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Table 3 Area under the curve for ROC curves as well as slight or more, moderate or more and much better important difference for both the absolute and relative changes for the 6MWT

From: Minimal important improvement thresholds for the six-minute walk test in a knee arthroplasty cohort: triangulation of anchor- and distribution-based methods

Important change Max negative and positive changes in distancea AUC (95 % CI) Youden’s method Sensitivity (95 % CI)b Specificity (95 % CI)b 80 % Specificity method Sensitivity (95 % CI)b Specificity (95 % CI)b
10 weeks Absolute
 Slight or more (n = 140) −148.0 m to 290.0 m 70.1 % (55.58, 84.7) 11.5 m 70.2 (62.41, 78.39) 66.7 (40, 86.67) 53.0 m 48.9 (41.13, 57.45) 80.0 (60, 100)
 Moderate or more (n = 128) −148.0 m to 290.0 m 72.3 % (51.15, 83.35) 11.5 m 74.4 (66.67, 82.95) 70.4 (51.85, 85.19) 53.0 m 51.9 (42.64, 60.47) 81.4 (66.67, 92.59)
 Much better (n = 85) −148.0 m to 252.0 m 62.8 % (53.85, 71.78) 11.5 m 79.1 (70.93, 87.21) 48.6 (36.39, 60) 106.5 m 29.1 (19.16, 38.37) 80.0 (71.43, 88.57)
10 weeks Relative
 Slight or more (n = 140) −92.6 to 486.0 % 67.3 % (51.21, 83.44) 5.1 % 66.7 (58.16, 74.13) 66.7 (40, 86.67) 15.1 % 49.7 (40.43, 58.16) 80.0 (60, 100)
 Moderate or more (n = 128) −92.6 to 486.0 % 70.7 % (59.05, 82.32) 5.1 % 70.5 (62.02, 78.29) 70.4 (51.85, 85.19) 15.5 % 48.8 (40.31, 56.59) 81.5 (66.67, 94.54)
 Much better (n = 85) −92.6 to 486.0 % 60.7 % (51.53, 69.9) 5.7 % 54.3 (44.29, 65.71) 70.5 (63.95, 83.17) 49.1 % 23.3 (15.12, 32.56) 80.0 (70.68, 88.57)
26 weeks Absolute
 Slight or more (n = 188) −242.3 m to 370.0 m 72.4 % (62.05, 82.7) 26 m 72.9 (66.21, 79.26) 65.2 (45.54, 82.61) 64.5 m 50.0 (43.09, 56.91) 82.6 (67.28, 95.65)
 Moderate or more (n = 179) −242.3 m to 370.0 m 70.6 % (60.33, 80.94) 6.5 m 81.6 (75.98, 87.15) 56.3 (38.98, 71.88) 71.0 m 48.0 (41.05, 55.31) 81.3 (67.28, 95.65)
 Much better (n = 143) −194.0 m to 370.0 m 64.7 % (56.59, 72.77) 8.5 m 84.4 (78.01, 90.07) 41.4 (31.43, 54.29) 110.5 m 35.5 (27.66, 43.63) 81.4 (72.86, 90)
26 weeks Relative
 Slight or more (n = 188) −93 to 515.2 % 71.7 % (60.64, 82.79) 11.3 % 65.4 (58.51, 72.09) 73.9 (56.52, 89.24) 18.3 % 52.1 (45.74, 59.04) 82.6 (67.28, 95.65)
 Moderate or more (n = 179) −93.2 to 515.2 % 69.6 % (58.74, 80.4) 1.5 % 82.1 (76.54, 87.71) 56.3 (37.5, 71.88) 27.9 % 40.78 (33.78, 48.6) 81.3 (65.62, 93.75)
 Much better (n = 143) −91.3 to 515.2 % 63.4 % (55.07, 71.78) 1.54 % 85.1 (79.06, 90.78) 41.4 (30, 52.86) 61.0 % 21.3 (14.18, 27.66) 84.3 (74.29, 84.29)
  1. aChange in distance from pre-operative 6MWT. Negative integers and percentages <100 % indicate 6MWT is less than preoperative values. Positive integers and percentages >100 % indicate farther distance
  2. bSpecificity or Sensitivity values ≤50.0 indicate that the important improvement threshold is no better than chance at classifying individuals as improved or not