Modelling 5-year functional outcome in a major traumatic injury survivor cohort

Abstract

Aim. To estimate associations between possible predictors of functional disability outcome at 5 years in a working adult population cohort of survivors of major traumatic injury and to develop a prognostic model of outcome.

Design. Population based retrospective cohort study.

Population. Persons who had experienced major traumatic injury (Injury Seventy Score >15) in the area of the former Yorkshire Regional Health Authority during the period 30 September 1988 to 1 October 1989 and who survived for 5 years (average 5.3 years).

Methods. The same interviewer saw each survivor at their home and used the OPCS Adult Disability Schedule to ascertain levels of functional disability. Disability scores for each survivor were then combined in accordance with the OPCS guidance to calculate a level of disability between 0 (no disability) to 10 (maximum disability). The OPCS level was then dichotomised with a cut-point at 4/5. Possible predictor and confounding variables from pre-injury, injury and post-injury periods were modelled in a logistic regression to identify those that predicted outcome level. Two reduced models were developed to allow early prognosis of late outcome.

Results. The full model correctly classified 91% of observed outcomes. Inpatient length of stay OR 1.031 (95% CI 1.014,1.048) per day predicted poorer 5-year outcome; Glasgow Coma Score OR 0.790(0.629,0.992) per 1 point increase; stay in Intensive Care Unit OR 0.931 (0.877,0.987) per day; attainment of degree-level education OR 0.014 (0.000,0.707); single civil status OR 0.110 (0.013,0.908); being taken initially to a hospital with a neurosurgical facility OR 0.064(0.010,0.420); being in paid work during the 2 weeks before index injury OR 0.093(0.009,0.969) predicted better 5-year disability outcome. Two reduced models were constructed that included a simple set of variables, one of these models excluded any rehabilitation variables but still correctly classified 85% of the observed outcomes.

Conclusion. As well as level of traumatic brain injury (TBI) and total inpatient stay, Pre-injury educational attainment and employment, civil status, immediate care in a hospital with a neurosurgical facility and stay in an Intensive Care Unit determined 5-year outcome. It is possible to efficiently predict outcome at an early stage. Previous work on predictors of disablement have suffered from large selection and attrition biases.

Keywords:

• Five year outcome
• disability
• traumatic brain injury
• major traumatic injury