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. Author manuscript; available in PMC: 2014 Feb 23.
Published in final edited form as: Crit Care Med. 2010 Mar;38(3):855–860. doi: 10.1097/CCM.0b013e3181cd10c7

Table 4.

Agreement between patient and proxy baseline quality of life scores

SF-36 domain State Changea Kappab [95% CI] Weighted Kappab,d [95% CI] MCID (30) MCID Kappac [95% CI] MCID Weighted Kappac, d [95% CI]
Physical Function 5.0 0.16 [0.11, 0.21] 0.36 [0.24, 0.47] 10.0 0.21 [0.14, 0.29] 0.36 [0.25, 0.48]
Role Physical 6.25 0.13 [0.08, 0.18] 0.38 [0.27, 0.50] 12.5 0.17 [0.09, 0.24] 0.39 [0.27, 0.51]
Bodily Pain 10.0 0.08 [0.02, 0.14] 0.34 [0.22, 0.46] 10.0 0.08 [0.02, 0.14] 0.34 [0.22, 0.46]
General Health 5.0 0.02 [−0.01, 0.05] 0.35 [0.25, 0.45] 10.0 0.10 [0.03, 0.17] 0.37 [0.26, 0.47]
Vitality 6.25 0.07 [0.03, 0.11] 0.32 [0.23, 0.42] 12.5 0.17 [0.09, 0.25] 0.35 [0.24, 0.45]
Social Function 12.5 0.18 [0.12, 0.25] 0.34 [0.23, 0.46] 12.5 0.18 [0.12, 0.25] 0.34 [0.23, 0.46]
Role Emotional 8.3 0.16 [0.09, 0.24] 0.40 [0.28, 0.52] 8.3 0.16 [0.09, 0.23] 0.40 [0.28, 0.52]
Mental Health 5.0 0.06 [0.02, 0.10] 0.41 [0.31, 0.51] 10.0 0.17 [0.09, 0.24] 0.43 [0.33, 0.54]

Abbreviations: CI – confidence interval; COPD – chronic obstructive pulmonary disease; MCID – minimal clinically important difference; QOL – quality of life; SF-36 – Short-Form 36

a

A state change is defined as the smallest possible change in score based on a 1 unit change in response for 1 question within a domain

b

Perfect agreement is defined as having an absolute difference between the patient and proxy score of less than or equal to the state change

c

Perfect agreement is defined as having an absolute difference between the patient and proxy score of less than the MCID

d

For the weighted kappa, weights were assigned using linear weighting which assigns a weight of 1 for perfect agreement and 0 for the largest possible disagreement, with other weights of misclassifications determined linearly.(34)