The Health of the Nation Outcome Scales: validating factorial structure and invariance across two health services.

Abstract

The Health of the Nation Outcome Scale (HoNOS) was developed in the mid-1990s as an inclusive and comprehensive instrument to measure patient outcomes in four main factors: behaviour, impairment, symptoms and social problems. This paper attempts to investigate whether similar health services rate the HoNOS with equivalent psychometric calibration. The purpose of this study was to test for invariant construct interpretation of the instrument across two equivalent health services, using simultaneous confirmatory factor analysis. Although the four-factor model of the HoNOS was confirmed, structural non-invariance occurred, casting doubt on the equivalent interpretability and generalisability of the instrument across similar heath services. Over-inclusiveness, lack of specificity and questionable independence of observations may have contributed to the non-invariant factor structure between the two health services. Such results shed some doubt on the ability of the HoNOS and like observational instruments to provide equivalent comparisons between health services.