Table 4

Quality assessment

External validity		Internal validity				Total
Author	Subjects representative?	Determinants accurate?	Statistical test appropriate?	Losses to follow-up taken into account?	Adjustment for confounding?	High quality
Gibbs et al9	Unable to determine^*	Yes	Yes	Yes	No	3
Koulouris et al17	Yes	Yes	Yes	Yes	No	4
Malliaropoulos et al10	Yes	Yes	Yes	Yes	No	4
Sherry and Best19	No	Unable to determine^†	Yes	No	No	1
Verrall et al18	Yes	Yes	Yes	Yes	No	4

↵* Study does not report the source population from where the patients were selected.
↵† Determinants measured were the rehabilitation programme and functional tests; it was unable to determine whether this was performed accurately.