemiological studies are needed to optimise public health strategies for mitigating this important health problem.