Data collection on retinopathy as a public health tool: The Hubble telescope equivalent of looking back in time
Introduction
Diabetic retinopathy (DR) is an important complication of diabetes which causes considerable morbidity and also associated with significant increase in mortality of those affected. At an individual level, the presence of retinopathy is best predicted, although far from perfectly, by the duration of diabetes and the overall glycemic exposure of the individual in the previous years (Klein et al., 1994, Nathan et al., 1986, Wong et al., 2008, Nordwall et al., 2015). By contrast to the relatively poor predictability at an individual level, investigators have previously demonstrated a strong linear relationship between duration of diabetes and prevalence of retinopathy at a population level, e.g., in a Wisconsin and a Western Australian population (Harris, Klein, Welborn, & Knuiman, 1992). The slope of such relationship between prevalence of retinopathy and duration of diabetes is a measure of the rate of retinopathy development per unit time for that population. We used patient information stored in our electronic database to test the hypothesis that the rate of retinopathy development calculated in this manner can be used to estimate the prior glycemic control of the population.
Our electronic database collected information including retinopathy status, duration of diabetes and glycemic control of our patients over more than two decades (McGill, Molyneaux, Yue, & Turtle, 1993). We used these data to construct the linear relationship between duration of diabetes and prevalence of retinopathy. As duration of diabetes is already accounted for in the x-axis, the slope of the linear regression should correlate well with the prior glycemic control of the individual group being examined. The implication being that, if this assumption is proven, cross-sectional data of retinopathy prevalence at various duration of diabetes in a defined population can be used to retrospectively assess the adequacy of glycemic control of that population in the preceding years. Health Maintenance Organizations and some community screening programs could have information on the status of retinopathy and duration of diabetes of their participants but not serial measurements of HbA1c (Scanlon, Aldington, & Stratton, 2014). Their data could be analyzed by our method to serve as an indirect measurement of the average glycemic control of their patients in the preceding 1–2 decades. By examining data of patients with defined criteria (e.g., according to their ethnicity or age of diabetes onset), the prior glycemic control of specifically defined groups of diabetic patients can be compared. Our method which only requires cross-sectional and retrospective data could be a simple but useful public health tool.
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Methods
The findings of this study were derived from a total cohort of 9281 patients with T2DM who had information collected prospectively during clinical consultations over a period of approximately two to three decades. For this study, the following data from each patient were retrieved from our electronic database: retinopathy status, HbA1c, ethnicity, date of diabetes diagnosis, date of last consultation with documented retinopathy data, socio-economic status and fluency in English. Retinopathy was
Results
Diabetes duration and updated HbA1c were relatively poor predictors for the presence of retinopathy in individuals. These two factors only accounted for 13.8% of the variance for the presence of retinopathy in individuals in the total cohort of 9281 patients. Other factors examined including age of diagnosis, blood pressure, smoking status and gender did not add to the prediction of retinopathy in individuals. By contrast, as shown in Fig. 1A and B, the relationship between duration of diabetes
Discussion
It is well accepted that glycemic control and duration of diabetes are the major determinants for the presence of DR, but their predictive power for individual patients is only modest (Nathan, 2014, Group TDCaCTR, 1995). In our cohort these two factors only account for 13.8% of the variance of retinopathy, underlying the importance of routine screening in clinical practice. A less appreciated but the fundamental basis of our study is that, in contrast to the situation for individuals, duration
References (16)
- et al.
Microvascular disease and risk of cardiovascular events among individuals with type 2 diabetes: A population-level cohort study
The Lancet Diabetes & Endocrinology
(2016) The relationship of glycemic exposure (HbA1c) to the risk of development and progression of retinopathy in the diabetes control and complications trial
Diabetes
(1995)- et al.
Onset of NIDDM occurs at least 4–7 yr before clinical diagnosis
Diabetes Care
(1992) - et al.
The Wisconsin Epidemiologic Study of Diabetic Retinopathy. XIV. Ten-year incidence and progression of diabetic retinopathy
Archives of Ophthalmology
(1994) - et al.
Diabetic retinopathy predicts all-cause mortality and cardiovascular events in both type 1 and 2 diabetes
Meta-Analysis of Observational Studies
(2011) - et al.
Temporal validation of the UKPDS outcomes model using 10-year posttrial monitoring data
Diabetes Care
(2013) - et al.
A single visit diabetes complication assessment service: A complement to diabetes management at the primary care level
Diabetic Medicine
(1993) The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications study at 30 years: Overview
Diabetes Care
(2014)
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Conflicts of interest: The authors have no relevant conflicts of interest to declare.