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.
Keywords: Rasch analysis; condition-specific quality of life; health-related quality of life; outcome instrument; traumatic brain injury.
© The Author(s) 2015.