This is a five year multi-site, cross sectional, observational study designed to examine chronic pain and pain treatment after moderate to severe TBI.

The aims of this study are to: 1) Determine chronic pain classification (musculoskeletal, headache, central/neuropathic), prevalence, location, duration, and associations with demographic, injury severity, current level of functioning and comorbidities in participants followed in ten Centers participating in the National Institute on Disability, Independent Living and Rehabilitation Research and the Department of Veterans Affairs TBIMS Databases; 2) Identify extreme groups based on responses to pain (interference and perception of improvement with treatment), or chronic pain extreme phenotypes, in order to define the key differences between those who have a good outcome and those who do not, across factors related to injury, pain severity/location, demographics, and treatment history; and 3) Identify treatment practices by clinicians who treat comorbid TBI and chronic pain to determine gaps in availability/accessibility of guideline level treatment, highlighting underserved populations where applicable.

Results from this study will provide a more detailed picture of the problem of chronic pain after TBI by examining the types of pain that occur after TBI, which may be multiple types of pain for a subset of individuals, as well as the frequency of comorbid conditions. Identifying extreme phenotypes, such as demographic, individual, and treatment factors associated with those who have chronic pain but have minimal interference compared to those who are significantly impacted by pain, will allow us to identify treatment targets (behavioral, cognitive, biological, and molecular) to advance a personalized medicine approach to treatment unlike any approach in TBI and chronic pain to date. Outcomes from this study will include educational materials on chronic pain and pain treatment to benefit patients, family members, clinicians, and policymakers. Data from this study will have a direct impact on clinical practice, informing future work, and promoting understanding of constituent factors in extreme phenotypes.

Inclusion Criteria:

• Participants must be enrolled in the TBI Model Systems National Database (TBNIMS NDB) at one of the collaborating sites and thus will meet the TBIMS NDB criteria which are: (1) medical documentation of TBI caused by external mechanical force with either loss of consciousness exceeding 30 minutes, post-traumatic amnesia lasting more than 24 hours, Glasgow Coma Scale score in ER of less than 13, or trauma related intracranial abnormality or neuroimaging abnormalities; (2) admitted to the TBI inpatient rehab program at study sites; and (3) minimum age of 16 [18 for VA site]

Exclusion Criteria:

• Participants unable to participate in the surveys themselves will not be included (i.e. no proxy surveys).

All participants have sustained a moderate to severe TBI and are now being followed at the collaborating centers as part of the TBIMS NDB which is a study collecting observational data after TBI.