Table 5.
Comparison of relative validity (RV) of QDIS-7 and generic measures in discriminating across severity levels, five disease groups
| 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) |
Abbreviations: CKD chronic kidney disease
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?
bRelative validity (RV) is computed as the ratio of the comparator F-statistic over the QDIS-7 F-statistic
cComparator confidence intervals (CI) estimated using bootstrap
dQDIS-7 scored so a higher score equals worse health
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