Prevalence of cataract and cataract surgery in urban and rural Chinese populations over 50 years old: a systematic review and Meta-analysis

INTRODUCTION

C ataract was one of the main causes of blindness which remained a major public health problem worldwide.The prevalence of cataract in developing countries was higher and the age of onset was earlier, Asia contributed the majority particularly. In China, cataract was the leading cause of low vision and blindness. Cataract were the primary causes of visual impairment in adults over 60 years old, despite the continuous efforts of public health to improve the cataract surgery rate. In terms of economic burden, most countries faced serious economic burden and global health progress in cataract was accompanied by widening inequality, with cataract burden being more concentrated in countries with lower socioeconomic status. China also endured a huge economic burden based on the number of patients. This made the cost of medical treatment and social impact caused by cataract blindness lead to serious damage to the economy all over the world. Although cataract was not fatal, it still had a negative influence on the quality of life in cataract patients.The most common cause of cataract was the denaturation of protein which led to the opacity in lens. It was commonly observed in people over 50 years old, and the morbidity increases with age. Its occurrence was linked to the degeneration of metabolism in the elderly. So cataract had a profound impact on the quality of life of the elderly in pace with age. Figuring out a way to investigate the prevalence of cataract and further guide cataract screening to improve the quality of life will be one of the urgent challenges which China needs to face. Since the 1990s, Chinese researchers had started to survey and analyze the prevalence of cataract in many areas, and the results explained that cataract was still the main cause of blindness. With the increasing proportion of the elderly in the population, the number of cataract patients in China would increase year by year, and the increasingeconomic burden caused by cataract was an inevitable problem. The prevalence of cataract and cataract surgical coverage has significant disparities among different regions and nationalities. However, the research on the prevalence and cataract surgical coverage in China has not been integrally analysed, which also limited the extensive cataract screening and popularization of cataract surgery in the future.In order to further analyses the prevalence of cataract and reduce the economic burden, it was necessary to investigate the epidemiology of cataract. The purpose of this study was to summarize and analyses the research on the prevalence of cataract in China, expecting to get a preliminary assessment of the prevalent trend and provide a theoretical evidence for further cataract screening.

SUBJECTS AND METHODS

Cataract surgical coverage represents the coverage of cataract surgery among cataract patients. Ⅰt reflects the popularity of cataract surgery in study area, but do not distinguish the types of surgery and regions in this Meta-analysis. The results showed that the median of cataract surgical coverage in China was 7.18%, the lowest was 3.47%, and the highest was 17.69%. Heterogeneity test showed that there was statistical difference between the included studies (=97.1%,<0.01). Meta-analysis after using random effect model showed that the cataract surgical coverage in China was 9.19% (95%CI: 7.16%-11.22%). Forest map was shown in Figure 11.

The literature was collected and screened by Endnote X9, then the related literature was screened according to the inclusion and exclusion criteria. After that, titles and abstracts of the remaining studies would be independently scanned by three authors (Du YF, Liu HR and Zhang Y). In this step, literature was selected subjectively in order to judge whether it is related to this Meta-analysis. These selected literatures would be compared, and inconsistent problems were solved through negotiation. Then we read the full text of the remaining studies to determine whether they met our inclusion criteria,but studies that were not available for the full text would be excluded. Finally, according to Chinese urban and rural classification standards (Chinese administrative divisions, the scale of county and above was urban, and the scale of village and township was rural), the literature was divided into urban and rural categories.

In this study, the data were extracted on the basis of prescribed process, which the details were shown in Table 2. Quality assessment was based on the quality assessment criteria proposed by Khambalia and Seen, and the results of quality score were as follows: 2 papers scored 1, 7 papers scored 2,9 papers scored 3, 1 paper scored 4, and 1 papers scored 5(Figure 3).

The inclusion criteria were as follows:1) The purpose of these literature was to investigate the prevalence of cataract in China, and the cases included were consecutive; 2) The sampling method should be random sampling, and subjects were healthy people in a stationary region; 3) The subjects were aged 50 or above, and were stratified according to different age groups; 4) The diagnosis method of cataract was reasonable and met the standard(Figure 1); 5) The prevalence of cataract can be directly extracted or can be calculated from the original data.

The exclusion criteria were as follows:1) Research method was cohort study, or the study type was “comments”, “letter”, “review”, “case report”,; 2)Repetitive articles or duplicate studied population from the identical area; 3) Had tendency when select the studied population; 4) Research data were incomplete.

We extracted the basic data of the final qualified literature, including the author, publish year, study region, regional category, age, sample size, literature quality score,. And research data were extracted from the literature include the number of samples older than 50y, the number of cataract patients and the prevalence.

The quality of included studies was evaluated using the quality assessment criteria of literature proposed by Khambalia and Seen. Then the included literature was scored and summarized according to these criteria (Table 1).

Other data: We also collected and collated the other data of some literature in this Meta-analysis, including the prevalence of cataract in urban and rural areas respectively, the prevalence of cataract in different age groups, and the cataract surgical coverage.

開展教學活動的前提是系統地研究學生的學情。學情分析是系統工程，既要了解學生學習的起點狀態，又要研究學生的潛在狀態。學生的學習起點狀態包括學生的認知基礎、學習能力、學習態度、學習習慣、意志品質等。學生的潛在狀態指學生可能發生的狀況與可能的發展，主要說明學生在知識與技能，過程與方法，情感、態度與價值觀方面都能參與到什么程度，達到什么狀態等。

第一代路虎發現僅擁有三門版一種車身形式，但幾乎所有人都明白在不久的將來，它會得到空間靈活度更高，駕乘體驗更為優秀的五門版車型。

Cataract was one of the main causes of blindness in the world,which accounts for about half of the entire blind people.But the prevalence of cataract in China varies markedly due to regional distribution and examination methods. Metaanalysis was still developing in the world for a short time,when there were not enough time or funds to do a national survey, we can make a Meta-analysis of the results from the existing local epidemiologic surveys to increase the sample size and the diagnostic efficiency, make the research results have statistically significant. This Meta-analysis showed that the pooled prevalence of cataract in China was 27.45%(95%CI: 24.38%-30.52%), which was similar to the results of most previous epidemiological studies in the world. And with the increase of age, the prevalence of cataract increased significantly. Based on the large number of cataract patients in China, the cataract surgical coverage still has room for improvement compared with many countries and regions(Table 3).

RESULTS

Totally 20 studies were finally included for Meta-analysis through literature screening.The detailed screening process was shown in Figure 2. The total number of participants in all studies contained in this Meta-analysis was 111 434, and 31 551 were cataract patients.Among these studies, the minimum sample size was 279, and the maximum sample size was 20 860, of which the median was 5010, and the interquartile range was 2413-5300. The epidemiological investigations involved in these studies were distributed in the urban and rural areas of 15 provinces or cities, including Beijing, Zhejiang, Guangdong, Hainan, Hebei,Heilongjiang, Jiangsu, Jiangxi, Ningxia, Shandong, Shanghai,Sichuan, Tianjin, Yunnan, and Chongqing. The median prevalence of cataract was 28.81%, the lowest was 15.57%, the highest was 39.86%, and the interquartile range was 21.96%-32.77%.

轉錄因子在異戊二烯代謝生物合成中起著重要作用，這些因子結合特殊結構基因功能，調控相關基因的協同表達，刺激或抑制異戊二烯化合物的積累.本研究找到了多個與異戊二烯代謝類物質代謝有關的轉錄因子，為借助細胞懸浮培養技術生產青錢柳三萜類、多糖與戊烯苷等生物活性成分，并通過調控次生代謝相關基因表達獲得較高的產量提供了參考.

Heterogeneity analysis showed that the prevalence of cataract was statistical heterogeneity among these studies(=99.2%,<0.01), so the random effect model was used in Meta-analysis. The results showed that the prevalence of cataract over 50 years old in China was 27.45% (95%CI:24.38%-30.52%). Forest map was shown in Figure 4.

The median prevalence of cataract was 28.97%in rural areas, and the lowest was 22.40%, the highest was 34.95%. Heterogeneity test showed that there was statistical difference between the included studies (=97.8%,<0.01),so the random effect model was used for Meta‐analysis. The results showed that the prevalence of cataract in rural areas was 28.79% (95%CI: 25.45%-32.12%). The median prevalence of cataract was 26.17% in urban areas, and the lowest was 15.57%, the highest was 35.76%. Heterogeneity test showed that there were statistical differences among these studies(=99.4%,<0.01). Meta-analysis showed that the prevalence of cataract in urban areas was 26.66% (95%CI: 21.99%-31.34%). Forest maps were shown in Figures 5 and 6.

The prevalence of cataract in different age groups was statistically analysed base on the length of 10y. Results showed that the median prevalence of cataract in 50-59 age group was 5.23%,the lowest prevalence was 2.39%, and the highest prevalence was 16.81%. The heterogeneity test showed that there was statistical difference between the included studies (=98.8%,<0.01). Meta-analysis using random effect model showed that the prevalence of cataract in the age group of 50-59y was 7.88% (95%CI: 5.59%-10.18%). The median prevalence of cataract in 60-69 age group was 25.37%, the lowest was 10.90%, and the highest was 42.14%. Heterogeneity test showed that there was statistical difference between the included studies (=99.1%,<0.01). So Meta-analysis showed that the prevalence of cataract was 24.94% (95%CI:20.28%-29.60%). The median prevalence of cataract in 70-79 age group was 50.72%, the lowest was 41.47%, and the highest was 69.44%. Heterogeneity test showed that there was statistical difference between the included studies (=97.4%,<0.01). Meta-analysis showed that the prevalence of cataract in 70-79 years old was 51.74% (95%CI: 45.75%-57.72%).The median prevalence of cataract over 80 years old was 82.42%, the lowest was 64.84%, and the highest was 85.71%.Heterogeneity test showed that there was statistical difference between the included studies (=87.3%,<0.01). So Metaanalysis showed that the prevalence of cataract over 80 years old was 78.43% (95%CI: 74.02%-82.83%). Forest maps were shown in Figures 7-10.

We searched PubMed, EMBASE, Web of Science, Wanfang Data, and CNKI for literature about the prevalence of cataract in China. In order to cover comprehensive related literature as much as possible, the search terms were set as“cataract” or “cataracts” and “prevalence” or “epidemiology” or“incidence” and “China” or “Chinese”. The time of publication was limited from July 2000 to July 2020, and the language of publication was English.

當然，換在以前，穿幫的只是公開發表的文稿，而那些數量更多的內部使用或僅用于存檔備查的文案，則幾乎無人關注，即使偶爾露出馬腳，人們也只是一笑了之，后果嚴重不到哪里去。也正是因為如此，偷懶的人繼續偷懶，偷文的人照偷不誤，各類奇葩新聞時時曝光，為豐富多彩的生活平添若干生動素材。

The publication bias of this study was analysed by Eggers’ test. Results of Eggers’ test showed that=-0.22,=0.826,>0.05, so there was no significant publication bias. Funnel plot of publication bias was shown in Figure 12.

第二種方案，將基帶矩陣作為整個傳輸系統的核心，周邊配置IP和SDI的轉換設備來實現兩種信號之間的轉換。這……