Elsevier

Ophthalmology

Volume 112, Issue 5, May 2005, Pages 799-805
Ophthalmology

Original article
Hyperglycemia, Blood Pressure, and the 9-Year Incidence of Diabetic Retinopathy: The Barbados Eye Studies

https://doi.org/10.1016/j.ophtha.2004.11.054Get rights and content

Objectives

To evaluate factors related to the incidence of diabetic retinopathy (DR) in a population of African descent, after 9 years of follow-up.

Design

Population-based cohort study; 81% participation after 9 years.

Participants

Three hundred twenty-four participants of the Barbados Eye Studies, with diabetes mellitus (DM) at baseline and at risk for developing DR during follow-up.

Methods

Diabetes-related changes were assessed by masked gradings of baseline and follow-up photographs using a standardized system. The 9-year cumulative incidence of DR was based on participants with DM and free of retinopathy at baseline; incidence rates were estimated by the product-limit approach. Cox regression models for discrete-time data were used to evaluate risk factors associated with the 9-year incidence of DR.

Results

Multivariate analyses revealed that older age at DM onset decreased the 9-year risk of DR development; for each 10 years of older age at onset, the risk of DR decreased by 30% (risk ratio [RR], 0.7; 95% confidence interval [CI], 0.56–0.96). The risk of DR doubled among persons with DM duration between 5 and 9 years (RR, 2.1; 95% CI, 1.2–3.6) versus those with shorter durations; it also doubled in those treated with oral medications or insulin at baseline versus those treated with diet only. Antihypertensive treatment halved the risk of DR versus no treatment (RR, 0.5; 95% CI, 0.3–0.9) and high systolic or diastolic blood pressure (BP) increased risk. Thus, DR risk increased by 30% for every 10 mmHg of higher systolic BP at baseline (RR, 1.3; 95% CI, 1.1–1.4) or of BP increase from baseline to the 4-year follow-up (RR, 1.3; 95% CI, 1.1–1.4). Diabetic retinopathy risk similarly increased with each 1% of higher glycosylated hemoglobin level at baseline (RR, 1.3; 95% CI, 1.2–1.5).

Conclusions

The long-term follow-up of persons with DM in this population of African origin, where disease prevalence is high, identified important potentially modifiable risk factors for DR. Findings suggest that efforts to achieve optimal glycemic and BP control may reduce the vision-threatening complications of DM.

Section snippets

Background

The Barbados Eye Studies (1987–2003), funded by the National Eye Institute, are epidemiologic investigations of the prevalence, incidence, and risk factors for major eye diseases, including DR, in a predominantly African-origin population.13, 14, 15 The baseline prevalence study, the Barbados Eye Study (1987–1992), was based on a simple random sample of Barbadian-born citizens, 40–84 years old (4709 persons; 84% participation; 93% black by self-report).13 The surviving cohort was invited for

Results

This report is based on 324 cohort participants with DM at baseline, who were at risk for developing DR during the 9 years of follow-up.12 Their median age was 58 years, and 64% were female. Table 1 presents the 9-year incidence of DR in this group by various baseline features. Incidence rates did not vary by age, gender, and other characteristics presented in the table, except for age of DM onset. Based on the median age of onset, persons diagnosed with DM before 53 years of age were 1.5 times

Discussion

This long-term longitudinal study has identified several factors related to the development of DR in a population of African origin. Such information, which was not previously available, is valuable for understanding the reasons why DR develops, as well as planning strategies for prevention and targeting groups at high risk.

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    Manuscript no. 2004-2.

    Supported by the National Eye Institute, Bethesda, Maryland (grant nos.: EY07625, EY07617).

    See “Appendix.”

    View full text