Table 1.

Methodological criteria of the checklist of van Tulder et al. (2003) [15]

Aspect	Description	Item
Randomisation	Is a valid randomisation technique applied	A
Allocation concealment	Was the treatment allocation concealed	B
Prognostic factors	Are the patient groups comparable on prognostic factors	C
Patient blinding	Is the patient blinded for the treatment	D
Surgeon blinding	Is the surgeon blinded for the treatment	E
Outcome assessor blinding	Is the outcome assessor blinded for the treatment allocation	F
Co-interventions	Are the co-interventions described in sufficient detail	G
Compliance	Is the compliance acceptable	H
Drop-out	Is the drop-out rate given and acceptable	I
Timing	Is the timing of the outcome assessments comparable between groups and consistent within groups	J
Intention to treat	Is an intention to treat analysis given	K
Homogeneity	Is the patient group homogeneous on prognostic factors	L