Table 3

Variables significantly and not significantly associated with survival by univariate Cox regression analysis

Evaluated parameter Hazard ratio 95% CI p value
Variables significantly associated with survival
Age (years)1.0371.002 to 1.0720.04
Pulmonary function
 FEV1(l)0.4670.254 to 0.8590.01
 FVC (l)0.5530.349 to 0.8760.01
 TLC (l)0.6820.497 to 0.9350.02
 TLC (% predicted)0.9800.962 to 0.9970.03
 Tlco (mmol/kPa/min)0.6300.480 to 0.8260.0008
 Tlco (% predicted)0.9560.933 to 0.9790.0003
Blood gas analysis
 Pao 2 (kPa)0.6610.532 to 0.8210.0002
 Sao 2(%)0.8950.847 to 0.9450.0001
HRCT score
 HRCT fibrosis score1.8621.054 to 3.2900.03
DTPA clearance
 T 0.5 F(min)0.7950.633 to 0.9970.04
Variables not significantly associated with survival
Male sex0.7780.402 to 1.5090.458
Never smoking1.0760.545 to 2.1190.832
Pulmonary function
 FEV1 (% predicted)0.9880.971 to 1.0050.166
 FVC (% predicted)0.9870.971 to 1.0020.091
 Kco(mmol/kPa/min/l)0.4660.173 to 1.2510.130
 Kco (% predicted)0.9930.978 to 1.0080.336
Blood gas analysis
 Paco 2(kPa)0.7680.442 to 1.3370.351
BAL differential cell counts
 Macrophages (%)1.0100.991 to 1.0300.312
 Neutrophils (%)1.0020.982 to 1.0220.865
 Lymphocytes (%)1.0020.963 to 1.0420.938
 Eosinophils (%)0.9670.918 to 1.0190.210
HRCT score
 HRCT ground glass score0.8600.637 to 1.1610.324
DTPA clearance variables
 t 0.5(min)0.9830.950 to 1.0170.32
 t 0.5 S(min)1.0090.987 to 1.0300.44
 f F (%)1.0090.992 to 1.0270.30

  • FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity; TLC = total lung capacity; Tlco = carbon monoxide transfer factor; Kco= carbon monoxide transfer coefficient; Pao 2 = arterial oxygen tension; Paco 2 = arterial carbon dioxide tension; Sao 2 = oxygen saturation; HRCT = high resolution CT;t 0.5 F= half time for the fast component of the bi-exponential DTPA clearance curve; t 0.5 = half time for mono-exponential approximation to the early part of the DTPA clearance curve;t 0.5 S= half time for the fast component of the bi-exponential DTPA clearance curve; f F = fraction of tracer cleared by the fast component.