Table 2.

TBI exposure ascertainment

Life-course TBI exposure
Index injury (ie, exposed vs unexposed within the ADVANCE Study; defined as requiring medical evacuation for trauma, vs non-trauma exposed control)			Additional exposures
Battlefield trauma exposed		Unexposed
TBI±extracranial injuries	Extracranial injuries alone	No ‘index’ injury	Previous or subsequent TBIs (N) Repeated head impacts (type, duration)

Characterisation of life-course exposure to TBI. The participant may, for the purposes of the ADVANCE cohort study, be defined as ‘exposed’ (ie, having a major combat traumatic injury requiring medical evacuation) or ‘unexposed’ (left column). This is referred to as the ‘index’ injury. This may or may not include TBI. Separate from this, we will ascertain other injuries (‘additional exposures', right column) with TBI.

ADVANCE, ArmeD SerVices TrAuma and RehabilitatioN OutComE; TBI, traumatic brain injury.