Optical Coherence Tomography Grading Reproducibility during the Comparison of Age-related Macular Degeneration Treatments Trials

Abstract

OBJECTIVE To report Reading Center reproducibility during grading of Optical Coherence Tomography (OCT, Carl Zeiss Meditec, Dublin, California) images obtained during the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT). DESIGN Prospective clinical trial PARTICIPANTS Independent reading teams reevaluated 270 OCT scans randomly sampled from the first 2 years of CATT enrollment. To assess temporal drift, a cohort of 23 scans submitted during the initial portion of the CATT study was longitudinally followed with serial reproducibility analysis. INTERVENTION CATT readers performed standardized grading on OCT images. A reader team, composed of two independent readers and a Senior Reader, evaluated each scan. Grading included the CATT OCT endpoints of total thickness at the foveal center point and intraretinal fluid, subretinal fluid, and sub-retinal pigment epithelium (RPE) fluid. Independent reading teams masked to the results of initial grading reevaluated scans to determine reproducibility of qualitative grading and measurements. MAIN OUTCOME MEASURES Categorical grading agreement was reported using percent agreement and kappa statistic and measurement agreement was reported using intraclass correlations and paired differences. RESULTS Reading Center teams reproducibly graded intraretinal fluid (percent agreement = 73%, kappa = 0.48, 95% confidence interval or CI 0.38 to 0.58), subretinal fluid (percent agreement = 90%, kappa = 0.80, 95% CI 0.73 to 0.87), and sub-RPE fluid (percent agreement 88%, kappa = 0.75, 95% CI 0.67 to 0.83). For independent Reading Center team measurements of total thickness at the foveal center point, the intraclass correlation was 0.99 (95% CI 0.99 to 0.99, and the mean paired difference between Reading Center teams was −4 micrometers (95% limits of agreement −55 to 47 micrometers). There was no qualitative or quantitative grading drift. CONCLUSIONS The standardized protocols used to evaluate OCT scans from the CATT study were reproducible. The methods used are suitable to monitor OCT imaging data from a large neovascular age related macular degeneration interventional multicenter study.

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