Purchase this article with an account.
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.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
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.
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.
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).
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.
This PDF is available to Subscribers Only