April 2009
Volume 50, Issue 13
ARVO Annual Meeting Abstract  |   April 2009
Performance of Confirmation as a Strategy to Retain Acceptable Specificity and Sensitivity When Monitoring Glaucoma Over Multiple Visits
Author Affiliations & Notes
  • W. J. Feuer
    Biostatistics, Bascom Palmer, Miami, Florida
  • M. Durbin
    R & D, Carl Zeiss Meditec, Inc, Dublin, California
  • Footnotes
    Commercial Relationships  W.J. Feuer, None; M. Durbin, Carl Zeiss Meditec, Inc, E.
  • Footnotes
    Support  RPB unrestricted grant to the department of ophthalmology, NIH Center Grant P30 EY014801
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 2250. doi:
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      W. J. Feuer, M. Durbin; Performance of Confirmation as a Strategy to Retain Acceptable Specificity and Sensitivity When Monitoring Glaucoma Over Multiple Visits. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2250.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : Statistical methods to detect reduction in RNFL thickness resulting from glaucomatous progression may suffer from reduced specificity due to alpha error inflation upon repeat testing over long follow-up. The purpose of this study is to evaluate the performance of and compare two strategies for assessing progression: linear regression and confirmed change from baseline.

Methods: : Data representing 15 semi-annual visits was generated (n=10,000) from a random normal distribution with variability based on that reported for the Average RNFL thickness measurement of the Cirrus HD-OCTTM. In addition, a slow progressive thinning (1.4 µm per year) was applied on top of this to simulate a population of progressors. The simulated, accumulating data was fit with linear regression at each visit, starting with visit 4, until statistical significance (p<0.05) occurred or the 15th visit was reached. Additionally, at each visit, a confirmed change from baseline analysis was performed between the two most recent visits and the two baseline visits (4 separate comparisons). A comparison was considered statistically significant if it exceeded the 95% confidence limits on the difference between two Cirrus average thickness measurements based on an in-house reproducibility study. If three of four comparisons met this criterion, then change from baseline was confirmed. This procedure was similarly repeated for each visit until a change was confirmed or the 15th visit was reached. Sensitivity and specificity of two methods was evaluated.

Results: : The figures display how sensitivity and specificity change upon repeat testing for each method.

Conclusions: : Compared to linear regression, the confirmed change from baseline strategy keeps specificity high across multiple visits. Sensitivity is reduced with confirmed change, but improves with additional visits.

Keywords: imaging/image analysis: clinical • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • optic disc 

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