THE PROGRESSION OF RETINOPATHY OVER 2 YEARS - THE PITTSBURGH EPIDEMIOLOGY OF DIABETES COMPLICATIONS (EDC) STUDY

This study examined potential risk factors for the incidence and progr ession of retinopathy in a large representative cohort of childhood on set insulin-dependent diabetic patients. Participants in the Epidemiol ogy of Diabetes Complications (EDC) Study underwent a full clinical ex amination at baseline and again at a 2-year follow-up. Retinopathy sta tus was ascertained using stereo fundus photographs graded according t o the modified Airlie House System. The study population is based on a large cohort of childhood-onset insulin-dependent diabetic patients, seen within 1 year of diagnosis at the Children's Hospital of Pittsbur gh between January 1950 and May 1980. A total of 657 subjects particip ated at baseline (1986-1988), with 80% of eligible survivors taking pa rt in the follow-up examination. This report concerns risk factors ass ociated with the progression of diabetic retinopathy over a 2-year per iod, and the interaction of these factors with the presence of nephrop athy. Analyses showed that baseline diastolic blood pressure was signi ficantly associated with the incidence of any retinopathy, while glyco sylated hemoglobin, baseline severity of retinopathy, serum triglyceri des, and, to a lesser extent, higher levels of low-density lipoprotein (LDL) cholesterol and fibrinogen were associated with the progression of retinopathy. Progression to proliferative retinopathy was related to higher LDL cholesterol, fibrinogen, serum triglycerides, albumin ex cretion rate, and glycosylated hemoglobin (GHb). Risk factors varied w ith the presence of nephropathy. In the absence of nephropathy, GHb wa s a significant predictor of progression, whilst this was not the case in the presence of nephropathy. Multivariate analyses demonstrated th at the incidence of new cases of retinopathy was associated only with baseline diastolic blood pressure, while both the progression of retin opathy and progression to proliferative retinopathy were significantly associated with baseline glycosylated hemoglobin and baseline severit y of retinopathy. These results suggest that the risk factors for the development of retinopathy may differ at various stages of the disease and according to the presence of nephropathy. While blood pressure, e ven within the normal range, may be important in the early stages of r etinopathy, glycemic control remains the most important factor in the long-term development of this complication.