title: Relationship Between Physician and Hospital Procedure Volume and Mortality After Carotid Artery Stenting Among Medicare Beneficiaries.
abstract: BACKGROUND
  Clinical trials demonstrated the efficacy of carotid artery stenting (CAS) relative to carotid endarterectomy when performed by physicians with demonstrated proficiency. It is unclear how CAS performance may be influenced by the diversity in CAS and non-CAS provider volumes in routine clinical practice.
  
  
  RESULTS
  We linked Medicare claims to the Centers for Medicare and Medicaid Services' CAS Database (2005-2009). We assessed the association between 30-day mortality and past-year physician (0, 1-4, 5-9, 10-19, ≥20) and hospital (<10, 10-19, 20-39, ≥40) CAS volumes and past-year hospital coronary and peripheral stenting volumes (<200, 200-399, 400-849, ≥850) among beneficiaries at least 66 years of age. Unadjusted 30-day mortality risk was 1.8% (95% confidence interval [CI], 1.6-2.0) for 19 724 patients undergoing CAS by 2045 physicians in 729 hospitals. Median past-year CAS volume was 9 (interquartile range, 4-19) for physicians and 23 (interquartile range, 12-41) for hospitals. Compared to physicians performing ≥20 CAS in the past year, lower CAS volumes were associated with higher adjusted risks of 30-day morality (P value for trend < 0.05): 1.4 (95% CI, 0.9-2.3) for 0 past-year CAS, 1.3 (95% CI, 0.9-1.8) for 1 to 4, 1.1 (95% CI, 0.8-1.6) for 5 to 9, and 0.9 (95% CI, 0.7-1.4) for 10 to 19. An inverse relationship between 30-day mortality and past-year CAS hospital volume as well as past-year hospital non-CAS volume, past-year hospital non-CAS volume, and 30-day mortality was also noted.
  
  
  CONCLUSIONS
  Among Medicare patients, an inverse relationship exists between physician and hospital CAS volumes and hospital non-CAS stenting volume and 30-day mortality, even after adjusting for all pertinent patient- and hospital-level factors.
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Jessica J
authors.initials: JJ
authors.lastname: Jalbert
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Marie D
authors.initials: MD
authors.lastname: Gerhard-Herman
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Louis L
authors.initials: LL
authors.lastname: Nguyen
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Michael R
authors.initials: MR
authors.lastname: Jaff
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Hiraku
authors.initials: H
authors.lastname: Kumamaru
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Williams
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Chih-Ying
authors.initials: CY
authors.lastname: Chen
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: John D
authors.initials: JD
authors.lastname: Seeger
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Rothman
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Peter
authors.initials: P
authors.lastname: Schneider
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Brott
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Tsai
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Herbert D
authors.initials: HD
authors.lastname: Aronow
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.).
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Johnston
authors.affiliation: From the Division of Pharmacoepidemiology and Pharmacoeconomics (J.J.J., H.K., L.A.W., C.-Y.C., J.L., J.D.S., A.T.R., S.S.), Division of Cardiovascular Medicine (M.D.G.-H.), and Division of Vascular and Endovascular Surgery (L.L.N.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Division of Consulting and Analytics, LASER Analytica, New York, NY (J.J.J.); Division of Cardiovascular Medicine, Massachusetts General Hospital, Boston (M.R.J.); Division of Vascular and Endovascular Surgery, Kaiser Permanente Medical Centre, Honolulu, HI (P.S.); Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.); Division of Cardiology, Denver VA Medical Center, University of Colorado (T.T.T.); Division of Cardiovascular Medicine, St Joseph Mercy Hospital, Ann Arbor, MI (H.D.A.); Global Health Outcomes, Lilly Research Laboratories, Eli Lilly and Company Indianapolis, IN (J.A.J.); and Department of Medicine, Duke Clinical Research Institute, Durham, NC (S.S.). soko@post.harvard.edu.
authors.forename: Soko
authors.initials: S
authors.lastname: Setoguchi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019917:Blood Vessel Prosthesis Implantation / Q000401:mortality; D002339:Carotid Arteries / Q000601:surgery*; D016893:Carotid Stenosis / Q000453:epidemiology* / Q000401:mortality / Q000601:surgery; D002986:Clinical Trials as Topic; D015331:Cohort Studies; D016894:Endarterectomy, Carotid; D005260:Female; D061847:Hospitals, High-Volume / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D006278:Medicare; D018579:Patient Selection; D010820:Physicians / Q000706:statistics & numerical data*; D011364:Professional Practice; D015607:Stents / Q000706:statistics & numerical data; D016019:Survival Analysis; D014481:United States
keywords: Medicare; carotid endarterectomy; carotid stenting; mortality; provider performance