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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