The Karen instruments for measuring quality of nursing care: construct validity and internal consistency.

BACKGROUND Valid and reliable instruments for measuring the quality of care are needed for evaluation and improvement of nursing care. Previously developed and evaluated instruments, the Karen-patient and the Karen-personnel based on Donabedian's Structure-Process-Outcome triad (S-P-O triad) had promising content validity, discriminative power and internal consistency. OBJECTIVE The objective of this study was to further develop the instruments with regard to construct validity and internal consistency. DESIGN AND SETTING This prospective study was carried out in medical and surgical wards at a hospital in Sweden. A total of 95 patients and 120 personnel were included. METHODS The instruments were tested for construct validity by performing factor analyses in two steps and for internal consistency using Cronbach's alpha coefficient. RESULTS The first confirmatory factor analyses, with a pre-determined three-factor solution did not load well according to the S-P-O triad, but the second exploratory factor analysis with a six-factor solution appeared to be more coherent and the distribution of variables seemed to be logical. The reliability, i.e. internal consistency, was good in both factor analyses. CONCLUSIONS The Karen-patient and the Karen-personnel instruments have achieved acceptable levels of construct validity. The internal consistency of the instruments is good. This indicates that the instruments may be suitable to use in clinical practice for measuring the quality of nursing care.