Table 5: Adjusted* mean change in outcome from referral to immediately preoperatively for the 2 wait time groups.
| Outcome measure | Wait time; mean change in score (SE)† | Mean difference in change (95% CI) | |
|---|---|---|---|
| Shorter (≤ 12 mo) | Longer (> 12 mo) | ||
| SF-36 PC summary score | -0.8 (0.9) | -1.3 (0.9) | 0.5 (-1.5 to 2.6) |
| SF-36 MC summary score | -0.9 (1.5) | -1.6 (1.6) | 0.6 (-2.8 to 4.1) |
| ODI score | 6.6 (1.5) | 3.9 (1.6) | 2.7 (-0.9 to 6.2) |
| ZCQ score | 0.2 (0.1) | 0.2 (0.1) | 0.01 (-0.2 to 0.2) |
| Back pain score | 0.7 (0.5) | 0.6 (0.6) | 0.1 (-1.0 to 1.2) |
| Leg pain score | 0.4 (0.3) | 0.2 (0.4) | 0.3 (-0.4 to 1.0) |
Note: CI = confidence interval, MC = mental component, ODI = Oswestry Disability Index, PC = physical component, SE = standard error, SF-36 = 36-Item Short-Form Health Survey, ZCQ = symptom severity scale of the Zurich Claudication Questionnaire.
*Adjusted for age, surgeon, duration of symptoms at consultation and surgery type.
†For SF-36 PC summary score and MC summary score, a negative change indicates deterioration. For ODI score, ZCQ score, back pain score and leg pain score, a positive change indicates deterioration.