Objective: To compile a minimum data set for the follow-up of traumatic brain injury patients from discharge from hospital to one year post injury to assess functioning and participation in the physical, cognitive and psychosocial domains, and in quality of life.

Design: Repeated questionnaire interviews by two observers to establish interobserver reliability of the measurement instruments at discharge and at one year post injury, as well as their sensitivity to change over time in traumatic brain injury patients.

Setting: Department of neurosurgery of an academic hospital, department of a rehabilitation centre, and at the patients' homes in the Netherlands.

Subjects: The study at discharge included 25 patients aged 18-50 years with a moderate to severe traumatic brain injury (Glasgow Coma Scale score 3-14), whereas the one year post injury study included 14 patients aged 19-51 years.

Main (outcome) measures: Physical domain: Barthel Index (BI), Functional Independence Measurement (FIM), Glasgow Outcome Scale (GOS), GOS Extended (GOSE). Cognitive domain: Disability Rating Scale (DRS), Functional Assessment Measurement (FAM), Levels of Cognitive Functioning Scale (LCFS), Neurobehavioural Rating Scale (NRS). Psychosocial domain: Community Integration Questionnaire (CIQ), Employability Rating Scale (ERS), Frenchay Activity Index (FAI), Multi Health Locus of Control (MHLC), Rehabilitation Activities Profile (RAP), Social Support List (SSL), Supervision Rating Scale (SRS), Wimbledon Self Reporting Rating Scale (WSRS). Quality of life: Coop/Wonca Charts (Coop), Rand SF-36 (Rand-36), Sickness Impact Profile-68 (SIP-68).

Results: At both discharge and at one year post injury, in the physical domainthe FIM showed excellent squared weighted kappa (SWK ranging from 0.75 to 0.80), and intraclass correlation coefficient (ICC ranging from 0.75 to 0.92), and a relatively small standard error of measurement (SEM 3.22) and smallest detectable difference (SDD 8.92). In the cognitive domain the FAM and the NRS showed excellent SWK, and ICC, and a relatively small SEM and SDD. In the psychosocial domainthe FAI showed excellent SWK (0.89), and ICC (0.87), and a relatively small SEM (2.64) and SDD (7.31). For quality of life, at both discharge and at one year post injury the SIP-68 and the Coop showed excellent SWK (0.87), and ICC (0.89), and a relatively small SEM (3.79) and SDD (10.51). At both time points SWK and ICC ranged from 0.80 to 0.89, SEM ranged from 1.47 to 1.98, and the SDD was 4.07.

Conclusions: An example of a reliable minimum data set that is also able to detect changes over time is: the FIM, the FAM and the Coop for the early stages in recovery, extended with the NRS, the FAI, and the SIP-68 later in recovery, thereby covering all relevant domains after traumatic brain injury.