Psychometric analysis with the Rasch model of the Health of the Nation Outcome Scales (HoNOS) in Uruguayan population Análisis psicométrico con el modelo de Rasch de la escala Health of the Nation Outcome Scales (HoNOS) en población uruguaya

Abstract

The aim of the study was to analyze the psychometric properties of The Health of the Nation Outcome Scale (HoNOS) using the Classical Test Theory and the Rating Scale Model, a Rasch-type model used for polytomous items. The HoNOS is one of the most widely used scales to assess outcomes routinely in mental health services. The original version for adults has been translated into Spanish (Uriarte et al., 1999) but no empirical studies have been carried out on the psychometric properties of this version. Participants were 402 users of four outpatient mental health services and the psychiatric hospital in Uruguay. The response category system, the fit of people and items to the Rasch model, reliability, discriminant validity and sensitivity to change were analyzed. The results showed that the original HoNOS five-category system did not function correctly according to the Linacre (2002) recommendations. A solution was sought by adding adjacent categories, reducing the initial categories to four that showed better performance. An acceptable fit of the instrument to the model requirements was observed. The scale showed adequate validity to discriminate patients with different levels of severity and sensitivity to change. It is concluded that the HoNOS meets some desirable characteristics as a measure for evaluating the outcomes of mental health services. The original HoNOS presents some metric problems that can be improved by reducing the response categories to four.