Table 1.

Modified Newcastle-Ottawa Scale

(adapted from [15])

Domain	Outcome assessed
Selection	Representativeness of the exposed cohort (one point) Were BSG patients representative of the BSG patient that is typical in neurooncology practice?	Ascertainment of exposure (one point) Did the study specify where the information confirming diagnosis was taken from?
Comparability	Study controls for any additional factor (one point)
Outcome	Was follow-up long enough for outcomes to occur (one point) Did follow up occur for at least 1 year?	Adequacy of follow up of cohorts (one point) Did the study account for all participants when assessing outcome of interest?