Table 1– Characteristics of the unclassifiable ILD and control patients in the study
VariableUnclassifiable ILDIPF controlsp-valueNon-IPF controlsp-value
Patients n132244294
Age years67.8±12.969.7±8.80.0959.6±11.9<0.0005
Sex male53.072.8<0.000532.3<0.0005
Smoking history
 Ever smoked63.675.80.0146.10.001
 Pack-years16.0±23.923.3±25.2<0.00058.5±14.90.001
Measures of disease severity
 Long-term oxygen therapy21.924.70.5416.80.26
 Pulmonary function#
  FVC % predicted69.0±22.169.1±17.80.9768.7±20.30.89
  DLCO % predicted47.6±19.744.0±16.40.0848.5±20.20.66
  • Data are presented as mean±sd or %, unless otherwise stated. ILD: interstitial lung disease; IPF: IPF, idiopathic pulmonary fibrosis; FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide; #: n = 129 for unclassifiable patients. The p-values are reported for comparison between unclassifiable ILD and each ILD subtype using Chi-squared test (sex, smoking history and oxygen therapy), t-test (age, FVC, DLCO), or Wilcoxon rank sum test (pack-years).