DR study: 25 year results

Although there is a relatively high rate of diabetic retinopathy (DR) progressing to proliferative diabetic retinopathy (PDR), the level of PDR care available has improved, according to 25-year results of the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR), published in the November issue of Ophthalmology.

Ronald Klein, MD, MPH of the Department of Ophthalmology and Visual Sciences at the University of Wisconsin School of Medicine and Public Health in Madison, US and colleagues conducted the population-based study of diabetic subjects (n=955) living in the Wisconsin area of the US. Participants took insulin, and had been diagnosed with Type 1 diabetes before 30 years of age. Baseline examinations were conducted between 1980 and 1982; follow-up visits were conducted at four, 10, 14 and 25 years, with 520 subjects completing the final follow-up.

At the final follow-up point, the rate of DR improvement was 18%; the cumulative rate of DR progression was 83%, and the rate of progression of DR to PDR was 42%. Overall, factors found to influence (increase) DR progression were: severity of DR (less severe), gender (male), glycosylated haemoglobin level (high or increasing) and diastolic blood pressure (increasing before the four-year follow-up visit). Factors increasing PDR incidence were high body mass index (BMI) at baseline, high systolic blood pressure and glycosylated haemoglobin levels (particularly with an increase before the four year follow-up point), and proteinuria. The more recent the diabetes diagnosis, the lower the prevalence of PDR: this held true independently of the other PDR influential factors.

The researchers concluded that good glycaemic control reduced the risk of DR progression and, although the progression of DR across the study period was high, a more recent diabetes diagnosis decreased the prevalence of PDR, possibly due to an improvement in care over the study period.