Table 1

Baseline characteristics and index admission data

n2012–13 cohort*
n=101
2017–18 cohort†
n=80
P value
Baseline characteristics
Age (years)18178 (68–83)78 (70–84)0.472
Male, n (%)18127 (27)25 (31)0.573
BMI (kg/m2)13323 (19–27)25 (21–29)0.055
FEV1 % of predicted15333 (26–43)38 (24–52)0.246
MRC score1244 (3–5)4 (3–5)0.984
LTOT, n (%)18119 (18.8)14 (17.5)0.837
Smoker, n (%)179
Never8 (7.9)1 (1.2)0.0460
Previous50 (49.5)51 (63.8)0.198
Current42 (41.6)27 (33.8)0.403
Pack-years16440 (30–50)50 (40–60)0.033
COPD admission prior to enrolment, n (%)181
Within 1 month21 (20.8)12 (15.0)0.365
Within1 year40 (39.6)27 (33.8)0.520
Index admission data
Duration of admission (days)1816 (3–9)6 (4–8)0.928
Fever (>38°C), n (%)1799 (8.9)13 (16.2)0.158
Maximum CRP17955 (19–135)32 (14–117)0.124
Antibiotics (oral or intravenous), n (%)18090 (90)67 (84)0.655
RR at NIV initiation15428 (24–32)24 (20–28)0.001
Arterial gasses at NIV initiation
pH1817.28 (7.23–7.31)7.29 (7.25–7.32)0.552
PaCO2 (kPa)1818.8 (7.7–11.0)8.9 (7.8–9.9)0.638
PaO2 (kPa)1769.5 (7.9–11.0)9.2 (8.3–10.4)0.638
HCO3− (mmol/L)17426.0 (23.0–31.0)26.2 (23.2–28.8)0.472
Base excess (mmol/L)1754.0 (−0.2 to 9.7)4.0 (0.2–7.6)0.596
Lactate (mmol/L)1701.1 (0.7–1.9)1.2 (0.8–2.1)0.395
Late-onset acidaemia (>12 hours after admission), n (%)1812 (2)15 (18,8)<0.001
Hyperoxia (Pa02 >16 kPa) on admission, n (%)1806 (6)4 (4,9)0.776
Max IPAP (cm H2O)18012 (10–14)20(18-24)<0.001
Max EPAP (cm H2O1805 (5–5)5 (5–5)0.119
Initially treated in ICU, n (%)1814 (4.0)3 (3.8)0.943
DNI/DNR-order, n (%)17961 (60)33 (42)0.098
Late, >2 hours of admission (% of all DNI/DNR orders)14 (23)9 (27)
NIV failure, n (%)1818 (8.0)2 (2.5)0.123
  • Data is presented as median (IQR) unless stated otherwise. Comparison of groups using Mann-Whitney U test or χ2 test.

  • *Low IPAP regime.

  • †High IPAP regime.

  • BMI, body mass index; COPD, chronic obstructive pulmonary disease; CRP, C reactive protein; DNI/DNR, do not intubate/do not resuscitate; EPAP, expiratory positive airway pressure ; FEV1, forced expiratory volume in 1 s; ICU, intensive care unit; IPAP, inspiratory positive airway pressure; LTOT, long-term oxygen treatment; MRC, Medical Research Council Dyspnoea Scale; NIV, non-invasive ventilation; RF, respiratory frequency.