Table 1– Demographic, clinical, functional and radiographic characteristics of the two cohorts# at the time of diagnosis
VariableProspective cohortRetrospective cohortp-value
Subjects n7068
M/F (% male)57/13 (81)50/18 (74)ns
Age yrs67±862±90.0011
BMI m·kg−228±427±5ns
Time to diagnosis months23±20NANA
Biopsy-based diagnosis yes/no (%)23/47 (33)22/46 (32)ns
Smokers/never-smokers (%)44/26 (63)34/34 (50)ns
Smoking pack-yrs33±1824±170.028
Concomitant emphysema yes/no (%)24/46 (34)13/55 (19)0.044
MRC dyspnoea score2.5±1.1NANA
6MWD m372±146350±116ns
6MWD % pred79±2968±240.049
PA–a,O2 mmHg32±1426±10ns
FVC % pred75±2275±21ns
DL,CO+ % pred46±1955±170.013
HRCT disease extent§ % of total lung volume36±12NANA
BAL total cell countƒ cells·mL−1596130±502073NANA
  • Data are presented as mean±sd, unless otherwise stated. M: male; F: female; BMI: body mass index; MRC: Medical Research Council; 6MWD: 6-min walking distance; % pred: % predicted; PA–a,O2: alveolar–arterial oxygen tension difference; FVC: forced vital capacity; DL,CO: diffusing capacity of the lung for carbon monoxide; CPI: composite physiologic index; HRCT: high-resolution computed tomography; BAL: bronchoalveolar lavage; ns: not significant; NA: not available. #: a prospective cohort at the Pulmonary Unit, University of Rome “Tor Vergata”, Rome, Italy and a retrospective cohort at the pulmonary unit, University of Siena, Siena, Italy; : n=64; +: n=65; §: mean of the scores from each of the three core radiologists; ƒ: n=28. p-value: Chi-squared, unpaired t-test or Mann–Whitney U-test, where required.