1 Clinical characteristics in the 310 subjects included in the study are given in Table 1 at DCCT baseline (1983-1989), EDIC baseline, and at the time of the digital-to-film transition study (EDIC years 14-16). Inclusion and exclusion criteria for the DCCT have been published previously. Twenty DCCT/EDIC centers certified for both film and digital imaging (of the 28 clinical centers) studied 319 subjects with type 1 diabetes at their regular visits 9 subjects (2.8%) were excluded because they had ungradable digital (n = 6) and/or film (n = 5) photography sets in one or both eyes. In addition to examining conventional measures of agreement between digital and film grading results, we were also able to evaluate retrospectively the degree to which DCCT/EDIC primary study outcomes and conclusions might be altered by transitioning between the different imaging media. Therefore, the DCCT/EDIC Research Group undertook a formal due-diligence ancillary study to gauge the effect on retinal outcomes of switching from film to digital photography. Although several cross-sectional studies have reported that digital systems provide results that are similar to the film “gold standard,” most represent single-center experience and some lack a wide range of retinopathy severity. Commercial digital fundus camera systems have markedly improved in quality, have been widely adopted by clinics, and offer substantial convenience and economy compared with film cameras.Ĭhanging retinal imaging methods in the DCCT/EDIC, while perhaps unavoidable, might alter study analysis results and conclusions. 5 - 9 Since the inception of the DCCT in 1983, recording of retinal images, from which DR status and progression are evaluated, has inexorably moved from film to digital. 1 - 3 The EDIC (1994-2016 ), an observational follow-up study of the DCCT cohort, 4 demonstrated that the differences in DR and other microvascular (and macrovascular) outcomes between the former intensive and conventional treatment groups persisted for at least 10 years after the DCCT despite the loss of glycemic separation after the clinical trial ended. The DCCT (1983-1993) demonstrated that intensive therapy aimed at maintaining blood glucose levels as close to normal as possible substantially reduced the risk of development and/or progression of diabetic retinopathy (DR) and other microvascular complications compared with conventional therapy. Long-term multicenter studies such as the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) require consistent measurements of key outcome parameters over time and across clinics, especially when technology evolves during the study. Major conclusions were similar with digital vs film gradings (odds reductions with intensive diabetes therapy for proliferative DR at EDIC years 14 to 16: 65.5% digital vs 64.3% film).Ĭonclusion Digital and film evaluations of DR were comparable for ETDRS severity levels, DCCT/EDIC design outcomes, and major study conclusions, indicating that switching media should not adversely affect ongoing studies. Agreement was 86% to 99% sensitivity, 75% to 98% and specificity, 72% to 99%. For major DR outcomes (≥3-step progression on the ETDRS scale and disease presence at ascending thresholds), digital vs film κ values ranged from 0.69 to 0.96 (“substantial” to “nearly perfect”). Overall, digital grading did not systematically underestimate or overestimate severity (McNemar bias test, P = .14). Results Comparing DR severity, digital vs film yielded a weighted κ of 0.74 for eye level and 0.73 for patient level (“substantial”). For retinopathy outcomes with greater than 10% prevalence, we had 85% or greater power to detect an agreement κ of 0.7 or lower from our target of 0.9. Severity of DR was assessed centrally from film and tonally standardized digital cameras. Methods At 20 clinics from 2007 through 2009, 310 participants with type 1 diabetes with a broad range of DR were imaged, per the Early Treatment Diabetic Retinopathy Study (ETDRS) protocol, with both film and digital cameras. Objective To compare diabetic retinopathy (DR) severity as evaluated by digital and film images in a long-term multicenter study, as the obsolescence of film forced the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study (DCCT/EDIC) to transition to digital after 25 years. Shared Decision Making and Communication.Scientific Discovery and the Future of Medicine. Health Care Economics, Insurance, Payment.Clinical Implications of Basic Neuroscience.Challenges in Clinical Electrocardiography.
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