Prevalence, risk factors and burden of diabetic retinopathy in China: a systematic review and meta-analysis

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Figure 1

Systematic review flow diagram of studies on the prevalence of and risk factors for diabetic retinopathy (DR) in China. PHCM - Primary Health Care Management; *Reason 1 – Studies that were not community-based, PHCM-based or registry-based; *Reason 2 – Studies that were not based in China; *Reason 3 – Articles with no numerical prevalence measure of DR or didn’t report risk factor for DR in people with diabetes mellitus (DM); *Reason 4 – Studies with no clear assessment methods or grading systems of DR; *Reason 5 – Studies that were specifically conducted in people with unrepresentative characteristics (hypertensive patients, people with reduced vision, etc.); *Reason 6 – Multiple publications of the same study; *Reason 7 – Studies that didn’t include both newly detected and diagnosed DM cases.

Figure 2

Geographical distribution of included studies on prevalence of and risk factors for diabetic retinopathy (DR) in China.

Figure 3

Pooled prevalence of any diabetic retinopathy (DR) in general population and in people with DM by random-effects meta-analysis. There were 28 studies for synthesizing the prevalence of any DR in general population and 31 in people with DM.

Figure 4

Pooled prevalence of nonproliferative diabetic retinopathy (NPDR) in general population and in people with diabetes mellitus (DM) by random-effects meta-analysis. There were 14 studies for synthesizing the prevalence of NPDR in general population and 17 in people with DM.

Figure 5

Pooled prevalence of proliferative diabetic retinopathy (PDR) in general population and in people with diabetes mellitus (DM) by random-effects meta-analysis. There were 14 studies for synthesizing the prevalence of PDR in general population and 17 in people with DM.

Figure 6

Age-specific prevalence of any diabetic retinopathy (DR) in people with diabetes mellitus (DM) by random-effects meta-analysis. The numbers of individual studies contributing to the synthesis of prevalence in each age group are 4 (for 30-39 years), 10 (for 40-49 years), 15 (for 50-59 years), 16 (for 60-69 years), 10 (for 70-79 years) and 9 (for 80-89 years) respectively.

Figure 7

The prevalence of any diabetic retinopathy (DR) by diabetes mellitus (DM) duration group, using random-effects meta-analysis. The numbers of individual studies contributing to the synthesis of prevalence in each DM duration group are 13 (for newly diagnosed), 7 (for 1-4 years), 8 (for 5-9 years) and 9 (for ≥10 years) respectively.

Figure 8

Estimated regional number of middle-aged and older Chinese with any diabetic retinopathy (DR) and contributing age groups in 2010.