Intra and interobserver agreement in the classification of fundus autofluorescence patterns in geographic atrophy secondary to age-related macular degeneration.

BACKGROUND: To describe the intra and interobserver agreement in the evaluation of fundus autofluorescence patterns in geographic atrophy secondary to age-related macular degeneration.
METHODS: A consecutive series of patients with geographic atrophy and fundus autofluorescence images of a minimum acceptable quality for grading were included. Four observers with experience in the evaluation of autofluorescence images 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 statistic and 95% confidence intervals, together with percentages of agreement, were used to analyze the results.
RESULTS: The final sample included 69 eyes of 49 patients. Intraobserver agreement ranged from substantial to almost perfect (kappa between 0.51 and 0.83), while interobserver results ranged from poor to substantial (corresponding to kappa between 0.30 and 0.62). The use of more simple classifications improved reproducibility.
CONCLUSIONS: Although intraobserver reproducibility was high, interobserver agreement was variable. Clear descriptions and a uniform set of criteria to classify these patients are needed if fundus autofluorescence imaging is used to evaluate patients with geographic atrophy.