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The Vanderbilt Classification System in the evaluation of diabetic retinopathy patients treated with Alredase
S S Feman1, T C Leonard-Martin, J R Redman
1Department of Ophthalmology and Visual Sciences (Fundus Photo Reading Center), School of Medicine, Vanderbilt University, Nashville, Tennessee, USA.
Background:
The Vanderbilt Classification System is a quantitative method of measuring features detected in diabetic retinopathy photographs. It does not require comparisons to preexisting standard photographs. This is the first report of the application of this system to a large-scale, multiple-medical-center drug trial.
Methods:
This was a prospective, randomized, double-masked, placebo-controlled study that involved 74 medical centers. There were 3,679 out-patients followed for more that 4 years, with some observed for over 9 years. The Vanderbilt Classification System generated patient data for the Early Treatment Diabetic Retinopathy Study (ETDRS) and the Diabetes Control and Complication Trial (DCCT) scales. The deterioration rate was one variable used to assess drug effect. A comprehensive Quality Assurance Program evaluated intergrader and intragrader reliability.
Results:
Target values for reliability and reproducibility were met or exceeded on all measures of agreement between photo readers and over time. Kappa statistics were 0.610 or greater, with most weighted kappa values greater than 0.810. This represents "almost perfect agreement" and compares favorably with previous reports from the ETDRS and DCCT.
Conclusion:
Diabetic retinopathy can be evaluated in a reliable and reproducible manner with the VCS. The VCS is unique in that it produces a quantitative analysis of retinal lesions. Subtle variations that might be influenced by systemic medications can be measured accurately with this technique.