Prevalence of diabetic retinopathy in urban and rural India: a systematic review and meta analysis

Authors: Brar AS, Sahoo J, Behera UC, Jonas JB, Sivaprasad S, Das T.

Geographical coverage: India

Sector: Burden of disease

Sub-sector: Epidemiology, prevalence

Equity focus: Not reported

Study population: Patients with diabetes mellitus

Review type: Other review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background: Over 50 per cent of the population of India lives in rural areas. The prevalence of diabetes mellitus (DM) is increasing in rural as well as urban areas. However, this prevalence is unevenly distributed between higher and lower socioeconomic rural populations. Moreover, eye care services are scarce in rural areas of India. Thus, it is essential to explore the impact of DM on vision in the rural population.

Objectives: To estimate the prevalence of diabetic retinopathy (DR) in India’s urban and rural areas.

Main findings: The search identified 860 articles, of which 10 studies were included in this review for qualitative and quantitative analysis. Seven of 10 studies were conducted in south India, two studies in western India, and one study in eastern India. The overall prevalence of DR within the diabetic group in the included studies was 16.10% (95% CI, 13.16-19.04). The prevalence of DR was 17.44% (95% CI, 14.33-20.55) in urban and 14.00% (95% CI: 9.13-18.86) in rural populations; however, the difference between the two populations was not significant (p = 0.24). The pooled prevalence of DR in diabetic people in south India was 16.33% (95% CI: 12.02-20.63), while in west/east India, it was 15.24% (95% CI: 13.42-17.06). The authors noted a lower prevalence of DR in people with diabetes in the age group of 40 to 49 years (13.57%, 95% CI: 7.16-19.98) than in the age group of 50 to 59 years (16.72%, 95% CI: 12.80-20.64) and the age group of ≥60 years (16.55%, 95% CI: 12.09-21.00). The review authors noted a high level of heterogeneity. In addition, the publication bias test exhibited bias, indicating that the studies with negative results were not published. Based on the findings of this review, in particular, the narrow difference in the prevalence of DR in the rural and urban areas of India, the review authors recommended including comprehensive eye care along with screening of DR in the national programmes in India.

Methodology: An extensive literature search with an English language limit was conducted in Medline, Scopus and ScienceDirect databases to identify relevant articles published from 1 January  1990 and 10 April 2021. No geographical limits were applied. The population-based, peer-reviewed studies were conducted on participants residing in India, and reporting prevalence was included. The studies conducted only on patients with type 1 diabetes were excluded. The reviewers scanned reference lists of included studies to find relevant articles.

The title and abstract and full-text screening were conducted by two reviewers independently. The quality of included studies was assessed using the Joanna Briggs Institute (JBI) standardised critical appraisal checklist for prevalence studies. Data was extracted using a standardised spreadsheet designed in advance and coded as required. The study authors were contacted for missing/incomplete data.

The results were synthesised using inverse-variance random-effects model meta-analysis. Heterogeneity was assessed using I² and tau-squared statistics, and publication bias was assessed using funnel plot and Egger’s test.

Applicability/external validity: The review authors did not discuss the applicability or external validity of the results.

Geographic focus:

Studies included in the review were all conducted in India.

Summary of quality assessment:

The authors used an appropriate approach to synthesise the data of included studies, including heterogeneity assessment and publication bias. However, the literature searches were not comprehensive and language bias was not avoided by the review authors. Moreover, it is not clear if the authors employed a rigorous approach when extracting data of included studies. Therefore, a low confidence was placed in the conclusions about the effects of this review.