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Marc Biarnes, Jordi Mones, Fabio M. Trindade; Reproducibility of Fundus Autofluorescence Patterns in Geographic Atrophy Secondary to Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6532.
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Geographic atrophy (GA) is the advanced form of dry age-related macular degeneration. It represents one third of the cases of late disease, is responsible of up to 20% of cases of severe visual loss and currently lacks effective treatment. A better knowledge of its pathogenesis and the factors that drive its progression are mandatory for development of rational therapies. Together with the status of the fellow eye, the patterns of hyperautofluorescence in non-atrophic retina seen on fundus autofluorescence (FAF) are the only known risk factors associated with the progression of atrophy. However, the classification of these patterns is complex since it involves up to 10 categories, which may be collapsed into reduced, more simple ones. The purpose of this study is to describe the intra and interobserver agreement in the evaluation of FAF patterns in GA and to evaluate if the use of more simple categories improves reproducibility.
A consecutive series of patients with GA and FAF images of a minimum acceptable quality for grading were included. Four observers with experience in the evaluation of FAF independently classified the randomly presented series of images on two occasions, at least 1 month apart from each other (intraobserver analysis). The second determination of each observer was used for evaluation of interobserver agreement. The kappa (Κ) statistic and 95% confidence intervals, together with percentages of agreement, were used to analyze the results.
The final sample included 69 eyes of 49 patients: 32 females (65.3%), with a median of 80 years old (range, 50 to 94), and all were Caucasian. Intraobserver agreement ranged from substantial to almost perfect (Κ 0.51-0.83), while interobserver results ranged from poor to substantial (Κ 0.30-0.62). The use of more simple classifications improved reproducibility. The results did not change when the analysis was restricted to only one randomly chosen eye from each patient.
Although intraobserver reproducibility was high, interobserver agreement was variable even among clinicians with experience in the evaluation of FAF images. Clear descriptions and a uniform set of criteria to classify these patients are required when FAF imaging is used in natural history studies or clinical trials in GA. Otherwise, the role of lipofuscin in atrophy progression and the potential impact of these seemingly different phenotypes in genetic studies may be underestimated.
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