[1
]
A.J.H. Verwoerd, MD, PhD, Department of General Practice, Erasmus MC University Medical
Center, PO Box 2040, 3000 CA Rotterdam, the Netherlands. j.verwoerd@erasmusmc.nl.
[2
]
P.A.J. Luijsterburg, PhD, Department of General Practice, Erasmus MC University Medical
Center.
[3
]
B.W. Koes, PhD, Department of General Practice, Erasmus MC University Medical Center.
[4
]
A. el Barzouhi, MD, PhD, Department of Neurosurgery, Leiden University Medical Center,
Leiden, the Netherlands.
[5
]
A.P. Verhagen, PhD, Department of General Practice, Erasmus MC University Medical
Center.