Table 6: Pearson correlation between wait time for surgery and differences in outcome from immediately preoperatively to 6, 12 and 24 months after surgery

Outcome measure*	Time point; r
Outcome measure*	6 mo	12 mo	24 mo
SF-36 PC summary score	-0.079	0.063	0.067
SF-36 MC summary score	-0.133	-0.224‡	-0.115
ODI score	0.223‡	0.205†	0.064
ZCQ score	0.200†	0.093	0.156
Back pain score	0.077	0.079	0.102
Leg pain score	0.221‡	0.160	0.054

Note: MC = mental component, ODI = Oswestry Disability Index, PC = physical component, SF-36 = 36-item Short-Form Health Survey, ZCQ = symptom severity scale of the Zurich Claudication Questionnaire.

*Adjusted for baseline score, age, surgeon, duration of symptoms and surgery type.

†p < 0.05.

‡p < 0.01.