Relationship of QLF extent (%) and volume (mL) with the anchor-based MCID of SGRQ and FVC using Jaeschke’s method
| Anchor | Adjusted corresponding QLF values of thresholds compared with stable condition* | ||||
| Week 24 | Week 48 | ||||
| SGRQ change | |||||
| SGRQ | Whole lung | Improved† (N=48) | Worsened† (N=41) | Improved† (N=41) | Worsened† (N=42) |
| QLF, % | ≤0.5 | ≥4.4‡ | ≤ –2.8‡ | ≥2.3 | |
| 95% CI | (−1.5, 2.5) | (2.3, 6.5) | (−5.4, −0.2) | (−0.3, 4.9) | |
| QLF, mL | ≤10 | ≥91‡ | ≤ –54 | ≥81‡ | |
| 95% CI | (−38, 58) | (41, 141) | (−118, 9) | (18, 144) | |
| ppFVC change | |||||
| Improved† (N=20) | Worsened† (N=49) | Improved† (N=20) | Worsened† (N=53) | ||
| ppFVC | QLF, % | ≤–2.0 | ≥3.6‡ | ≤–2.1 | ≥4.3‡ |
| 95% CI | (−4.5, 0.6) | (1.7, 5.4) | (−5.1, 0.8) | (2.1, 6.4) | |
| QLF, mL | ≤–56 | ≥65‡ | ≤–65 | ≥108‡ | |
| 95% CI | (−118, 7) | (20, 110) | (−143, 13) | (51, 164) | |
*Shifted by the mean changes at ±5 points SGRQ and ±3.4% ppFVC; stated with two significant figures.
†Worsened: SGRQ change ≥5 points or ppFVC change ≤3.4%; stable: SGRQ change between –5 and 5 points or ppFVC change between –3.4% and 3.4%; improved: SGRQ change ≤–5 points or ppFVC change ≥3.4%.
‡Two 95% CIs of the difference between the improved and stable groups and the difference between worse and stable groups are not overwrapped. 95% CIs were obtained from a one-way ANOVA model in the model. Comparisons are obtained from the same model using the least squares means (LSMEANS) statement.
ANOVA, analysis of variance; FVC, forced vital capacity; MCID, minimum clinically important difference; ppFVC, percent-predicted forced vital capacity; QLF, Quantitative Lung Fibrosis score; SGRQ, St. George’s Respiratory Questionnaire.