Developing and Validating a Knowledge Questionnaire of Blood Sampling via Central Vascular Access Devices.

Central vascular access devices (CVADs) have become an important focus for safe practice in some patients. The aim of this study was to develop a reliable and valid knowledge questionnaire of blood sampling via CVADs for registered nurses by using both classical test theory (CTT) and Rasch analysis. A cross-sectional study was conducted, and the questionnaire was completed by 445 participants. CTT and Rasch analysis were used to measure the psychometric properties of the questionnaire. The final questionnaire consisted of 23 items. CTT analysis revealed acceptable internal reliability with Cronbach's alpha of 0.825 and content validity index (I-CVI = 0.99, S-CVI/UA = 0.925). Rasch analysis was conducted using a dichotomous scale, and the final 23-item questionnaire is unidimensional. The person reliability index was 0.69 with an item reliability index of 0.97. The test-retest reliability was excellent, with an intraclass correlation coefficient of 0.964. This questionnaire demonstrated a unidimensional structure and good psychological properties and was clinically meaningful for registered nurses to test their knowledge of blood sampling via CVADs. The findings represent a useful beginning for further analysis of the questionnaire in larger samples internationally.