Table 1.
Risk of bias of studies assessing CBF using ASL in mTBI (AAN rating criteria)
| Class I Requirements1 | ||||||
|---|---|---|---|---|---|---|
| Prospective cohort | Relevant confounds equivalent/controlled for | Clear inclusion/exclusion criteria | ≥80% complete data | Downgrades | Risk of bias | |
| Maximum class if criterion not met: | II | III | IV | III | III | |
| Barlow, 2017 | N | Y | N5 | N7 | - | IV |
| Brooks, 2019 | N | Y | Y | Y | - | II |
| Churchill, 2017a | N | Y | Y | Y | - | II |
| Churchill, 2017b | N | Y | Y | Y | - | II |
| Churchill, 2019a | N | Y | Y | Y | - | II |
| Churchill, 2019b | N | Y | Y | Y | - | II |
| Coverdale, 2020 | N | Y | Y | Y | - | II |
| Doshi, 2018 | N | Y | Y | N8 | - | III |
| Ge, 2009 | N | Y | N5 | Y | IV | |
| Hamer, 2019 | N | Y (female group); N (male group)2 |
N | Y | IV | |
| Lin, 2016 | N | Y | Y | Y | - | II |
| Liu, 2016 | N | Y | Y | Y | - | II |
| Meier, 2018 | N | Y | N6 | N (Time 3) | - | IV |
| Militana, 2016 | N | Y | N6 | Y | - | IV |
| Moller, 2017 | N | Y | Y | Y | narrow patient spectrum10 | III |
| Mutch, 2016 | N | N3 | N6 | Y | narrow patient spectrum | IV |
| Mutch, 2018 | N | N3 | Y | N9 | historical controls | III |
| Peng, 2016 | N | Y | N5 | Retention NR | - | IV |
| Sours, 2015 | N | Y (primary group comparison); N (secondary analysis)4 |
N5 | Excluded cases NR | - | IV |
| Stephens, 2018 | N | Y | Y | Y | narrow patient spectrum | III |
| Wang, 2015 | N | Y | N5 | Y | narrow patient spectrum | IV |
| Wang, 2016 | Y | Y | Y | Y | - | I |
| Wang, 2019 | Y | Y | Y | Excluded cases NR | - | I |
Note. Studies are listed by the first author last name and publication year. Because of ambiguity around when patients met the outcome (cerebral blood flow changes), studies were conservatively only considered prospective if they enrolled subjects pre-injury. AAN = American Academic of Neurology; NR = not reported
Requirements met by all studies (objective outcome, clearly defined primary outcomes) are not listed
Analyses did not control for age despite significant age difference between male cases and controls
Age/gender matching not reported in the paper but was verified as not significantly different between groups based on the data presented
Second analysis of mTBI subgroups did not control for age despite significant age difference between groups
Definitions of concussion/mTBI that did not clearly require both trauma and either AMS or concussion symptoms were considered insufficient
Physician diagnoses made without clearly indicating a specific definition of mTBI/concussion were considered insufficient
79% of symptomatic mTBI group could complete the MRI
2/7 patients excluded for motion artifact
21% of controls excluded for motion artifact
Narrow patient spectrum declared for any sample recruited entirely from a concussion/mTBI clinic