Table 3. Correlation between health-related quality of life scores and disease severity measures (N=99).
| Variables | EQ5D-3L utility value | EQ5D-3L VAS | K-BILD total | K-BILD breath | K-BILD psych | K-BILD chest | mMRC score | FVC† | DLCO† | CCI |
|---|---|---|---|---|---|---|---|---|---|---|
| EQ5D-3L utility value | 1 | |||||||||
| EQ5D-3L VAS | 0.530**& | 1 | ||||||||
| K-BILD total | 0.538**& | 0.471**& | 1 | |||||||
| K-BILD breath | 0.547**& | 0.470**& | 0.950**&& | 1 | ||||||
| K-BILD psych | 0.470**& | 0.420**& | 0.952**&& | 0.830**&& | 1 | |||||
| K-BILD chest | 0.489**& | 0.382**& | 0.840**&& | 0.772**&& | 0.756**&& | 1 | ||||
| mMRC score | −0.535**& | −0.525**& | −0.585**& | −0.581**& | −0.535**& | −0.475**& | 1 | |||
| FVC† | 0.336**& | 0.266** | 0.396**& | 0.389**& | 0.375**& | 0.213* | −0.527**& | 1 | ||
| DLCO† | 0.218* | 0.275** | 0.414**& | 0.448**& | 0.360**& | 0.260** | −0.437**& | 0.569**& | 1 | |
| CCI | −0.187 | −0.220* | −0.185 | −0.228* | −0.162 | −0.128 | 0.314**& | −0.013 | −0.185 | 1 |
Correlation 0.8= very strong, 0.6–0.79= strong, 0.3–0.59= moderate, <0.3= weak. &&, highlight very strong or strong correlation; &, moderate correlation. *, correlation is significant at the 0.05 level (2-tailed); **, correlation is significant at the 0.01 level (2-tailed); †, percentage predicted values. EQ5D-3L, EuroQol 5-dimension 3 level version; K-BILD, King’s brief interstitial lung disease questionnaire; K-BILD breath, K-BILD breathlessness & activities; K-BILD psych, K-BILD psychological; K-BILD chest, K-BILD chest symptoms; mMRC, modified medical research council dyspnoea scale; FVC, forced vital capacity; DLCO, carbon monoxide diffusing capacity; CCI, Charlson comorbidity index; VAS, visual analogue scale.