title: Statins and subarachnoid hemorrhage in Medicare patients with unruptured cerebral aneurysms.
abstract: BACKGROUND
  Statins have been shown to decrease aneurysm progression and rupture in two experimental settings: animals with cerebral aneurysm and humans with abdominal aortic aneurysms.
  
  
  OBJECTIVE
  To investigate statin use and outcomes in humans with unruptured cerebral aneurysms through Medicare administrative data.
  
  
  METHODS
  We used a 40% random sample Medicare denominator file and corresponding inpatient, outpatient (2003-2011), and prescription (2006-2011) claims to conduct a retrospective cohort study of patients diagnosed with unruptured cerebral aneurysms, between 2003 and 2011. We used propensity score-adjusted models to investigate the association between statin use and risk of subarachnoid hemorrhage. Secondary analyses repeated the main models stratified on tobacco use status and separately assessed other composite outcomes.
  
  
  RESULTS
  We identified 28 931 patients with unruptured cerebral aneurysms (average age 72·0 years, 72·6% female); mean follow-up was 30·0 months; 41·3% used statins. Overall, 593 patients developed subarachnoid hemorrhage, and 703 underwent treatment before subarachnoid hemorrhage. Current or recent statin use was not associated with a difference in subarachnoid hemorrhage risk (odds ratio, 1·03; 95% conflict of interest 0·86-1·23); models stratified on tobacco use status were nearly identical. No association was observed between statin use and the composite outcome of subarachnoid hemorrhage or aneurysm treatment (odds ratio, 0·94; 95% conflict of interest, 0·84-1·06). The risk of subarachnoid hemorrhage or out-of-hospital death was lower among statin users (odds ratio, 0·69; 95% conflict of interest, 0·64-0·74).
  
  
  CONCLUSIONS
  Statin use by patients with unruptured cerebral aneurysms was not associated with subarachnoid hemorrhage risk. Given the prior animal experimental studies demonstrating a protective effect, further prospective studies are needed to investigate the potential relationship.
authors.affiliation: Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.
authors.forename: Kimon
authors.initials: K
authors.lastname: Bekelis
authors.affiliation: The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, NH, USA.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Smith
authors.affiliation: The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, NH, USA.
authors.forename: Weiping
authors.initials: W
authors.lastname: Zhou
authors.affiliation: The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, NH, USA.|Department of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.|Department of Community and Family Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.
authors.forename: Todd A
authors.initials: TA
authors.lastname: MacKenzie
authors.affiliation: Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.|Department of Neurology, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.|Geisel School of Medicine at Dartmouth, Hanover, NH, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Roberts
authors.affiliation: The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, NH, USA.|Department of Economics, Dartmouth College, Hanover, NH, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Skinner
authors.affiliation: The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, NH, USA.|Department of Community and Family Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.|Geisel School of Medicine at Dartmouth, Hanover, NH, USA.
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Morden
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000188:drug therapy* / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D002532:Intracranial Aneurysm / Q000188:drug therapy* / Q000453:epidemiology; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data*; D016017:Odds Ratio; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000517:prevention & control*; D014481:United States
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors
keywords: Medicare; cerebral aneurysms; statins; subarachnoid hemorrhage