A Rasch Analysis of the QOLIBRI Six-Item Overall Scale

Abstract

Objective: The Quality Of Life after BRain Injury (QOLIBRI) consortium has developed a short six-item scale (QOLIBRI-OS) to screen health-related quality of life after traumatic brain injury. The goal of the current study is to examine further psychometric qualities of the Quality Of Life after BRain Injury-Overall Scale (QOLIBRI-OS) at the item level using Rasch analysis with particular emphasis on the operating characteristics of the items. Method: A total of 921 participants with traumatic brain injury were recruited. The analysis sample was restricted to 795 participants with Glasgow Coma Score and Glasgow Outcome Score–Extended available in order to ensure a well-characterized sample. Results: Overall fit statistics indicate sufficient reliability of the QOLIBRI-OS. The assumption of unidimensionality could be confirmed with reservation. The range of item locations is small, whereas item thresholds cover a wide range of the latent trait. The majority of parameter estimations for all class intervals of the respective test are in accordance with the model assumptions. Conclusion: The results show that, despite marginal misfits to the model, the six items representing the QOLIBRI-OS could establish a Rasch scale.