Content » Vol 51, Issue 8

Original report

Rasch analysis of the UK Functional Assessment Measure in a sample of patients with traumatic brain injury from the UK national clinical database

Lynne Turner-Stokes, Oleg N. Medvedev, Richard J. Siegert
Departmant of Palliative Care, Policy and Rehabilitation, King's College London, London, UK. E-mail:
DOI: 10.2340/16501977-2580


Objective: To determine whether the UK Functional Assessment Measure (UK FIM+FAM) fits the Rasch model in patients with complex disability following traumatic brain injury.
Design: Psychometric evaluation including preliminary exploratory and confirmatory factor analyses followed by Rasch analysis.
Participants: A multicentre UK national cohort of 1,956 patients admitted for specialist rehabilitation following traumatic brain injury.
Results: The suitability of the Partial Credit Model was confirmed by the likelihood-ratio test (χ2 (df86) =7,325. 0, p < 0. 001). Exploratory and confirmatory factor analyses supported 3 factors (Motor, Communication, Psychosocial). Rasch analysis of the full scale incorporating the 3 factors as super-items resulted in an acceptable overall model fit (χ2 (df24)=36. 72, p = 0. 05) and strict uni-dimensionality when tested on a sub-sample of n = 320. These results were replicated in a full sample (n = 1,956) showing uni-dimensionality and good reliability with Person Separation Index = 0. 81, but item trait interaction was significant due to the large sample size. No significant differential item functioning was observed for any personal factors. Neither uniform re-scoring of items nor exclusion of participants with extreme scores improved the model fit.
Conclusion: The UK FIM+FAM scale satisfies the Rasch model reasonably in traumatic brain injury. A conversion table was produced, but its usefulness in clinical practice requires further exploration and clinical translation.

Lay Abstract

The UK Functional Assessment Measure (UK FIM+FAM) is a scale used to evaluate the outcome of rehabilitation after acquired brain injury as part of the UK Rehabilitation Outcomes Collaborative (UKROC). The FIM+FAM is administered by clinicians and measures how well -people are recovering their independence. It has 30 separate questions concerning a person’s physical (e.g. eating, toileting, bathing) and cognitive (e.g. expression, memory, safety awareness) independence. Data from 1,956 UK patients who had survived a traumatic brain injury were analysed. The main purpose of this study was to establish that the FIM+FAM meets some of the stringent technical standards for clinical and scientific measurement. A statistical method known as Rasch analysis was used to demonstrate that the FIM+FAM produces accurate and reliable scores. The results showed that the FIM+FAM is a practical and useful scale for measuring change in people in rehabilitation after a traumatic brain injury.

Supplementary content


Do you want to comment on this paper? The comments will show up here and if appropriate the comments will also separately be forwarded to the authors. You need to login/create an account to comment on articles. Click here to login/create an account.