[1] Univ Ghent, Dept Publ Hlth, Interuniv Ctr Hlth Econ Res I CHER, Ghent, Belgium
[2] Vrije Univ Brussel, Dept Publ Hlth, Interuniv Ctr Hlth Econ Res I CHER, Brussels, Belgium
[3] Katholieke Univ Leuven, Dept Pharmaceut & Pharmacol Sci, Leuven, Belgium
[4] Natl Ctr COME Collaborat, Practice & Promot Vzw CORPP, Commiss Osteopath Res, Mechelen, Belgium