Table 1

Quality assessment of included studies

Study	Quality-assessment items^a
Study	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	Overall quality
Balague et al, 199527	⁺	⁺	⁺	⁺	⁻	⁺	⁺	⁺	⁺	⁺	na	na	⁺	⁺	⁺	High
Balague et al, 199429	⁺	⁺	⁺	⁺	⁻	⁺	⁺	⁺	na	⁺	na	na	⁺	⁺	⁺	High
Campo et al, 200734	⁺	⁺	⁺	⁺	⁻	⁺	⁺	⁺	⁺	na	na	na	⁺	⁺	⁺	High
Cardol et al, 200635	⁺	⁺	⁺	⁺	⁺	⁺	⁺	⁺	⁺	na	na	na	⁺	⁺	⁺	High
Craig et al, 200224	⁺	⁺	⁺	⁺	⁻	⁺	⁺	⁺	na	⁺	na	na	⁺	⁺	⁺	High
Levy et al, 200423	⁺	⁺	⁺	⁺	⁻	⁺	⁺	⁺	⁺	⁻	na	na	⁺	⁺	⁺	High
Levy et al, 200036	⁺	⁺	⁺	⁺	⁻	⁺	⁺	⁺	⁺	na	na	na	⁺	⁺	⁺	High
Little et al, 200122	⁺	⁺	⁺	⁺	⁺	⁺	⁺	⁺	⁺	⁺	na	⁺	⁺	⁺	⁺	High

↵+ = satisfactorily presented.
↵− absent.
na = not applicable.
↵a See Appendix 1 for detailed description of quality-assessment items.