Between-center and between-country differences in outcome after aneurysmal subarachnoid hemorrhage in the Subarachnoid Hemorrhage International Trialists (SAHIT) repository

Restricted access


Differences in clinical outcomes between centers and countries may reflect variation in patient characteristics, diagnostic and therapeutic policies, or quality of care. The purpose of this study was to investigate the presence and magnitude of between-center and between-country differences in outcome after aneurysmal subarachnoid hemorrhage (aSAH).


The authors analyzed data from 5972 aSAH patients enrolled in randomized clinical trials of 3 different treatments from the Subarachnoid Hemorrhage International Trialists (SAHIT) repository, including data from 179 centers and 20 countries. They used random effects logistic regression adjusted for patient characteristics and timing of aneurysm treatment to estimate between-center and between-country differences in unfavorable outcome, defined as a Glasgow Outcome Scale score of 1–3 (severe disability, vegetative state, or death) or modified Rankin Scale score of 4–6 (moderately severe disability, severe disability, or death) at 3 months. Between-center and between-country differences were quantified with the median odds ratio (MOR), which can be interpreted as the ratio of odds of unfavorable outcome between a typical high-risk and a typical low-risk center or country.


The proportion of patients with unfavorable outcome was 27% (n = 1599). The authors found substantial between-center differences (MOR 1.26, 95% CI 1.16–1.52), which could not be explained by patient characteristics and timing of aneurysm treatment (adjusted MOR 1.21, 95% CI 1.11–1.44). They observed no between-country differences (adjusted MOR 1.13, 95% CI 1.00–1.40).


Clinical outcomes after aSAH differ between centers. These differences could not be explained by patient characteristics or timing of aneurysm treatment. Further research is needed to confirm the presence of differences in outcome after aSAH between hospitals in more recent data and to investigate potential causes.

ABBREVIATIONS aSAH = aneurysmal subarachnoid hemorrhage; CI = confidence interval; GOS = Glasgow Outcome Scale; IHAST = Intraoperative Hypothermia for Aneurysm Surgery Trial; IQR = interquartile range; MASH = Magnesium Sulfate in Aneurysmal Subarachnoid Hemorrhage; MOR = median odds ratio; mRS = modified Rankin Scale; RCT = randomized clinical trial; SAHIT = Subarachnoid Hemorrhage International Trialists; TBI = traumatic brain injury; WFNS = World Federation of Neurosurgical Societies.

Downloadable materials

  • Supplemental Content (PDF 692 KB)

Article Information

Correspondence Simone Dijkland: Erasmus MC–University Medical Center, Rotterdam, The Netherlands.

INCLUDE WHEN CITING Published online August 23, 2019; DOI: 10.3171/2019.5.JNS19483.

Disclosures R.L.M. reports grants from the Brain Aneurysm Foundation, the Heart and Stroke Foundation of Canada, and Genome Canada outside the present workhaving a patent on a drug delivery system for treatment of cerebral vasospasm issued; and having been Chief Scientific Officer and an employee of Edge Therapeutics, Inc. J.I.S. reports grants from PCORI and support from BARD and Neurocritical Care Society outside the present work. S.A.M. reports personal fees from Idorsia Pharmaceuticals and Edge Therapeutics outside the present work. M.D.C. reports grants from Cancer Care Ontario, Canadian Institute for Military and Veteran Health Research, Mitacs Canada, Physicians’ Services Inc. Foundation, and Academic Health Science Center Alternative Funding Plan outside the present work. G.S. is Associate Editor of the Emerging Therapies Section of Stroke.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Observed number of patients per center (left) in each of 179 centers, with numbers varying from 1 to 846 (median 20, IQR 11–37) and per country (right) in each of 20 countries, with numbers varying from 9 to 1765 (median 109, IQR 31–334).

  • View in gallery

    Differences between centers (left) and countries (right) in unfavorable outcome, adjusted for age, history of hypertension, WFNS grade, Fisher grade, aneurysm location, aneurysm size, and time from aSAH to aneurysm treatment in a random effects model. The circles indicate the random effects for the individual centers (betas), and the size of the circle refers to the number of patients in each center. The lines reflect the 95% CIs.




All Time Past Year Past 30 Days
Abstract Views 294 294 218
Full Text Views 100 100 82
PDF Downloads 58 58 49
EPUB Downloads 0 0 0


Google Scholar