Differences in retinopathy prevalence and progression between Anglo-Celt and Aboriginal Australians: the Fremantle Diabetes Study Phase II

Retinopathy prevalence, incidence and trajectories in type 2 diabetes: The Fremantle diabetes study phase II

AIMS

To determine diabetic retinopathy (DR) prevalence, incidence, and whether distinct trajectories are associated with DR-complicating Type 2 diabetes.

METHODS

Retinal photographs from Fremantle Diabetes Study Phase II (FDS2) participants with Type 2 diabetes recruited in 2008-2011 and who attended biennial assessments for up to 6 years were graded as no DR, mild non-proliferative DR (NPDR), moderate NPDR or severe NPDR/proliferative DR. Baseline DR prevalence, and the cumulative incidence of moderate NPDR or worse in those without DR at baseline, were calculated. Group-based DR trajectory modelling was performed. Logistic regression determined independent associates of incident moderate NPDR or worse and trajectory group membership.

RESULTS

Of 1521 participants (mean age 65.6 years, 52.1% males, median diabetes duration 9.0 years; 98% of all FDS2 participants with Type 2 diabetes) with gradable baseline photographs, 563 (37.0%) had DR. During a median 6.1 years of follow-up, 23 (3.2%) without baseline DR developed at least moderate NPDR (crude incidence 6.1/1000 person-years) with HbA1c the sole independent predictor (odds ratio [95% CI]: 1.62 [1.30-2.02] per 1% [11 mmol/mol] increase). Trajectory analysis showed two distinct groups, those with baseline/persistent DR (20%) and those remaining DR free (80%). Longer diabetes duration, insulin use, higher mean HbA1c , higher mean systolic blood pressure and higher mean urinary albumin: creatinine ratio all increased the odds (p ≤ 0.014) of being in the persistent DR trajectory group.

CONCLUSIONS

The low incidence of at least moderate NPDR reflects the trajectory analysis. The currently recommended biennial retinal screening frequency for individuals without DR could potentially be extended.

Proportion of people with diabetic retinopathy and macular oedema varies by ethnicity in a tertiary retinal clinic in Australia: findings from the Liverpool Eye and Diabetes Study (LEADS)

OBJECTIVE

There are limited data on the influence of ethnicity on diabetic retinopathy (DR). We sought to determine the distribution of DR by ethnic group in Australia.

DESIGN

Clinic-based cross-sectional study.

SETTING

Participants with diabetes in a defined geographical region of Sydney, Australia, who attended a tertiary retina referral clinic.

PARTICIPANTS

The study recruited 968 participants.

INTERVENTION

Participants underwent a medical interview and retinal photography and scanning.

PRIMARY OUTCOME MEASURES

DR was defined from two-field retinal photographs. Diabetic macular oedema (DMO) was defined from spectral domain optical coherence tomography (OCT-DMO). The main outcomes were any DR, proliferative DR (PDR), clinically significant macular oedema (CSME), OCT-DMO and sight-threatening DR (STDR).

RESULTS

There was high proportion of any DR (52.3%), PDR (6.3%), CSME (19.7%), OCT-DMO (28.9%) and STDR (31.5%) in people attending a tertiary retinal clinic. Participants of Oceanian ethnicity had the highest proportion of any DR and STDR (70.4% and 48.1%, respectively), while the lowest proportion was in participants of East Asian ethnicity (38.3% and 15.8%, respectively). Proportion of any DR and STDR in Europeans was 54.5% and 30.3%, respectively. Independent predictive factors for diabetic eye disease were ethnicity, longer duration of diabetes, higher glycated haemoglobin and higher blood pressure. Even after adjusting for risk factors, Oceanian ethnicity remained associated with twofold higher odds of any DR (adjusted OR 2.10, 95% CI 1.10 to 4.00) and all other forms of DR including STDR (adjusted OR 2.22, 95% CI 1.19 to 4.15).

CONCLUSION

In people attending a tertiary retinal clinic, the proportion of people with DR varies among ethnic groups. The high proportion in persons of Oceanian ethnicity suggests a need for targeted screening of this at-risk group. In addition to traditional risks factors, ethnicity may be an additional independent predictor of DR.

Prevalence of Diabetic Retinopathy in Indigenous and Non-Indigenous Australians: A Systematic Review and Meta-analysis

TOPIC

This systematic review and meta-analysis summarizes evidence relating to the prevalence of diabetic retinopathy (DR) among Indigenous and non-Indigenous Australians.

CLINICAL RELEVANCE

Indigenous Australians suffer disproportionately from diabetes-related complications. Exploring ethnic variation in disease is important for equitable distribution of resources and may lead to identification of ethnic-specific modifiable risk factors. Existing DR prevalence studies comparing Indigenous and non-Indigenous Australians have shown conflicting results.

METHODS

This study was conducted following Joanna Briggs Institute guidance on systematic reviews of prevalence studies (PROSPERO ID: CRD42022259048). We performed searches of Medline (Ovid), EMBASE, and Web of Science until October 2021, using a strategy designed by an information specialist. We included studies reporting DR prevalence among diabetic patients in Indigenous and non-Indigenous Australian populations. Two independent reviewers performed quality assessments using a 9-item appraisal tool. Meta-analysis and meta-regression were performed using double arcsine transformation and a random-effects model comparing Indigenous and non-Indigenous subgroups.

RESULTS

Fifteen studies with 8219 participants met criteria for inclusion. The Indigenous subgroup scored lower on the appraisal tool than the non-Indigenous subgroup (mean score 50% vs. 72%, P = 0.04). In the unadjusted meta-analysis, DR prevalence in the Indigenous subgroup (30.2%; 95% confidence interval [CI], 24.9-35.7) did not differ significantly (P = 0.17) from the non-Indigenous subgroup (23.7%; 95% CI, 16.8-31.4). After adjusting for age and quality, DR prevalence was higher in the Indigenous subgroup (P < 0.01), with prevalence ratio point estimates ranging from 1.72 to 2.58, depending on the meta-regression model. For the secondary outcomes, prevalence estimates were higher in the Indigenous subgroup for diabetic macular edema (DME) (8.7% vs. 2.7%, P = 0.02) and vision-threatening DR (VTDR) (8.6% vs. 3.0%, P = 0.03) but not for proliferative DR (2.5% vs. 0.8%, P = 0.07).

CONCLUSIONS

Indigenous studies scored lower for methodological quality, raising the possibility that systematic differences in research practices may be leading to underestimation of disease burden. After adjusting for age and quality, we found a higher DR prevalence in the Indigenous subgroup. This contrasts with a previous review that reported the opposite finding of lower DR prevalence using unadjusted pooled estimates. Future epidemiological work exploring DR burden in Indigenous communities should aim to address methodological weaknesses identified by this review.