Table 2.
Risk factors for the occurence of acute exacerbation
| Parameters | Hazard ratio (95% CI) | p value | |
| Univariate Cox analysis | |||
| Males, sex | 0.98 | (0.43-2.24) | NS |
| Age (yrs) | 1.02 | (0.97-1.07) | NS |
| BMI (kg/m^2) | 1.03 | (0.94-1.12) | NS |
| Smoking history | 1.01 | (0.46-2.20) | NS |
| Family history | 1.86 | (0.85-4.08) | NS |
| BAL | |||
| Total cell count (×10^5) | 1.13 | (0.89-1.43) | NS |
| Macrophages (%) | 1.01 | (0.98-1.03) | NS |
| Lymphocytes (%) | 0.99 | (0.97-1.02) | NS |
| Neutrophils (%) | 1.03 | (0.97-1.10) | NS |
| Eosinophils (%) | 1.02 | (0.84-1.24) | NS |
| 6-minute walk test (6MWT) | |||
| Distance (meter) | 0.99 | (0.988-0.99) | 0.02 |
| Minimum SpO2, 88% or less | 0.86 | (0.80-0.93) | <0.001 |
| ΔSpO2, 4% or more | 1.63 | (0.74-3.55) | NS |
| KL-6 (U/mL) | 1.001 | (1.001-1.005) | 0.002 |
| SP-D (ng/mL) | 1.003 | (1.001-1.005) | 0.003 |
| LDH (U/L) | 1.01 | (0.998-1.01) | NS |
| CRP (mg/dL) | 1.20 | (1.06-1.35) | 0.003 |
| PaO2(Torr) | 0.94 | (0.90-0.98) | 0.005 |
| FVC %pred | 0.97 | (0.95-0.99) | 0.007 |
| DLco %pred | 0.99 | (0.99-1.01) | NS |
| 10% or more FVC decline in 1 year | 7.45 | (3.12-17.77) | <0.001 |
| 15% or more DLco decline in 1 year | 2.74 | (1.06-7.10) | 0.038 |
| KL-6 increase in 1 year (U/mL) | 1.21 | (0.54-2.70) | NS |
| SP-D increase in 1 year (ng/mL) | 1.67 | (0.70-3.98) | NS |
| Multivariate Cox analysis | |||
| Minimum SpO2 in 6 MWT, 88% or less | 5.28 | (1.44-19.32) | 0.012 |
| 10% or more FVC decline in 1 year | 4.14 | (1.26-13.65) | 0.020 |
| 15% or more DLco decline in 1 year | 4.66 | (1.19-18.17) | 0.027 |
Cox proportional hazards regression model was used. Definition of abbreviations: BMI: body mass index, BAL: Bronchoalveolar lavage, SpO2: arterial oxygen saturation measured by pulse oximetry, ΔSpO2: difference from the resting SpO2 to the minimum SpO2, KL-6: Krebs von den Lungen-6, SP-D: surfactant protein-D, LDH: lactate dehydrogenase, CRP: C-reactive protein, PaO2: partial pressure of oxygen in arterial blood, FVC: forced vital capacity, %pred: % predicted, DLco diffusion capacity of the lungs for carbon monoxide, NS: not significant.