Table 2.

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.

DomainInstrumentsCTD-ILD Median/MeanIPF Median/Mean
DyspneaBorg Dyspnea Index7.0/6.97.0/7.0
Dyspnea 12[7.0/6.6]7.0/6.7
Medical Research Council (MRC) Breathlessness (Chronic Dyspnea)7.0/7.07.0/7.1
Scale or the Modified MRC Dyspnea Scale
Borg Dyspnea Index, pre- and post-exercise7.0/7.0[7.0/7.1]
Health-related quality of life (HRQOL)Medical Outcome Study Short Form-36 Questionnaire7.0/7.37.0/7.3
St. George’s Dyspnea Respiratory Questionnaire[7.0/6.6]7.0/6.8
Visual analog scale of patient assessment of disease activity7.0/6.87.0/6.7
Ability to carry out activities of daily living7.0/6.8Lost Tier 1
Health Assessment Questionnaire Disability Index7.0/7.0Lost Tier 1
Lung imagingExtent of honeycombing on HRCT7.0/7.18.0/7.4
Extent of reticulation on HRCT[7.0/6.9]7.0/6.9
Extent of ground glass opacities on HRCT7.0/7.2[7.0/6.7]
Overall extent of interstitial lung disease on HRCT8.0/7.78.0/7.7
Lung physiology/functionSupplemental oxygen requirement7.0/7.38.0/7.5
Forced vital capacity on spirometry8.0/8.39.0/8.3
Diffusion capacity of lung for carbon monoxide8.0/7.98.0/7.9
6-MWT with maximal desaturation on pulse oximetry7.0/6.87.0/7.0
6-MWT for distance[7.0/6.5]7.0/7.0
SurvivalTime to decline in forced vital capacity7.0/7.37.0/7.0
Progression-free survival8.0/8.28.0/8.3
Time to death7.0/7.18.0/7.3
  • 6-MWT: 6-minute walk test; CTD-ILD: connective tissue disease-related interstitial lung disease; IPF: idiopathic pulmonary fibrosis; HRCT: high-resolution computed tomography.