The Australian Traumatic Brain Injury Initiative: systematic review and consensus process to determine the predictive value of pre-existing health conditions for people with moderate-severe traumatic brain injury.

The first aim of the Australian Traumatic Brain Injury Initiative (AUS-TBI) encompasses development of a set of measures that comprehensively predict outcomes for people with moderate-severe TBI across Australia. This process engaged diverse stakeholders and information sources across six areas: social, health, and clinical factors, biological markers, treatments, and longer-term outcomes. Here, we report the systematic review of pre-existing health conditions as predictors of outcome for people with moderate-severe TBI. Standardised searches were implemented across databases until 31 March 2022. English-language reports of studies evaluating association between pre-existing health conditions and clinical outcome in at least ten patients with moderate-severe TBI were included. A pre-defined algorithm was used to assign a judgement of predictive value to each observed association. The list of identified pre-existing health conditions was then discussed with key stakeholders during a consensus meeting to determine the feasibility of incorporating them into standard care. The searches retrieved 22,217 records, of which 47 papers were included. The process led to identification of 88 unique health predictors (homologised to 21 predictor categories) of 55 outcomes (homologised to 19 outcome categories). Only pre-existing health conditions with high and moderate predictive values were discussed during the consensus meeting. Following the consensus meeting, five out of 11 were included (migraine, mental health conditions, ≥ four pre-existing health conditions, osteoporosis and BMI) as common data elements in the AUS-TBI data dictionary. Upon further discussion, three additional pre-existing health conditions were included. These are pre-existing heart disease, frailty score and previous incidence of TBI.