Table 2 Assessment of Study Applicability based on Agency for Healthcare Research and Quality Methods

Level III

Sample is representative of the entire traumatic brain injury (TBI) population or the results are applicable to the entire TBI population

Level II

Sample is representative of a relevant subgroup of the target TBI population (i.e., patients <1 year post-injury, patients <65 years of age, etc.)

Level I

Sample is only representative of a narrow subgroup of the target TBI population and not well generalizable to other subgroups