AE | SAE | p-value | All | |

Patients n | 11 | 7 | 18 | |

Baseline characteristics | ||||

Males | 9 (81.8) | 7 (100) | 0.49 | 16 (88.9) |

Caucasians | 10 (90.9) | 7 (100) | 1 | 17 (94.4) |

Current or ex-smoker | 5 (45.4) | 4 (57.1) | 1 | 9 (50) |

Room air P_{a,O2} mmHg | 75 (68–84) | 74^{#} | 74.5 (68–84) | |

FVC % pred | 75 (70–78) | 66 (57–78) | 0.54 | 70 (62–78) |

D_{L,CO} % pred | 40.5 (36–46.5) | 46 (38–49) | 0.57 | 42 (38–47) |

6MWD m | 415 (350–420) | 422.5 (380–457.5) | 0.37 | 415 (350–425) |

Characteristics at time of exacerbation | ||||

Age yrs | 67 (65–72) | 67 (58–73) | 0.93 | 67 (65–72) |

BMI kg·m^{−2} | 28.8 (27.7–31.7) | 26.4 (24.2–29) | 0.22 | 27.9 (25.6–30.6) |

Time from onset of symptoms to admission days | 7 (3–18) | 47 (39–62) | 0.003 | 18.5 (6–44) |

Proportion of new opacities on HRCT that were multifocal or diffuse | 6/9 (66.7) | 2/5 (40) | 0.58 | 8/14 (57.1) |

Room air P_{a,O2} mmHg | 53.5 (47–59.5) | 60 (54–66) | 0.33 | 55 (51–68) |

P_{a,O2}/F_{I,O2} | 255 (224–283) | 286 (257–314) | 0.33 | 262 (243–324) |

FVC % pred | 57 (51–61) | 56 (50–65) | 0.81 | 57 (50–64) |

D_{L,CO} % pred | 25 (19–34) | 24 (22–37) | 0.90 | 24 (22–34) |

Data are expressed as median (interquartile range) for continuous variables and n (%) or n/N (%) for categorical variables, unless otherwise stated. Data and groups were compared using Fisher's exact test and Mann–Whitney U-test. In all cases, two-sided tests were used; p-values <0.05 (shown in bold text) were deemed statistically significant. AE: acute exacerbation; SAE: sub-acute exacerbation;

*P*_{a,O2}: arterial oxygen tension; FVC: forced vital capacity; % pred: % predicted;*D*_{L,CO}: diffusion capacity of the lung for carbon monoxide; 6MWD: 6-min walking test distance; BMI: body mass index; HRCT: high-resolution computed tomography*F*_{I,O2}: inspired oxygen fraction.^{#}: n=1.