title: Risk of stroke after chiropractic spinal manipulation in medicare B beneficiaries aged 66 to 99 years with neck pain.
abstract: OBJECTIVE
  The purpose of this study was to quantify risk of stroke after chiropractic spinal manipulation, as compared to evaluation by a primary care physician, for Medicare beneficiaries aged 66 to 99 years with neck pain.
  
  
  METHODS
  This is a retrospective cohort analysis of a 100% sample of annualized Medicare claims data on 1 157 475 beneficiaries aged 66 to 99 years with an office visit to either a chiropractor or primary care physician for neck pain. We compared hazard of vertebrobasilar stroke and any stroke at 7 and 30 days after office visit using a Cox proportional hazards model. We used direct adjusted survival curves to estimate cumulative probability of stroke up to 30 days for the 2 cohorts.
  
  
  RESULTS
  The proportion of subjects with stroke of any type in the chiropractic cohort was 1.2 per 1000 at 7 days and 5.1 per 1000 at 30 days. In the primary care cohort, the proportion of subjects with stroke of any type was 1.4 per 1000 at 7 days and 2.8 per 1000 at 30 days. In the chiropractic cohort, the adjusted risk of stroke was significantly lower at 7 days as compared to the primary care cohort (hazard ratio, 0.39; 95% confidence interval, 0.33-0.45), but at 30 days, a slight elevation in risk was observed for the chiropractic cohort (hazard ratio, 1.10; 95% confidence interval, 1.01-1.19).
  
  
  CONCLUSIONS
  Among Medicare B beneficiaries aged 66 to 99 years with neck pain, incidence of vertebrobasilar stroke was extremely low. Small differences in risk between patients who saw a chiropractor and those who saw a primary care physician are probably not clinically significant.
authors.affiliation: Instructor, The Dartmouth Institute for Health Policy & Clinical Practice, Dartmouth College, Grantham, NH. Electronic address: james.m.whedon@hitchcock.org.
authors.forename: James M
authors.initials: JM
authors.lastname: Whedon
authors.affiliation: Research Associate, The Dartmouth Institute for Health Policy & Clinical Practice, Dartmouth College, Grantham, NH.
authors.forename: Yunjie
authors.initials: Y
authors.lastname: Song
authors.affiliation: Associate Professor, The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth College, Grantham, NH.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Mackenzie
authors.affiliation: President Emeritus, Southern California University of Health Sciences, Whittier, CA.
authors.forename: Reed B
authors.initials: RB
authors.lastname: Phillips
authors.affiliation: Associate Professor of Neurology, Geisel School of Medicine, Dartmouth College, Grantham, NH.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Lukovits
authors.affiliation: Associate Professor, The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth College, Grantham, NH.
authors.forename: Jon D
authors.initials: JD
authors.lastname: Lurie
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D026882:Manipulation, Chiropractic / Q000009:adverse effects* / Q000379:methods; D020393:Manipulation, Spinal / Q000009:adverse effects* / Q000379:methods; D006278:Medicare / Q000191:economics / Q000706:statistics & numerical data; D019547:Neck Pain / Q000175:diagnosis / Q000534:rehabilitation*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D020521:Stroke / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors; D014481:United States
keywords: Chiropractic; Medicare; Neck Pain; Spinal Manipulation, Adverse Effects; Stroke; Vertebral Artery Dissection