Aim: To describe a decade long telemedicine screening for diabetic retinopathy (DR) in the metropolitan area of Padova (North-East Italy) and to report about prevalence/incidence of DR and maculopathy, rate of progression to STDR and optimal screening interval in patients with no DR at first examination.
Methods: Observational, longitudinal, cohort study; 9347 patients with Type 1 and Type 2 diabetes mellitus (DM) underwent 17,344 fundus exams (three-45° color photos per eye) in two diabetes clinics and were graded in the Reading Centre, by certified personnel. The incidence of STDR, progression of maculopathy and risk factors were evaluated by log Rank test (Kaplan-Meier method). A receiver operating curve was used to determine the optimal screening interval in patients who at the first examination had no DR.
Results: The overall prevalence of DR was 27.6%:12.5% mild non proliferative (NPDR), 11.3% moderate NPDR, 2.9% severe NPDR and 0.9% proliferative (PDR). The overall prevalence of maculopathy was 5.7%: 2.8% mild, 2.2% moderate, and 0.7% severe maculopathy. The 10-year incidence of STDR was: 0.6% in no DR, 5.5% in mild NPDR and 21.1% in moderate NPDR at first examination. The 10-year incidence of maculopathy was: 2.1% mild, 1.7% moderate and 0.2% severe. The incidence of STDR in patients with type 1 and type 2 DM and duration>10years was 8.21% and 8.15%;in type 1 DM with duration <10years was 5.5% and in type 2 DM and duration <10years was 1.91%.In patients with no DR at first screening, the best (sensitivity-specificity) follow-up interval is 2.5years.
Conclusions: Screening every 2.5-year in patients without DR at the first examination seems to be adequate. Duration of disease is a relevant risk factor for progression to STDR, however patients with type 1 DM and duration <10years have greater incidence of STDR than patients with type 2 DM and similar disease duration. Epidemiologic data from this decade-long screening program in the North East of Italy may serve for implementing a national screening program.
Keywords: Diabetic maculopathy; Diabetic retinopathy screening; Epidemiology; Sight threatening diabetic retinopathy; Telemedicine.
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