Instruments yielded by cluster analysis and their corresponding domains, with median/mean scores reported. Values in square brackets signify items no longer considered relevant to that disease.
| Domain | Instruments | CTD-ILD Median/Mean | IPF Median/Mean |
|---|---|---|---|
| Dyspnea | Borg Dyspnea Index | 7.0/6.9 | 7.0/7.0 |
| Dyspnea 12 | [7.0/6.6] | 7.0/6.7 | |
| Medical Research Council (MRC) Breathlessness (Chronic Dyspnea) | 7.0/7.0 | 7.0/7.1 | |
| Scale or the Modified MRC Dyspnea Scale | |||
| Borg Dyspnea Index, pre- and post-exercise | 7.0/7.0 | [7.0/7.1] | |
| Health-related quality of life (HRQOL) | Medical Outcome Study Short Form-36 Questionnaire | 7.0/7.3 | 7.0/7.3 |
| St. George’s Dyspnea Respiratory Questionnaire | [7.0/6.6] | 7.0/6.8 | |
| Visual analog scale of patient assessment of disease activity | 7.0/6.8 | 7.0/6.7 | |
| Ability to carry out activities of daily living | 7.0/6.8 | Lost Tier 1 | |
| Health Assessment Questionnaire Disability Index | 7.0/7.0 | Lost Tier 1 | |
| Lung imaging | Extent of honeycombing on HRCT | 7.0/7.1 | 8.0/7.4 |
| Extent of reticulation on HRCT | [7.0/6.9] | 7.0/6.9 | |
| Extent of ground glass opacities on HRCT | 7.0/7.2 | [7.0/6.7] | |
| Overall extent of interstitial lung disease on HRCT | 8.0/7.7 | 8.0/7.7 | |
| Lung physiology/function | Supplemental oxygen requirement | 7.0/7.3 | 8.0/7.5 |
| Forced vital capacity on spirometry | 8.0/8.3 | 9.0/8.3 | |
| Diffusion capacity of lung for carbon monoxide | 8.0/7.9 | 8.0/7.9 | |
| 6-MWT with maximal desaturation on pulse oximetry | 7.0/6.8 | 7.0/7.0 | |
| 6-MWT for distance | [7.0/6.5] | 7.0/7.0 | |
| Survival | Time to decline in forced vital capacity | 7.0/7.3 | 7.0/7.0 |
| Progression-free survival | 8.0/8.2 | 8.0/8.3 | |
| Time to death | 7.0/7.1 | 8.0/7.3 |
6-MWT: 6-minute walk test; CTD-ILD: connective tissue disease-related interstitial lung disease; IPF: idiopathic pulmonary fibrosis; HRCT: high-resolution computed tomography.