The Port-A-Cath Application and Care Knowledge Scale (PACKS) for nurses: Development and initial validation with Rasch analysis

Abstract

Purpose: This study aimed to develop a Port-A-Cath Application and Care Knowledge Scale (PACKS) for nurses and examine its initial psychometric properties. Method: This was a methodological study. The initial 30 items of the PACKS included two subscales with items generated from a literature review, expert validity, and face validation. A questionnaire survey was then completed by clinical nurses (n =377) from three hospitals in Taiwan. Rasch analysis was used to test whether each PACKS subscale was unidimensional and whether all items in the same subscale fit with their constructs. Results: The application knowledge PACKS subscale demonstrated evidence of unidimensionality with acceptable item fit according to the Rasch model (infit mean square [MnSq] = 0.91-1.08; outfit MnSq = 0.66-1.15). Similarly, the care knowledge PACKS subscale demonstrated evidence of unidimensionality with acceptable item fit except (infit MnSq = 0.87-1.16; outfit MnSq = 0.77-1.28) for the fifth item (outfit MnSq = 1.77). After removing the fifth item, all the remaining items had acceptable infit and outfit MnSq. However, several items displayed differential item functioning (DIF) across gender, which could have been caused by the imbalanced gender distribution in this study. Conclusions: The PACKS is a reliable and valid instrument which clinical staff and researchers can use to evaluate nurses’ knowledge on Port-A-Cath application and care.