May 2008
Volume 49, Issue 13
ARVO Annual Meeting Abstract  |   May 2008
Psychometric Properties of the Glaucoma Treatment Compliance Assessment Tool
Author Affiliations & Notes
  • T. M. McClure
    Legacy Health System, Devers Eye Institute, Portland, Oregon
  • I. L. Swanson
    Legacy Health System, Devers Eye Institute, Portland, Oregon
  • W. E. Lambert
    Public Health and Preventive Medicine, Oregon Health and Science University, Portland, Oregon
  • G. A. Cioffi
    Legacy Health System, Devers Eye Institute, Portland, Oregon
  • S. L. Mansberger
    Legacy Health System, Devers Eye Institute, Portland, Oregon
  • Footnotes
    Commercial Relationships  T.M. McClure, None; I.L. Swanson, None; W.E. Lambert, None; G.A. Cioffi, Pfizer, R; Alcon, R; Allergan, R; S.L. Mansberger, Alcon, R; Allergan, R; Pfizer, R.
  • Footnotes
    Support  American Glaucoma Society (SLM); Alcon (SLM); NEI 5K23EY015501-01 (SLM)
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 5459. doi:
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    • Get Citation

      T. M. McClure, I. L. Swanson, W. E. Lambert, G. A. Cioffi, S. L. Mansberger; Psychometric Properties of the Glaucoma Treatment Compliance Assessment Tool. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5459. doi:

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

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Purpose: : We created the Glaucoma Treatment Compliance Assessment Tool (GTCAT) to determine the factors related to compliance with ocular hypotensive medications. We were interested in the construct validity and reproducibility.

Methods: : We enrolled 60 consecutive glaucoma patients from a tertiary practice into this cross-sectional survey. We determined construct validity using Principal Components Analysis (PCA), internal consistency reliability, and frequency analysis of floor and ceiling effects. We used paired t-tests, Pearson’s correlations, chi-square, McNemar’s test, and Intraclass Correlation Coefficients, as applicable, to determine reproducibility.

Results: : PCA showed significant factor loadings on 8 components and 7 were consistent with the constructs of the Health Belief Model (severity, benefits, self-efficacy, barriers, knowledge, susceptibility, and cues-to-action). Of these 7 components, 4 (Severity, Benefits, Self-Efficacy and Barriers) showed acceptable internal consistency reliability (Cronbach’s α > 0.70); knowledge showed borderline reliability (α=0.64); and susceptibility had poor reliability (α = 0.38). We could not determine internal consistency for cues-to-action since it only included 1 question. We excluded 2 (8 %) out of 25 questions from the reproducibility analysis because of ceiling effects. Reproducibility was 91% (21/23). Intraclass Correlation Coefficients were excellent (r≥0.60) for 15 (75%) questions and acceptable (r≥0.40) for 18 (90%) out of 20 questions.

Conclusions: : These preliminary data suggest that the GTCAT has good construct validity and reproducibility. Removing questions with poor reliability or ceiling effects will result in a shorter questionnaire. We need to evaluate content validity and predictive validity prior to clinical implementation.

Keywords: clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials 

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