Competing interests
K.B.D. and L.H. and H.W.C. are supported partly by the Foundation for Chiropractic Research and Postgraduate Education; W.V.s work at the Basel Academy has been financed by the Chiropractic Knowledge Hub; S.L. and H.W.C. and K.B.D. are in private practice, treating the patients in question. No other relationships or activities that could appear to have influenced the submitted work.