Examining vertebrobasilar artery stroke in two Canadian provinces

Area of Science:

• Epidemiology
• Neurology
• Public Health

Background:

• Limited data exists on vertebrobasilar artery (VBA) stroke incidence and trends.
• Neck manipulation by chiropractors is a suspected risk factor for VBA stroke.
• No population-level studies have demonstrated an association between chiropractic use and VBA diagnoses.

Purpose of the Study:

• To determine the annual incidence of hospitalized VBA stroke in Saskatchewan and Ontario from 1993-2004.
• To assess chiropractic utilization rates in these provinces during the same period.
• To investigate if VBA stroke incidence parallels chiropractic utilization at an ecological level.

Main Methods:

• An ecological study utilizing administrative databases for VBA stroke hospitalizations in Saskatchewan and Ontario.
• Incident VBA stroke cases were identified between 1993-2004 (Saskatchewan) and 1993-2002 (Ontario), excluding prior stroke/TIA patients.
• Chiropractic utilization data was sourced from provincial billing records, with population denominators from Statistics Canada.

Main Results:

• VBA stroke incidence was 0.855/100,000 person-years (Saskatchewan) and 0.750/100,000 person-years (Ontario).
• Saskatchewan experienced a 360% increase in VBA stroke incidence in 2000, while Ontario saw a 38% increase.
• Chiropractic utilization rates did not significantly increase during the study period in either province.

Conclusions:

• A significant increase in VBA stroke incidence in Saskatchewan in 2000 was not mirrored by a substantial rise in chiropractic utilization.
• In Ontario, a slight increase in VBA stroke incidence coincided with a decrease in chiropractic utilization.
• Ecological analysis does not support a link between increased VBA stroke incidence and increased chiropractic utilization.