Table 2.

The difference in standard score between the control group and the treatment group (responsiveness), in the variables of interest and WOMAC pain subscale, at different timepoints in the study. Values are mean (95% CI) and p value.

OutcomeWOMAC Pain Subscale Between-groups Standard Score Difference (reference)*
Week 2Week 4Week 8Week 12Week 16
WOMAC pain subscale (reference)0.02 (−0.16 to 0.20), 0.85−0.37 (−0.55 to −0.18), < 0.001−0.44 (−0.63 to −0.26), < 0.001−0.38 (−0.57 to −0.19), < 0.001−0.26 (−0.45 to −0.07), 0.01
OutcomeDifference from WOMAC Pain Subscale, in Standard Score Units**
Week 2Week 4Week 8Week 12Week 16
IndividualWOMAC physical function subscale−0.10 (−0.25 to 0.06), 0.22−0.04 (−0.21 to 0.12), 0.59−0.01 (−0.18 to 0.16), 0.90−0.04 (−0.22 to 0.15), 0.70−0.07 (−0.25 to 0.11), 0.46
OutcomesWOMAC stiffness subscale−0.22 (−0.38 to −0.07), 0.01−0.15 (−0.31 to 0.01), 0.07−0.10 (−0.27 to 0.06), 0.22−0.16 (−0.34 to 0.02), 0.09−0.17 (−0.35 to 0.01), 0.07
No. RM pills taken/day−0.10 (−0.26 to 0.05), 0.200.04 (−0.13 to 0.20), 0.660.13 (−0.03 to 0.30), 0.120.13 (−0.05 to 0.31), 0.170.02 (−0.17 to 0.20), 0.85
CompositeComposite 1: WOMAC pain and no. RM pills−0.03 (−0.19 to 0.13), 0.71−0.04 (−0.21 to 0.12), 0.600.00 (−0.17 to 0.16), 0.96−0.01 (−0.19 to 0.18), 0.94−0.04 (−0.22 to 0.15), 0.69
OutcomesComposite 2: WOMAC P, S, F−0.11 (−0.26 to 0.05), 0.17−0.07 (−0.24 to 0.09), 0.38−0.05 (−0.21 to 0.12), 0.57−0.07 (−0.26 to 0.11), 0.42−0.09 (−0.27 to 0.10), 0.36
Composite 3: WOMAC P, S, F, and no. RM pills−0.11 (−0.27 to 0.05), 0.17−0.09 (−0.25 to 0.07), 0.28−0.05 (−0.22 to 0.12), 0.56−0.09 (−0.27 to 0.09), 0.34−0.09 (−0.28 to 0.09), 0.33

  • ↵* Indicates the difference in standard score between placebo and treatment in the WOMAC pain subscale, at each study timepoint. Negative values indicate greater pain reduction in the treatment group than the control group, and vice versa.

  • ↵** Indicates how the between-groups difference in the other pain outcomes compared to the WOMAC pain subscale. There was an average greater reduction in pain in the treatment group compared to the control group in the WOMAC function subscale compared to the WOMAC pain subscale, in the same patients at the same timepoint, and therefore the WOMAC physical function subscale showed greater sensitivity to a change in pain at this timepoint than the WOMAC pain subscale. More negative values indicate increased sensitivity to change in the outcome shown, relative to the WOMAC pain subscale. Positive values indicate greater sensitivity to change in the WOMAC pain subscale. WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; RM: rescue medication; P, S, F: WOMAC pain, stiffness, and function subscales.