Efficacy and safety of long-term use of a positive expiratory pressure device in chronic obstructive pulmonary disease patients, a randomized controlled trial

Table 3 Secondary outcomes

	Intervention group		P	Control group		P	Intervention group D (T0-T1)	Control group D (T0-T1)	P
	T0	T1	P	T0	T1		Intervention group D (T0-T1)	Control group D (T0-T1)	P
Initial S_pO₂, %	96 ± 2	96 ± 2	0.137	96 ± 1	95 ± 1	0.032	− 0.38 ± 0.87	0.75 ± 0.90	0.007
Minimal S_pO₂, %	93 ± 2	93 ± 2	0.025	93 ± 2	92 ± 1	0.01	− 0.62 ± 0.87	0.83 ± 0.94	0.001
End S_pO₂, %	95 ± 3	95 ± 2	0.861	95 ± 1	94 ± 1	0.005	− 0.08 ± 1.55	0.92 ± 0.90	0.065
IC, % predicted	90 ± 22	94 ± 22	0.239	96 ± 26	93 ± 24	0.472	− 4.69 ± 13.64	2.85 ± 13.26	0.175
FVC, % predicted	102 ± 13	103 ± 16	0.522	96 ± 28	98 ± 29	0.483	− 1.76 ± 9.65	− 1.55 ± 7.40	0.952
FEV1, % predicted	85 ± 22	91 ± 19	0.173	77 ± 29	74 ± 30	0.129	− 6.46 ± 16.08	2.86 ± 6.03	0.072
FEV1/ FVC, %	65 ± 14	70 ± 12	0.145	62 ± 13	59 ± 13	0.006	− 4.09 ± 9.45	2.92 ± 2.96	0.022
MVV, % predicted	91 ± 26	102 ± 25	0.024	81 ± 31	81 ± 34	0.935	− 10.65 ± 14.86	0.30 ± 12.38	0.058
mMRC score	1 (1, 1)	0 (0, 0.5)	0.002	0.5 (0, 1.75)	0 (0, 1)	0.157	1 (0.5, 1)	0 (0, 0)	0.003

Definition of abbreviations: Initial S_pO₂ = oxygen saturation at the beginning of the 6-min walking test; Minimal S_pO₂ = minimal oxygen saturation during the 6-min walking test; End S_pO₂ = oxygen saturation at the end of the 6-min walking test; IC = inspiratory capacity; FVC = forced vital capacity; FEV₁ = forced expiratory volume in one second; MVV = maximum voluntary ventilation; mMRC score = modified Medical Research Council dyspnea score. Data are shown as mean ± SD or median ([Q1, Q3]). T0 refers to the time when subjects were enrolled. T1 refers to the time when subjects were followed up at 2 months after enrollment. D (Difference) refers to the value at T0 minus the value at T1 (D = T0 minus T1). In order to determine the statistical significance, we used independent sample t test, Mann–Whitney U test, paired t-test or Wilcoxon test

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