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Table 2 Estimated Regression-to-the-mean

From: Identification of pain categories associated with change in pain in patients receiving placebo: data from two phase 3 randomized clinical trials in symptomatic knee osteoarthritis

WOMAC sub-score SD σ2b σ2w Estimated RTM effect from BL to Y2 (%) Pain change from BL to Y2 adjusted for estimated RTM effect (%)
Question 1: Walking on flat surface 56 1602.5 1533.5 32.6 0.9
Question 2: On stairs 38 735.0 709.0 26.0 −10.9
Question 3: Lying in bed 80 3872.0 2528.0 33.7 11.2
Question 4: Sitting or lying 69 2551.9 2209.1 35.6 6.3
Question 5: Standing 57 1614.8 1634.3 33.9 −0.1
Questions 1, 2, and 5: Weight-bearing 39 734.6 786.4 27.8 −15,4
Questions 3 and 4: Non-weight-bearing 65 2433.6 1791.4 31.2 −4.6
  1. The percentage of RTM of the Target knee as estimated using the method of Barnett et al. [24]. Calculation of σ2w was based on within patient data from screening visit and subsequent baseline visit, between 1 and 3 weeks apart. σ2b: Between patient-variance. σ2w: Within patient-variance. BL Baseline. Y2 Year 2, RTM Regression to the mean