Concurrent validity, internal reliability and repeatability of the King's Brief Interstitial Lung Disease (K-BILD) questionnaire in idiopathic pulmonary fibrosis (IPF); comparison with other interstitial lung diseases (ILDs)
| K-BILD Total score | ||
| IPF | ILD, non-IPF | |
| SGRQ Total | −0.9 | −0.9 |
| SGRQ Sym | −0.7 | −0.7 |
| SGRQ Act | −0.8 | −0.8 |
| SGRQ Imp | −0.9 | −0.9 |
| FVC % | 0.6 | 0.4 |
| TLCO % | 0.4* | 0.5 |
| Internal reliability (Cronbach’s α coefficient) | 0.9 | 0.9 |
| Repeatability (intraclass correlation coefficient) | 0.9 | 0.9 |
Data shown are Pearson's correlation coefficients unless otherwise stated. p<0.01 or *p<0.05.
FVC, forced vital capacity; SGRQ, St George's Respiratory Questionnaire; SGRQ Act, SGRQ – Activity; SGRQ Imp, SGRQ – Impact; SGRQ Sym, SGRQ – Symptoms; TLCO, diffusing capacity of the lung for carbon monoxide as % predicted.