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Table 5 Comparison of relative validity (RV) of QDIS-7 and generic measures in discriminating across severity levels, five disease groups

From: Standardizing disease-specific quality of life measures across multiple chronic conditions: development and initial evaluation of the QOL Disease Impact Scale (QDIS®)

Disease/Measure

Mean (SD) by Self-Evaluated Severitya

F-ratio

RVb

95 % CIc

Mild

Moderate

Severe

Arthritis

(N = 688)

(N = 564)

(N = 214)

   

 QDIS-7d

49.2 (6.88)

57.4 (5.83)

64.9 (5.81)

586.27

1.00

 

 SF-8 PCSe

48.1 (7.60)

40.9 (8.65)

31.2 (8.22)

383.73

0.65

(0.56,0.76)

 SF-8 MCSe

51.8 (8.08)

48.8 (10.19)

44.7 (11.40)

49.19

0.08

(0.05,0.12)

CKD

(N = 189)

(N = 56)

(N = 33)

   

 QDIS-7

44.7 (6.96)

53.3 (7.72)

61.3 (8.40)

87.99

1.00

 

 SF-8 PCS

42.2 (11.10)

37.3 (10.61)

33.3 (7.50)

12.41

0.14

(0.06,0.26)

 SF-8 MCS

50.4 (9.43)

45.6 (11.82)

44.4 (11.33)

8.15

0.09

(0.02,0.20)

Cardiovascular

(n = 469)

(n = 107)

(n = 35)

   

 QDIS-7

48.5 (8.83)

58.9 (6.66)

65.6 (5.60)

123.29

1.00

 

 SF-8 PCS

41.8 (10.25)

34.2 (8.55)

30.4 (7.21)

43.32

0.35

(0.24,0.50)

 SF-8 MCS

49.8 (9.70)

46.5 (10.70)

39.1 (12.74)

21.47

0.17

(0.07,0.30)

Diabetes

(N = 870)

(N = 317)

(N = 58)

   

 QDIS-7

45.3 (6.42)

51.5 (7.21)

59.0 (5.85)

196.01

1.00

 

 SF-8 PCS

48.4 (8.76)

44.4 (9.93)

40.6 (11.03)

36.59

0.19

(0.11,0.28)

 SF-8 MCS

51.9 (8.08)

48.4 (9.75)

42.6 (11.49)

44.33

0.23

(0.13,0.34)

Respiratory

(N = 1106)

(N = 297)

(N = 109)

   

 QDIS-7

44.7 (7.10)

56.4 (6.71)

64.3 (7.07)

622.23

1.00

 

 SF-8 PCS

48.1 (9.46)

41.4 (10.20)

33.4 (10.84)

149.30

0.24

(0.18,0.30)

 SF-8 MCS

49.5 (9.34)

46.4 (11.65)

42.2 (12.06)

32.74

0.05

(0.03,0.08)

  1. Abbreviations: CKD chronic kidney disease
  2. aSeverity defined as Mild (None, Mild), Moderate, or Severe (Severe, Very Severe) in response to item How would you rate the severity of your < condition > in the past 4 weeks?
  3. bRelative validity (RV) is computed as the ratio of the comparator F-statistic over the QDIS-7 F-statistic
  4. cComparator confidence intervals (CI) estimated using bootstrap
  5. dQDIS-7 scored so a higher score equals worse health
  6. eNorm-based scoring of SF-8 Health Survey summary measures based on a representative probability sample of the US general household population surveyed in 2011, norms (mean = 50, SD = 10) scored so a higher score equals better health