Blindness in a 25-Year Follow-up of a Population-Based Cohort of Danish Type 1 Diabetic Patients
Presented at: Association for Research in Vision and Ophthalmology Annual Meeting, April–May 2008, Fort Lauderdale, Florida.
Received 7 November 2008; received in revised form 23 March 2009; accepted 23 April 2009. published online 10 September 2009.
Purpose
To assess the long-term incidence of blindness and to evaluate risk factors for blindness in a population-based cohort of type 1 diabetic patients.
Design
Retrospective cohort study.
Participants
A population-based cohort of 573 type 1 diabetic patients, all of whom participated in a clinical ophthalmologic examination in 1981 and 1982 and were followed up for 25 years.
Methods
At the baseline examination in 1981 and 1982, visual acuity, level of retinopathy, maculopathy, hemoglobin A1 (HbA1), proteinuria, smoking habits, and blood pressure were evaluated and related to the subsequent development of blindness. Blindness was defined as present in patients who were registered as members of the Danish Association of the Blind between baseline and January 2007. The Danish Association of the Blind is a voluntary organization open for all patients with a best-corrected visual acuity in the best eye of ≤6/60 (20/200) or with complications (i.e., visual fields <10°) subjectively leading to a best-corrected visual acuity in the best eye of ≤6/60 (20/200).
Main Outcome Measures
Evaluation of 25-year incidence of blindness, predictors for blindness, and gender-specific incidence rates for blindness.
Results
The 25-year cumulative crude incidence of blindness was 7.5% (men, 8.0%; women, 6.8%; P = 0.61), corresponding to a mortality-adjusted cumulative incidence of blindness of 9.5% (95% confidence interval [CI], 7.1%–12.0%) and an overall incidence rate of blindness of 4.11 per 1000 person-years (95% CI, 3.03–5.59 per 1000 person-years). Blindness was predicted by HbA1 and maculopathy at baseline. The odds ratio of blindness during follow-up was 1.69 (95% CI, 1.01–2.84) for a 1% increase in baseline HbA1 and was 6.18 (95% CI, 1.18–32.47) and 8.61 (95% CI, 2.54–29.23) for patients with maculopathy in combination with nonproliferative retinopathy and proliferative retinopathy, respectively. Age and duration at baseline, gender, proteinuria, smoking, systolic and diastolic blood pressure, and visual acuity at baseline were not associated with the development of blindness. Mortality was higher in patients who had become blind (61.0% vs. 42.1%; P = 0.02).
Conclusions
Blindness is still a common complication in type 1 diabetes. Glycemic regulation and the presence of maculopathy are important risk factors for the development of blindness.
Financial Disclosure(s)
The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Available online: September 10, 2009.
1Department of Ophthalmology, Odense University Hospital, Odense, Denmark
2Center for National Clinical Databases South, Odense University Hospital, Odense, Denmark
3Department of Ophthalmology, Odense University Hospital, Odense, Denmark
Correspondence: Jakob Grauslund, MD, Department of Ophthalmology, Odense University Hospital, Sdr. Boulevard 29, DK-5000 Odense C, Denmark
Manuscript no. 2008-1324.
Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Supported by the Velux Foundation, Copenhagen, Denmark; Danish Eye Health Society, Copenhagen, Denmark; Sehested Hansen's Foundation, Copenhagen, Denmark; the Danish Diabetes Association, Odense, Denmark; the Synoptik Foundation, Copenhagen, Denmark; The A.P. Møller Foundation for the Advancement of Medical Science, Copenhagen, Denmark; Karen Svankjær Yde's Foundation, Copenhagen, Denmark; the Legacy of Alice and Jørgen A. Rasmussen, Nærum, Denmark; and the Institute of Clinical Research at University of Southern Denmark, Odense, Denmark. The funding organizations had no role in the design or conduct of this research.
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