The Prevalence of Diabetic Retinopathy in Australian Adults with Self-Reported Diabetes: The National Eye Health Survey

Abstract

Purpose: To determine the prevalence of and factors associated with diabetic retinopathy (DR) among non-Indigenous and Indigenous Australian adults with self-reported diabetes.

Design: Population-based cross-sectional study.

Participants: Non-Indigenous Australians (50-98 years of age) and Indigenous Australians (40-92 years of age) with known diabetes.

Methods: Diabetes was determined based on self-report of previous diagnosis of the disease. Nonmydriatic fundus photographs were obtained of each eye and graded according to the modified Airlie House classification system.

Main outcome measures: Any DR, vision-threatening DR (VTDR), treatment coverage rates (proportion of participants with proliferative DR [PDR], clinically significant macular edema [CSME], or both who had evidence of retinal scatter and focal laser treatment).

Results: Four hundred thirty-one non-Indigenous Australians (13.9%) and 645 Indigenous Australians (37.1%) self-reported diabetes, of whom 93% (1004/1076) had retinal images that were gradable for DR. The sampling weight-adjusted prevalence of any DR and VTDR among non-Indigenous adults with self-reported diabetes was 28.5% (95% confidence interval [CI], 22.6-35.3) and 4.5% (95% CI, 2.6-7.9), respectively. Among adults 40 years of age and older, the sampling weight-adjusted prevalence of any DR and VTDR was 39.4% (95% CI, 33.1-46.1) and 9.5% (95% CI, 6.8-13.1), respectively. Longer diabetes duration was associated significantly with VTDR in the Indigenous Australian population (odds ratio [OR], 1.08 per 1-year increase; P = 0.005) and non-Indigenous Australian population (OR, 1.05 per 1-year increase; P = 0.03). The treatment coverage of PDR and CSME was 75% (56/75) in Indigenous Australians and 79% (15/19) in non-Indigenous Australians. Diabetic retinopathy was attributed as the main cause of vision loss (<6/12 in the better eye) in 9% and 19% of non-Indigenous and Indigenous Australian adults with known diabetes, respectively.

Conclusions: Three quarters of non-Indigenous and Indigenous Australian adults with PDR or CSME have received laser treatment. The prevalence of VTDR in Indigenous and non-Indigenous Australians in the present study was lower than that found in previous population-based reports, nevertheless, approximately 1 in 10 Indigenous adults with known diabetes experience VTDR. This highlights that intensified prevention strategies are required to delay or prevent avoidable vision loss resulting from DR in Indigenous Australian communities.