Incidence and Progression of Diabetic Retinopathy During 17 Years of a Population-Based Screening Program

OBJECTIVEdTo estimate the incidence of diabetic retinopathy in relation to retinopathy grade at first examination and other prognostic characteristics. RESEARCH DESIGN AND METHODSdThis was a dynamic cohort study of 20,686 people with type 2 diabetes who had annual retinal photography up to 14 times between 1990 and 2006. Cumulative and annual incidence rates were estimated using life tables, and risk factors for progression were identified using Cox regression analysis. RESULTSdOf 20,686 patients without proliferative diabetic retinopathy (PDR) or sight-threatening maculopathy at their first retinal examination (baseline), 16,444 (79%) did not have retinopathy, 3,632 (18%) had nonproliferative retinopathy, and 610 (2.9%) had pre-proliferative retinopathy. After 5 years, few patients without retinopathy at baseline developed preproliferative retinopathy (cumulative incidence 4.0%), sight-threatening maculopathy (0.59%), or PDR (0.68%); after 10 years, the respective cumulative incidences were 16.4, 1.2, and 1.5%. Among those with nonproliferative (background) retinopathy at baseline, after 1 year 23 % developed preproliferative retinopathy, 5.2 % developedmaculopathy, and 6.1%developed PDR; after 10 years, the respective cumulative incidences were 53, 9.6, and 11%. Patients wit