The Positive Aspects of Caregiving Scale can be shortened to six items: application of item response theory

Abstract

Objective For nearly two decades, with one exception, researchers have used the Positive Aspects of Caregiving Scale (PACS) without a close examination of how the items behave. This study examined PACS’ measurement model and item response characteristics, including differential item functioning (DIF) by race. Methods Item response theory was used to analyze the baseline data of the Resources for Enhancing Alzheimer’s Caregiver Health (REACH) I trial (N = 1229). Bifactor confirmatory models were estimated to assess dimensionality, and whether the items behaved differently in African Americans and Hispanics, with Whites serving as the comparison, were examined using the multiple-indicators multiple-causes model. Results For both 9- and 11-item versions, 1-factor and bifactor solutions supported a unidimensional structure. However, the items performed generally poorly in differentiating levels of the latent construct, especially between moderate and high true scores. Additionally, five items were found to have DIF, which were unrelated to relationship differences among racial groups. While African Americans and Hispanics reported higher positive gains than Whites, their differences were accentuated by the DIF items as a whole. A 6-item version called PACS-II was created by removing the DIF items. Besides reducing estimated racial differences, PACS-II removed race-based heterogeneity of variance that was evidenced in the original, longer versions. Conclusions Being free of racial bias, PACS-II is preferred over the original versions, though the ceiling effect of measurement (prevalence of extreme scores on the high end) remains to be an issue for improvement.