Table 3

Subgroup analyses (ATOS responders vs non-responders)—results. Data presented as median (IQR)

Non-responder (n=24)Responder (n=26)P valuex)Median effect (95% CI)
responder—non-responder
Baseline characteristics
FEV1, % predicted29.4 (25.6, 36.9)30.1 (24.1, 33.4)0.67
RV,/TLC, % predicted182.8 (168.0, 203.0)199.3 (178.7, 209.6)0.18
FRC, % predicted207.7 (176.5, 240.3)228.7 (188.5, 252.7)0.42
PO2—rest with room air, mm Hg53.6 (52.0, 57.2)54.7 (50.4, 57.3)0.86
PCO2—rest with room air, mm Hg44.4 (39.5, 46.8)44.6 (38.1, 48.6)0.72
O2 flow rate—exercise, L/min3.5 (3.0, 4.0)3.0 (2.5, 4.0)0.42
Age, years66.5 (61.0, 73.0)62.0 (59.0, 68.0)0.20
BMI, kg/m224.3 (21.3, 26.4)23.7 (21.3, 26.1)0.45
Waist circumference, cm96.5 (89.5, 107.0)89.5 (83.0, 100.5)0.13
Waist–hip ratio0.97 (0.89, 1.0)0.91 (0.86, 0.98)0.14
ESWTATOS
Mean O2-flow rate, L3.9 (2.6, 4.7)5.2 (3.9, 6.7)8.768E–031.6 (0.49 to 2.7)
Time, s280.0 (199.0, 857.0)751.5 (419.0, 1200.0)2.664E–03268 (75 to 549)
Distance, m265.0 (155.0, 925.0)675.0 (350.0, 1210.0)1.287E–02225 (50 to 530)
Blood gas analyses
PO2rest, mm Hg65.4 (62.7, 67.9)65.1 (61.0, 68.6)0.75
PO2post, mm Hg66.3 (60.7, 73.2)74.1 (71.0, 76.6)3.364E–037.25 (2.4 to 11.6)
SaO2rest, mm Hg93.1 (91.4, 93.7)92.9 (91.7, 93.3)0.62
SaO2post, mm Hg91.8 (88.9, 93.7)93.5 (92.0, 94.2)4.141E–021.24 (0.04 to 2.8)
PCO2rest, mm Hg40.8 (39.9, 47.0)41.8 (39.0, 48.3)0.74
PCO2post, mm Hg48.3 (46.2, 53.6)51.6 (48.6, 56.1)0.23
Phrest7.41 (7.39, 7.43)7.41 (7.40, 7.43)0.68
Phpost7.36 (7.33, 7.38)7.34 (7.31, 7.36)0.05
Lactaterest, mmol/L1.2 (1.0, 1.6)1.0 (0.8, 1.2)0.14
Lactatepost, mmol/L1.9 (1.6, 2.4)1.4 (1.0, 2.2)0.08
Borg scale
Dyspnoeapost, points6.0 (4.0, 7.5)5.0 (4.0, 5.0)1.107E–02–1 (–2 to 0)
ΔDyspnoea, points4.0 (3.0, 6.5)3.0 (2.0, 4.0)1.614E–03–1 (–2 to 0)
Leg fatiguepost, points6.0 (4.0, 7.5)4.0 (3.0, 5.0)0.35
ΔLeg fatigue, points4.0 (3.0, 6.5)2.0 (1.0, 3.0)0.58
  • Differences with p values<0.01 are presented in bold. Note: Median effects are not necessarily medians of differences; x)Mann-Whitney U test. P values are unadjusted for multiple comparisons.

  • ATOS, automatically titrating oxygen system; BMI, body mass index; ESWT, endurance shuttle walk test; FEV1, forced expiratory volume in 1 s; FRC, functional residual capacity; PCO2, partial pressure of carbon dioxide; pH, potential of hydrogen; PO2, partial pressure of oxygen; RV, residual volume; SaO2, oxygen saturation measured by blood gas analyses; TLC, total lung capacity.