Predicting the risk of diabetic retinopathy in type 2 diabetic patients
Introduction
Diabetes mellitus (DM) is a condition primarily defined by the level of hyperglycemia responsible for microvascular damage (retinopathy, nephropathy and neuropathy). It has been estimated that the global prevalence of diabetes in the year 2000 has been 2.8% (about 171 million of affected people), and projections for 2030 increase this value to 4.4%. Type 2 diabetes accounts for the 85%–95% of all the cases of DM (Wild, Roglic, Green, Sicree, & King, 2004). Diabetic retinopathy (DR), the more frequent diabetic microvascular complication, affects 30%–50% of all diabetic patients and represents the main cause of legal blindness in 20–74-year-old people in the developed countries (Klein, 2007).
The high prevalence and severity of DR suggest the need for screening program able to recognize it as early as possible; this recommendation becomes even more important since DR may be asymptomatic even in its more advanced stages. Current guidelines suggest that patients with type 2 diabetes should have a comprehensive eye examination shortly after the diagnosis because DR is often already present at that time; the result of the first eye check influences the rate of the subsequent checks (American Diabetes Association, 2008a, Swanson, 2005, Williams et al., 2004). The rate of progression is different among diabetic individuals, being more severe in Hispanic than in African Americans or European Americans (Hallman et al., 2005, Tudor et al., 1998). Since these observations were independent of glycemic control and environmental factors, they may be depending on the genetic pattern typical of each ethnic group; moreover, other evidence suggests that DR may be also associated with gene polymorphisms of factors involved in angiogenesis (Janik-Papis et al., 2009). This variability makes the complete adherence to the guidelines difficult to realize, mainly because of the discrepancy among the high number of patients to consult, the very composite interindividual difference and the low possibility to ensure an ophthalmologic examination at that time to each patient.
These problems prompted us to find a method able to quickly identify patients at higher risk to develop DR, to give a priority in the access to the ophthalmologic services and to the consequent appropriate treatments. Aim of this study has been to quantify the individual risk for DR in type 2 diabetic patients and to provide a useful decision-making nomogram to fulfill this challenge.
Section snippets
Patients and methods
Data from diabetic patients followed-up in the Diabetology Unit of “A.O. Spedali Civili Brescia” have been prospectively recorded both for clinical purpose and for outcome studies. The present retrospective analysis on those data includes 8324 diabetic type 2 patients followed up through 1 January 1996–31 December 2007. Inclusion criteria were (a) type 2 DM diagnosis, (b) no presence of DR at the time of the first check and (c) two yearly clinical checks over the follow-up period, performed
Results
Total population studied was made up of 8324 type 2 diabetic patients; 2603 patients were excluded due to insufficient follow-up and 687 due to presence of DR already at the baseline check. The final analyses was conducted on 5034 patients, whose baseline characteristics compared with those of patients with insufficient follow-up are reported in Table 1. During the follow-up, DR occurred in 569 patients (11%) after a median time of 1.2 years (IQ=0.2; IIIQ=3.0). Compared to those without
Discussion
Diabetic retinopathy is an important cause of visual impairment; and thus, the arrangement of appropriate screening test becomes crucial to avoid any delay in its diagnosis and treatment. Nevertheless, a large percentage of diabetic individuals continue to receive a inadequate retinopathy screening. One of the main motivations for screening for DR is both the established efficacy of the early treatment in preventing vision loss and the progressive increase in the number of diabetic patients in
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