Identification of independent risk factors for the development of diabetic retinopathy requiring treatment

Introduction: Diabetic retinopathy is screened by fundus photography and screening intervals are defined according to general rules to ensure that vision threatening complications are detected even if the progression of the disease is fast. The resulting superfluous examinations of patients with slow disease progression can be reduced by a more exact decision model that allows an adjustment of the screening interval to each patient’s individual risk profile. This requires an identification of independent risk factors for reaching treatment end points for diabetic retinopathy. Methods: Clinical data from 5365 patients who had undergone 23 324 examinations at the Department of Ophthalmology, Århus University Hospital between Jan 1st 1994 and Dec 31st 2007 were used to identify independent risk factors for progression of treatment requiring retinopathy. Results: The risk of reaching a treatment end point was in both diabetes types independently affected by retinopathy grade and HbA1c. Furthermore, in type 1 diabetic patients the risk of reaching a treatment end point was independently affected by disease duration and by a recommended control interval of less than 3 months, in spite of correction for retinopathy grade and other studied confounders, whereas in type 2 diabetes this risk was affected by increasing age of diagnosis of the disease. Conclusions: Only a subset of known risk factors for development and progression of diabetic retinopathy should be used to construct a decision model for optimizing screening intervals for diabetic retinopathy.