Assessing Progress in Retinopathy Outcomes in Type 1 Diabetes

Comparing findings from the Wisconsin Diabetes Registry Study and the Wisconsin Epidemiologic Study of Diabetic Retinopathy

  1. Karen J. Cruickshanks, PHD1,3
  1. 1Department of Population Health Sciences School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
  2. 2Department of Biostatistics and Medical Informatics School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
  3. 3Department of Ophthalmology and Visual Sciences School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
  1. Corresponding author: Mari Palta, mpalta{at}wisc.edu.

Abstract

OBJECTIVE The Wisconsin Diabetes Registry Study (WDRS) cohort consisted of patients diagnosed with type 1 diabetes in the same geographic region as, but 8–34 years later than the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) cohort, providing a unique opportunity to assess changes in complications. We estimated the current prevalence and severity of diabetic retinopathy at 20 years of diabetes duration, compared these between eras, and evaluated the influence of diabetes management.

RESEARCH DESIGN AND METHODS Twenty-year examinations, including fundus photographs, were completed on 305 WDRS subjects during 2007–2011. A subgroup of the WESDR cohort participated in one of four study visits during 1980–1996, at similar diabetes duration (n = 583). Adjusted ordinal logistic regression with three retinopathy severity categories was used to estimate odds ratios (ORs) of more severe retinopathy with diagnosis during an earlier era.

RESULTS Mean hemoglobin A1c (HbA1c) was lower in WDRS than in WESDR (8.0% vs. 9.3% [P < 0.001], and 93% vs. 21% [P < 0.001]) used ≥3 daily insulin injections or an insulin pump. In WDRS, 18% had vision-threatening levels of retinopathy vs. 43% in WESDR. The adjusted OR of more severe retinopathy in the earlier era (OR 3.0, 95% [CI 2.2–4.0]) was reduced by including 20-year HbA1c in the model (OR 2.2 [1.6–3.0]).

CONCLUSIONS Retinopathy severity at a diabetes duration of 20 years is lower in the more recent era of type 1 diabetes. Updated projections should be used when informing newly diagnosed individuals of prognosis and for health care cost assessments. Current glycemic control explained a limited amount of the difference.

  • Received May 4, 2012.
  • Accepted August 29, 2012.

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