September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Comparing the Psychometric Properties of the Original and Short Versions of the Glaucoma Treatment Compliance Assessment Tool
Author Affiliations & Notes
  • Gordon T. Barker
    Devers Eye Institute, Portland, Oregon, United States
  • Steven L Mansberger
    Devers Eye Institute, Portland, Oregon, United States
  • Footnotes
    Commercial Relationships   Gordon Barker, None; Steven Mansberger, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 5555. doi:
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      Gordon T. Barker, Steven L Mansberger; Comparing the Psychometric Properties of the Original and Short Versions of the Glaucoma Treatment Compliance Assessment Tool. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5555.

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

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Abstract

Purpose : To compare the psychometric properties of a reduced (22 statements) to a long version (47 statements) of the Glaucoma Treatment Compliance Assessment Tool (GTCAT), which is based on the organizational structure of the Health Belief Model.

Methods : We created a reduced GTCAT by removing statements that: 1) did not appear in either the final Principal Components Analysis (PCA) model and 2) did not have a univariate association with adherence; or 3) were highly correlated with a correlation coefficient of .60 or higher with one another. To verify we did not remove key statements, we used PCA on the 25 removed or remaining statements to verify a stable organizational structure and used univariate analysis to determine if we removed a potentially predictive statement. Last, we assessed the construct validity of the remaining statements using PCA and assessed their predictive validity using univariate and multivariate analysis.

Results : Of the original 47 GTCAT statements, we removed 22 because they did not appear in either the PCA analysis or the univariate regression analysis. We removed an additional 3 statements due to high intercorrelation (r = .76-.80). PCA of the 25 excluded statements resulted in no components extracted, and univariate regression indicated no predictive statements. As a whole the removed statements were not predictive (R2=.035, p = .26) of adherence. Clinical acumen suggested re-inclusion of 4 statements with alternate wording. PCA of the remaining 22 items resulted in the extraction of 5 components (knowledge, susceptibility, cues to action, self-efficacy, barriers). Multiple regression showed 6 statements associated with higher adherence (adjusted R2 = 0.27, p<.001), and as a whole the GTCAT-S predicted adherence (R2= .167, p = .01).

Conclusions : A reduced GTCAT maintained an organizational structure consistent with the Health Belief Model and high predictive ability. Future glaucoma medication adherence studies can use the reduced model to determine whether a change in health behavior as measured by the GTCAT is associated with a change in adherence.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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