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Table 1 A priori responsiveness hypotheses

From: One-minute stair climbing, 50-foot walk, and timed up-and-go were responsive measures for patients with chronic low back pain undergoing lumbar fusion surgery

1.

The change scores (differences between baseline and 6-month assessments) of a physical capacity task will be able to distinguish between patients with and without meaningful improvementa as classified by a construct-specific GPE scale (area under the ROC curve ≥0.70) [24, 37, 56].b

2.

The change scores of a physical capacity task will yield greater misclassifications of improved and unchanged patients on a ROC curve when that classification is based on a generic GPE scale rather than construct-specific GPE scales [24, 37, 56].b

3.

The change scores of the four physical capacity tasks will be correlated ≥0.50 to each other in the expected direction [17, 22].c

4.

The correlations between change scores of physical capacity tasks and the ODI will be at least 0.10 weaker than the correlations between the change scores among the physical capacity tasks themselves [13, 20].

5.

The correlations between change scores of a physical capacity task and VAS on back pain intensity will be at least 0.10 weaker than the correlations between change scores of the physical capacity task and the ODI [13, 17].

  1. GPE Global perceived effect, ODI Oswestry Disability Index, ROC Receiver operating characteristic, VAS Visual analog scale
  2. aImproved patients were considered to be those who had scored the response alternatives “much better” or “better” on the construct-specific GPE scales and unchanged patients were those who had scored response alternatives “somewhat better,” “unchanged,” or “somewhat worse”
  3. bFor timed up-and-go, Hypotheses 1 and 2 were tested separately for the construct-specific GPE scales on walking and chair rise, respectively, since the task includes both of these activities
  4. cThe expected direction depends on whether a negative or positive change score of a physical capacity task indicates an improvement or deterioration. The correlations between five-minute walk and 1-min stair climbing as well as the correlations between 50-ft walk and timed up-and-go were expected to be positive. The other possible correlations among the four physical capacity tasks were expected to be negative