Relative Importance and Contribiton of Risk Factors for Diabetic Retinopathy and Macular Edema

Purpose: This study determined the relative importance of risk factors for Diabetic Retinopathy (DR) and Diabetic Macular Edema (DME) and assessed their independent and joint contributions. Methods: A prospective study of patients with type 2 diabetes was conducted in a tertiary eye hospital in Melbourne, Australia. Patients underwent a comprehensive eye examination and completed standardized administered questionnaires. Blood samples were assessed for glycated haemoglobin (HbA1c); fasting blood glucose; and serum lipids. Dilated fundus photographs were obtained and graded for DR and DME. The relative importance of the risk factors was determined by the independent and common variance explained in DR and DME using Commonality analysis. Results: A total of 497 patients with type 2 diabetes were included in this analysis. The key risk factors accounted for 44.6% and 19.5% of total variances in DR and DME, respectively. The most important risk factor for any DR was duration of diabetes (16.5% of total explained variance), followed by insulin use (13.1%), HbA1c (8.5%), age (3.7%) and gender (2.8%). The most important risk factor for any DME was HbA1c (9.45%); followed by age (5.75%); duration of diabetes (3.92%) and systolic blood pressure (SBP) (0.36%). Sixty-one percent of the total explained variance in DR was due to common variance among these risk factors, compared to only 31% of the in DME. Conclusion: The total, independent and joint contributions of the key risk factors for DR and DME differ in patients with type 2 diabetes, which suggest that may require specific prevention and intervention strategies for these two diabetic complications.