• Choi S
• Boyle E
• Côté P
• Cassidy JD

• Iatrogenic Disease
• Stroke / etiology
• Stroke / Ontario
• Vertebrobasilar Insufficiency / etiology

Methods: We conducted a population-based case series using administrative health care records of all Ontario residents hospitalized with VBA stroke between April 1, 1993, and March 31, 2002. Three databases were deterministically linked to extract the relevant information. We describe the demographic, health care utilization, and comorbidities of VBA patients.

Results: Ninety-three VBA stroke cases consulted a chiropractor during the year before their stroke. The mean age was 57.6 years (SD, 16.1), and 50% were female. Most cases had consulted a medical doctor during the year before their stroke, and 75.3% of patients had at least one cerebrovascular comorbidity. The 3 most common comorbidities were neck pain and headache (prevalence, 66.7%; 95% confidence interval [CI], 57.0%-76.3%), diseases of the circulatory system (prevalence, 63.4%; 95% CI, 54.8%-74.2%), and diseases of the nervous system and sense organs (prevalence, 47.3%; 95% CI, 38.7%-58.1%).

Conclusions: Our population-based analysis suggests that VBA stroke patients who consulted a chiropractor the year before their stroke are older than previously documented in clinical case series. We did not find that women were more commonly affected than men. Moreover, we found that most patients had at least one cardio- or cerebrovascular comorbidity. Our analysis suggests that relying on case series or surveys of health care professionals may provide a biased view of who develops a VBA stroke.

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• Boyle E
• Côté P
• Grier AR
• Cassidy JD

• Chiropractic / statistics and numerical data / Canada
• Iatrogenic Disease
• Manipulation, Chiropractic / statistics and numerical data
• Stroke / Canada
• Stroke / epidemiology
• Vertebrobasilar Insufficiency / epidemiology

OBJECTIVES: To determine the annual incidence of hospitalized vertebrobasilar artery (VBA) stroke and chiropractic utilization in Saskatchewan and Ontario between 1993 and 2004. To determine whether at an ecological level, the incidence of VBA stroke parallels the incidence of chiropractic utilization.

SUMMARY OF BACKGROUND DATA: Little is known about the incidence and time trends of VBA stroke diagnoses in the population. Chiropractic manipulation to the neck is believed to be a risk factor for VBA stroke. No study has yet found an association between chiropractic utilization and VBA diagnoses at the population level.

METHODS: All hospitalizations with discharge diagnoses of VBA stroke were extracted from administrative databases for Saskatchewan and Ontario. We included incident cases that were diagnosed between January 1993 and December 2004 for Saskatchewan and from April 1993 to March 2002 for Ontario. VBA cases that had previously been hospitalized for any stroke or transient ischemic attack (TIA) were excluded. Chiropractic utilization was measured using billing data from Saskatchewan Health and Ontario Health Insurance Plan. Denominators were derived from Statistics Canada's annual population estimates.

RESULTS: The incidence rate of VBA stroke was 0.855 per 100,000 person-years for Saskatchewan and 0.750 per 100,000 person-years for Ontario. The annual incidence rate spiked dramatically with a 360% increase for Saskatchewan in 2000. There was a 38% increase for the 2000 incidence rate in Ontario. The rate of chiropractic utilization did not increase significantly during the study period.

CONCLUSION: In Saskatchewan, we observed a dramatic increase in the incidence rate in 2000 and there was a corresponding relatively small increase in chiropractic utilization. In Ontario, there was a small increase in the incidence rate; however, chiropractic utilization decreased. At the ecological level, the increase in VBA stroke does not seem to be associated with an increase in the rate of chiropractic utilization.

This abstract is reproduced with the permission of the publisher. Click on the above link for the PubMed record; full text by subscription.
Republished from: Spine 2008 Feb 15;33(4 Suppl):S170-175. Free full text is available through PubMed Central.

• Cassidy JD
• Boyle E
• Côté P
• Yaohua H
• Hogg-Johnson S
• Silver FL
• Bondy SJ

• Headache
• Iatrogenic Disease / epidemiology
• Neck Pain
• Primary Health Care
• Risk Factors
• Stroke / epidemiology
• Vertebrobasilar Insufficiency / epidemiology

OBJECTIVE: To investigate associations between chiropractic visits and vertebrobasilar artery (VBA) stroke and to contrast this with primary care physician (PCP) visits and VBA stroke.

SUMMARY OF BACKGROUND DATA: Chiropractic care is popular for neck pain and headache, but may increase the risk for VBA dissection and stroke. Neck pain and headache are common symptoms of VBA dissection, which commonly precedes VBA stroke.

METHODS: Cases included eligible incident VBA strokes admitted to Ontario hospitals from April 1, 1993 to March 31, 2002. Four controls were age and gender matched to each case. Case and control exposures to chiropractors and PCPs were determined from health billing records in the year before the stroke date. In the case-crossover analysis, cases acted as their own controls.

RESULTS: There were 818 VBA strokes hospitalized in a population of more than 100 million person-years. In those aged <45 years, cases were about three times more likely to see a chiropractor or a PCP before their stroke than controls. Results were similar in the case control and case crossover analyses. There was no increased association between chiropractic visits and VBA stroke in those older than 45 years. Positive associations were found between PCP visits and VBA stroke in all age groups. Practitioner visits billed for headache and neck complaints were highly associated with subsequent VBA stroke.

CONCLUSION: VBA stroke is a very rare event in the population. The increased risks of VBA stroke associated with chiropractic and PCP visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke. We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care.

This abstract is reproduced with the permission of the publisher. Click on the above link for the PubMed record; full text by subscription. Republished from: Spine 2008 Feb 15;33(4 Suppl):S176-183. Free full text is available through PubMed Central.