BISIMAN study: The background incidence of stroke in manipulation in the United Kingdom

Abstract

In current literature, strokes of all description have been linked with cervical manipulation. At present, there are no accurate data regarding relative risk or background incidence rates. The background rate of all types of stroke for the UK chiropractic patient population is calculated in this study. The age profiles of 728 consecutive (both new and existing) patients attending four chiropractic clinics were banded into groups to enable comparison with previous major studies of stroke incidence. The number of patients receiving chiropractic neck manipulation was calculated by multiplying the number of registered chiropractors by the known average number of cervical manipulations. These data were then used to extrapolate the expected background rate (i.e. non-causative) of stroke in the chiropractic population. Estimated number of neck manipulations annually by UK chiropractors was 4,439,800, representing 554,975 patients. Estimated number of background strokes in this population over the course of 1 year was 1645. The inferred number of background strokes within 1 and 3 days of manipulation was 36 and 108, respectively. It is not surprising that some patients presenting to neurologists with stroke have had a recent history of chiropractic cervical manipulation, owing to the high background incidence of stroke and the number manipulations performed annually. The authors propose future prospective studies to ascertain the so far un-elicited risk ratio as well as a co-ordinated neurology based education programme for the recognition of early signs of stroke in chiropractic clinics.