Abstract
Purpose:
Understanding the population-level risk factor contribution to diabetic retinopathy (DR) is critical for the effective allocation of preventative strategies. We quantified the population attributable risks (PARs) of risk factors attributed to DR in people with type 2 diabetes.
Methods:
We used data from a cross-sectional study of patients with diabetes attending a tertiary eye hospital in Melbourne, Australia. Patients underwent a comprehensive eye examination and completed standardized interview-administered questionnaires. Blood samples were assessed for HbA1c, fasting blood glucose, and serum lipids. Dilated fundus photographs (disc- and macula-centred) were obtained and graded for the presence and severity of DR. The multivariable adjusted population attributable risk (PAR) was calculated from individuals’ data using logistic regression and considers an average of all possible sequences for removal of risk factors in the community.
Results:
Among 464 patients with type 2 diabetes, 59.5% (n=276) had any DR. The significant adjusted odds ratios (ORs) and 95% for DR were: younger (<65 years) age (3.2, 95% confidence interval [CI]: 2.0-5.2), male gender (2.2, 95% CI: 1.3-3.6), longer duration of diabetes (>15 years) (4.5, 95% CI: 2.7-7.7), poor glycemic control (HbA1c >7.0%) (2.4, 95% CI: 1.4-3.9), insulin use (2.8, 95% CI: 1.6-5.1) and not-taking hypertension medication (1.8, 95% CI: 1.1-3.0), respectively. The adjusted total PAR (95% CI) for modifiable risk factors (poor glycemic control, insulin use and medication for hypertension) was 24.8% (14.9-34.2%). Of these, poor glycemic control had the highest impact with PAR (95% CI) of 10.2% (4.0-16.4%), followed by not-taking hypertension medication 6.5% (95% CI: 1.1-11.2%) and insulin use 5.5% (2.5-8.6%). The adjusted total PAR (95% CI) for non-modifiable risk factors (age, gender and duration of diabetes) was 32.0% (23.4 -40.1%). Duration of diabetes, male gender, and younger age had similar impact on DR with PARs (95% CI) of 10.4% (6.6-14.2%), 8.9% [3.1-14.8%]), and 8.9% (5.3-12.5%), respectively.
Conclusions:
Only one quarter of DR cases in the population can be prevented by glycemic control, and adherence to medication for hypertension.