title: New York State: Comparison of Treatment Outcomes for Unruptured Cerebral Aneurysms Using an Instrumental Variable Analysis.
abstract: BACKGROUND
  There is wide regional variation in the predominant treatment for unruptured cerebral aneurysms. We investigated the association of elective surgical clipping and endovascular coiling with mortality, readmission rate, length of stay, and discharge to rehabilitation.
  
  
  RESULTS
  We performed a cohort study involving patients with unruptured cerebral aneurysms, who underwent surgical clipping or endovascular coiling from 2009 to 2013 and were registered in the Statewide Planning and Research Cooperative System database. An instrumental variable analysis was used to investigate the association of treatment technique with outcomes. Of the 4643 patients undergoing treatment, 3190 (68.7%) underwent coiling, and 1453 (31.3%) underwent clipping. Using an instrumental variable analysis, we did not identify a difference in inpatient mortality (marginal effect, 0.13; 95% CI, -0.30, 0.57), or the rate of 30-day readmission (marginal effect, -1.84; 95% CI -4.06, -0.37) between the 2 treatment techniques for patients with unruptured cerebral aneurysms. Clipping was associated with a higher rate of discharge to rehabilitation (marginal effect, 2.31; 95% CI 0.21, 4.41), and longer length of stay (β, 2.01; 95% CI 0.85, 3.04). In sensitivity analysis, mixed-effect regression, and propensity score, adjusted regression models demonstrated identical results.
  
  
  CONCLUSIONS
  Using a comprehensive all-payer cohort of patients in New York State with unruptured cerebral aneurysms, we did not identify an association of treatment method with mortality or 30-day readmission. Clipping was associated with a higher rate of discharge to rehabilitation and longer length of stay.
authors.affiliation: Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH (K.B., R.J.S.).
authors.forename: Kimon
authors.initials: K
authors.lastname: Bekelis
authors.affiliation: Department of Neurosurgery, Louisiana State University Health Sciences Center, Shreveport, LA (S.M.).
authors.forename: Symeon
authors.initials: S
authors.lastname: Missios
authors.affiliation: Geisel School of Medicine at Dartmouth, Hanover, NH (S.C.).
authors.forename: Shannon
authors.initials: S
authors.lastname: Coy
authors.affiliation: Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH (K.B., R.J.S.).
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Singer
authors.affiliation: Department of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH (T.A.M.K.) Department of Community and Family Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH (T.A.M.K.) The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, NH (T.A.M.K.).
authors.forename: Todd A
authors.initials: TA
authors.lastname: MacKenzie
mesh_terms: D000328:Adult; D000368:Aged; D057225:Data Mining; D016208:Databases, Factual; D057510:Endovascular Procedures / Q000009:adverse effects / Q000295:instrumentation / Q000401:mortality; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D007902:Length of Stay; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009518:New York / Q000453:epidemiology; D016017:Odds Ratio; D010351:Patient Discharge; D010359:Patient Readmission; D057216:Propensity Score; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000009:adverse effects / Q000401:mortality
keywords: clipping; coiling; instrumental variable; statewide planning and research cooperative system; unruptured cerebral aneurysm