One hundred and thirty-seven studies with 142 cohorts were included in the review (13,698 participants and 46,314 patient-years of follow-up). None of the studies were in the form of a randomised controlled trial (RCT). All were observational in design.
Case fatality was 1.1 (95% CI 0.87 to 1.3) per 100 person-years after microsurgery, 0.50 (95% CI 0.43 to 0.58) after stereotactic radiosurgery and 0.96 (95% CI 0.67 to 1.4) after embolisation. Internal haemorrhage rates were 0.18 (95% CI 0.10 to 0.30) per 100 person-years after microsurgery, 1.7 (95% CI 1.5 to 1.8) after stereotactic radiosurgery and 1.7 (95% CI 1.3 to 2.3) after embolisation.
Complications that led to permanent neurological deficits or death occurred in a median of 7.4% (range 0% to 40%) after microsurgery, 5.1% (range 0% to 21%) after stereotactic radiosurgery and 6.6% (range 0% to 28%) after embolisation.
Obliteration was achieved in 96% (range 0% to 100%) of patients after microsurgery, 38% (range 0% to 75%) after stereotactic radiosurgery and 13% (range 0% to 94% after embolisation.
Further results of determinants of these outcomes and sensitivity analyses are detailed in the report.