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Table 3 Agreement and reliability indices of objective or patient-reported outcome measures

From: Minimal detectable change for mobility and patient-reported tools in people with osteoarthritis awaiting arthroplasty

  Week 1 mean (sd) Week 2 mean (sd) Difference mean (sd) SEM (95% CI) 90% confidence in score MDC90 MDC95 CV%
Knee         
6MWT (m) n = 72 344.9 (105.6) 348.4 (102.3) -3.5 (40.3) 28.5 (24.5 to 34.1) 46.9 66.3 79.0 8
TUG* (s), n = 74 12.7 (4.7) 13.1 (5.4) -0.4 (3.7) NA NA ±30.8% ±36.7% 13
VAS Pain (cm), n = 71 6.8 (2.0) 6.8 (1.9) 0.1 (1.6) 1.0 (0.9 to 1.2) 1.7 2.4 2.8 15
KOOS, n = 68         
Pain 39.0 (18.7) 36.7 (18.2) 2.3 (10.3) 7.3 (6.2 to 8.8) 12.0 17.0 20.2 19
Symptoms 38.8 (19.2) 39.1 (18.8) -0.4 (12.3) 8.7 (7.4 to 10.5) 40.0 20.2 24.1 22
ADL 43.8 (18.6) 40.2 (19.1) 3.6 (10.6)# 7.5 (6.4 to 9.0) 12.3 17.4 20.8 17
QOL 21.7 (7.7) 23.8 (18.8) -2.7 (13.8) 9.6 (8.2 to 11.6) 15.9 22.4 26.6 44
Hip         
6MWT (m), n = 54 339.8 (107.8) 347.3 (105.3) -7.5 (41.6) 29.4 (24.7 to 36.3) 57.7 68.5 81.5 9
TUG* ( s), n = 56 14.0 (7.2) 13.8 (6.6) 0.13 (3.6) NA NA ±37.5% ±44.6% 16
VAS Pain (cm), n = 58 7.1 (2.3) 6.8 (1.9) 0.4 (1.6) 1.2 (1.0 to 1.4) 1.9 2.7 3.3 17
HOOS, n = 56         
Pain 36.0 (20.9) 34.4 (20.6) 1.6 (11.0) 7.8 (6.6 to 9.6) 12.8 18.1 21.6 22
Symptoms 42.7 (19.4) 38.1 (21.8) 4.6 (11.6)# 8.2 (6.9 to 10.1) 13.5 19.2 22.7 19
ADL 36.7 (20.9) 34.9 (19.7) 1.8 (9.0) 6.4 (5.4 to 7.8) 10.5 14.8 17.7 17
QOL 20.4 (20.2) 21.8 (21.6) -1.4 (12.5) 8.8 (7.5 to 10.9) 14.6 20.6 24.4 43
  1. Key: SEM, standard error of measurement with 95% confidence level; MDC90 and MDC95, minimal detectable change at the 90% and 95% confidence level; CV%, co-efficient of variation per cent; 6MWT, six-minute walk test; TUG, timed up-and-go; VAS, visual analogue scale; KOOS, Knee Injury and Osteoarthritis Outcome Score; HOOS, Hip Disability and Osteoarthritis Outcome Score; ADL, activities of daily living; QOL, quality of life; NA, not applicable (The SEM for TUG is not provided as it is not derived using the same formula due to its skewed distribution); *TUG data were log-transformed - the corresponding MDC90 and MDC95 are then interpreted as 90% and 95% of the measurements being within a ratio of the original measurement. Note, average Week 1 6MWT above slightly differs from average Week 1 reported for the comparison between practise and official Week 1 as people who did not have a practise test are included in the average for Week 1 above; #, significantly different, p < 0.05.