Predictors and indicators of disability and quality of life 4 years after a severe traumatic brain injury. A Structural Equation Modelling analysis from the PariS-TBI study

ObjectiveTo assess the predictors and indicators of disability and quality of life four years after a severe traumatic brain injury (TBI), using a Structural Equation Modelling (SEM). SEM is a multivariate approach permitting to take into account the complex inter-relationships between individual predictors, in order to disentangle factors which have a direct or indirect relationship with the dependant variable.MethodsThe Paris-TBI study is a longitudinal inception cohort study of 504 patients with severe TBI in the Parisian area [1]. Among 245 survivors, 147 patients were assessed four years post-injury. Two outcome measures were analysed separately using SEM: the Glasgow Outcome Scale-extended (GOS-E) [2], which is a global measure of disability after TBI, and the QOLIBRI, a disease-specific measure of quality of life after TBI [3]. Four groups of variable were entered in the model: demographics; injury severity; psychological and cognitive impairments; somatic impairments.ResultsThe GOS-E was directly significantly related to all four groups of variables (age, gender, severity of injury, psycho-cognitive and somatic impairments). Education duration had an indirect effect, mediated by psycho-cognitive impairments. In contrast, the QOLIBRI was only directly predicted by psycho-cognitive impairments. Age and somatic impairments had an indirect influence on the QOLIBRI, via psycho-cognitive impairments.Discussion/ConclusionDisability and quality of life were directly influenced by different factors. While disability appeared to result from an interaction of a wide range of factors, including demographics, injury severity, psycho-cognitive and somatic deficiencies, quality of life was solely directly related to psycho-cognitive factors. Other factors, such as age and somatic impairments only had an indirect effect