Retinal vein occlusion (RVO) is the second most common retinal vascular disorder that affected 16.4 million people worldwide in 2008. The last decade has seen new epidemiological data on RVO, enabling us to provide a contemporary estimation of RVO epidemiology. We searched PubMed, Medline, Embase, GLOBAL HEALTH, World Health Organization Global Health Library, China National Knowledge Infrastructure for studies that reported prevalence or incidence of RVO in the general population. The age- and sex-specific prevalence of RVO was estimated by a multilevel mixed-effects logistic regression, the incidence of RVO and potential risk factors for RVO were respectively pooled by a random-effects meta-analysis. The prevalence of any RVO, branch RVO (BRVO) and central RVO (CRVO) all increased with advanced age, but didn't differ significantly between sexes. In 2015, the global prevalence of any RVO, BRVO and CRVO in people aged 30-89 years was 0.77% (95% confidence interval CI = 0.55-1.08), 0.64% (95% CI = 0.47-0.87) and 0.13% (95% CI = 0.08-0.21), equivalent to an overall of 28.06 million, 23.38 million and 4.67 million affected people. For any RVO, the pooled five-year cumulative incidence was 0.86% (95% CI = 0.70-1.07) and the pooled ten-year cumulative incidence was 1.63% (95% CI = 1.38-1.92). Hypertension was the strongest risk factor for any RVO, with a meta- odds ratio (OR) of 2.82 (95% CI = 2.12-3.75). This study provides an updated summary of RVO epidemiology in the general population. More epidemiological studies worldwide are still needed to better understand the global disease burden of RVO.

Diabetic retinopathy (DR), the primary retinal vascular complication of diabetes mellitus (DM), is a leading cause of vision impairment and blindness in working-age population globally. Despite mounting concerns about the emergence of DM as a major public health problem in the largest developing country, China, much remains to be understood about the epidemiology of DR. We aimed to investigate the prevalence of and risk factors for DR, and estimate the burden of DR in China in 2010. China National Knowledge Infrastructure (CNKI), Wanfang, Chinese Biomedicine Literature Database (CBM-SinoMed), PubMed, Embase and Medline were searched for studies that reported the prevalence of and risk factors for DR in Chinese population between 1990 and 2017. A random-effects meta-analysis model was adopted to pool the overall prevalence of DR. Variations in the prevalence of DR in different age groups, DM duration groups and settings were assessed by subgroup meta-analysis and meta-regression. Odds ratios (ORs) of major risk factors were pooled using random-effects meta-analysis. The number of people with DR in 2010 was estimated by multiplying the age-specific prevalence of DR in people with DM with the corresponding number of people with DM in China. Finally, the national number of people with DR was distributed into six geographic regions using a risk factor-based model. A total of 31 studies provided information on the prevalence of DR and 21 explored potential risk factors for DR. The pooled prevalence of any DR, nonproliferative DR (NPDR) and proliferative DR (PDR) was 1.14% (95% CI = 0.80-1.52), 0.90% (95% CI = 0.56-1.31) and 0.07% (95% CI = 0.02-0.14) in general population; In people with DM, the pooled prevalence rates were 18.45% (95% CI = 14.77-22.43), 15.06% (95% CI = 11.59-18.88) and 0.99% (95% CI = 0.40-1.80) for any DR, NPDR and PDR, respectively. The prevalence of any DR in DM patients peaked between 60 and 69 years of age, and increased steeply with the duration of DM. DM patients residing in rural China were at a higher risk to have DR than those in urban areas. In addition, insulin treatment, elevated FBG level and higher HbA1c concentration were confirmed to be associated with a higher prevalence of DR in people with DM, with meta-ORs of 1.99 (95% CI = 1.34-2.95), 1.33 (95% CI = 1.12-1.59) and 1.15 (95% CI = 1.09-1.20) respectively. In 2010, a total of 13.16 million (95% CI = 8.95-18.00) Chinese aged 45 years and above were living with DR, among whom the most were in South Central China and the least were in Northwest China. DR has become a serious public health problem in China. Optimal screening of and interventions on DR should be implemented. Improved epidemiological studies on DR are still required.

Dry eye disease (DED) is one of the most prevalent ocular diseases in the world. In China, new lifestyles driven by information technology and the rapid ageing process have brought DED a severe public health concern. The aim of our study was to obtain the pooled prevalence of DED in China and explore its potential correlates. A comprehensive systematic review was conducted to identify all relevant literature published since 1990. Meta-analysis and meta-regression approaches were adopted to estimate the prevalence of DED. The number of people with DED was obtained by multiplying the corresponding demographic data in 2010. Advanced age, female sex and larger latitude were significant risk factors for DED by symptoms and signs, whereas only advanced age was positively associated with an increased prevalence of DED by symptoms. In 2010, the prevalence of DED by symptoms and signs were 13.55% (95% CI = 10.00-18.05) and that of DED by symptoms was 31.40% (95% CI = 23.02-41.13) in Chinese people aged 5-89 years, corresponding to a total of 170.09 million (95% CI = 125.52-226.63) and 394.13 million (95% CI = 288.99-516.30) affected individuals respectively. The huge burden of DED in China calls for more public health attention and actions. Improved epidemiological studies on DED prevalence are still urgently needed.

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. 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. 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. 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.

The temporal trend of inflammatory bowel disease (IBD) incidence is reported to be increasing in worldwide regions; however, reports focusing on China are sparse. The aim of this study was to provide an overview of the disease burden and clinical features of IBD in the Chinese population. We searched Medline, EMBASE, and another two Chinese databases. A parallel literature review and data extraction were conducted. Meta-analysis was performed to estimate the summary incidence rate of Crohn’s disease (CD) and ulcerative colitis (UC). The constituent ratios with 95% CI were calculated for clinical phenotypes and classifications. The literature review included 47 publications. The summary incidence rate of IBD was 1.74 (95% CI: 1.08; 2.40) per 100,000 person years, and the corresponding incidence rates of CD and UC were 0.40 (95% CI: 0.23; 0.57) and 1.18 (95% CI: 0.81; 1.56) per 100,000 person years, respectively. The sex distribution analysis indicated a male predominance in both CD (sex ratio: 1.64; 95% CI: 1.47–1.84) and UC (sex ratio: 1.29; 95% CI: 1.21–1.38). The clinical characteristics were summarized using data from 2283 CD cases and 17,958 UC cases; in which the majority of CD patients were diagnosed between 17–40 years of age, with non-stricturing and non-penetrating disease, varied disease locations, and less extra-intestinal manifestation. UC cases were featured with later disease diagnosis, a more severe disease course, more segmental lesions, and less extra-intestinal manifestations. Our study provided an estimated disease burden of IBD and demonstrated distinct clinical features in the Chinese population. Large-scale population-based studies are needed to further evaluate these findings.

Peripheral artery disease (PAD), the third leading cause of atherosclerotic vascular morbidity, affects approximately 202 million people worldwide, among whom more than two-thirds reside in low- and middle-income countries (LMIC). For China, the largest developing country, little is known about the epidemiology of PAD. We aimed to estimate the prevalence of PAD and the number of affected people in China, establish the main risk factors for PAD and assess the number of people with PAD at the sub-national level. We searched China National Knowledge Infrastructure (CNKI), Wanfang, Chinese Biomedicine Literature Database (CBM-SinoMed), PubMed, Embase and Medline for population-based studies that have reported the prevalence of PAD in the general Chinese population from 1990 onwards. PAD was defined as an ankle-brachial index (ABI) lower than or equal to 0.90. We used a multilevel mixed-effects logistic regression to generate the gender- and age-specific prevalence of PAD, and a random-effects meta-analysis to pool the odds ratios (ORs) of major risk factors. United Nations population numbers were used to estimate and project the number of affected people from 2000 to 2020. Finally, we used the risk factors-based model to distribute the national number of people with PAD into different settings (urban and rural) and regions (East, Central and West) for the year 2010. Overall, 37 articles met all inclusion criteria and provided prevalence estimates, among which 14 also explored risk factors for PAD. The prevalence of PAD increased gradually by age until mid-60s, after which the increase accelerated. In males, the prevalence of PAD ranged from 2.81% (95% CI = 1.77-4.43) in those aged 25-29 years to 21.95% (95% CI = 15.39-30.31) in those 95-99 years old. In females, the PAD prevalence increased from 3.84% (95% CI = 2.44-5.98) in those aged 25-29 years to 27.95% (95% CI = 20.14-37.37) in those aged 95-99 years. The PAD prevalence was consistently higher in females than in males across all age groups. This difference was most significantly pronounced among the elderly, starting from 60 years. Between 2000 and 2020, the total number of Chinese people with PAD is expected to increase by 40%: from 29.44 million (95% CI = 22.51-38.62) in 2000 to 41.13 million (95% CI = 32.00-52.95) in 2020. Current smoking was the strongest risk factor for PAD, with a meta-odds ratio (OR) of 2.62 (95% CI = 1.44-4.76), followed by hypertension (1.94, 95% CI = 1.48-2.53) and diabetes (1.71, 95% CI = 1.45-2.01). In 2010, 15.18 million (95% CI = 11.74-19.67) people with PAD resided in the East China, 11.08 million (95% CI = 8.61-14.28) in the Central China and 8.65 million (95% CI = 6.71-11.16) in the West China. In addition, 24.20 million (95% CI = 18.82-31.16) people with PAD were living in rural areas, accounting for almost 70% of all PAD cases in China. With rapid ageing in China, PAD has become a serious public health problem. More research and optimal interventions on PAD are required to better identify effective strategies for prevention and treatment of PAD in China.