LAWM Speth* MD, Physician in Physical and Rehabilitation Medicine, Rehabilitation Foundation Limburg (SRL), location Franciscusoord, Valkenburg;
P Leffers MSc, Clinical Epidemiologist, Department of Epidemiology, Maastricht University, Maastricht;
YJM Janssen-Potten PhD, Movement Scientist, Institute for Rehabilitation Research (IRV), Hoensbroek;
JSH Vles MD PhD, Child Neurologist, Academic Hospital Maastricht (azM), Maastricht, the Netherlands.
*Correspondence to first author at SRL, location Franciscusoord, Onderstestraat 29, 6301 KA Valkenburg, the Netherlands.
E-mail: l.speth@srl.nl