Validation of the instrument “Complexity of Nursing Care”—A mixed‐methods study

AIMS: This study aimed to psychometrically test the instrument “Complexity of Nursing Care” and to broaden the understanding of the instrument's psychometrics and applicability. DESIGN: Embedded mixed‐methods design. METHODS: We performed a cross‐sectional study assessing all stationary patients of five Swiss hospitals daily for up to 5 days with the instrument “Complexity of Nursing Care” over a 1–month period in 2015. The scale's psychometrics were analysed using partial least square structural equation modelling. In the qualitative study section, we completed 12 case studies and analysed them case‐wise and across cases. Quantitative and qualitative results were synthesized in tables. RESULTS: Structural equation modelling confirmed a reflective‐formative second‐order model of the instrument with good psychometric properties leading to a formula for the calculation of a complexity score. Qualitative results evolved descriptions of low and high extent of complexity. Narrative considerations of two raters deepened the understanding of the inter‐rater reliability.