Daily home-based spirometry during withdrawal of inhaled corticosteroid in severe to very severe chronic obstructive pulmonary disease

Figures & data

Table 1 Baseline demographic and clinical characteristics of patients providing data for at least one visit for both in-clinic trough FEV₁ and corresponding home-based weekly mean FEV₁ (treated set)

	ICS (n=1,080)	ICS withdrawal (n=1,081)	Total (n=2,161)
Sex, n (%)
Male	869 (80.5)	891 (82.4)	1,760 (81.4)
Female	211 (19.5)	190 (17.6)	401 (18.6)
Mean (SD) age, years	63.4 (8.6)	63.8 (8.3)	63.6 (8.4)
Race, n (%)
Native American/Alaska native	0 (0.0)	1 (0.1)	1 (<0.1)
Asian	125 (11.6)	136 (12.6)	261 (12.1)
Black/African-American	6 (0.6)	3 (0.3)	9 (0.4)
Hawaiian/Pacific Islander	4 (0.4)	3 (0.3)	7 (0.3)
White	884 (81.9)	878 (81.2)	1,762 (81.5)
Missing	61 (5.6)	60 (5.6)	121 (5.6)
Mean (SD) body mass index, kg/m^2	25.3 (5.1)	25.2 (5.0)	25.2 (5.1)
Mean (SD) COPD duration, years	7.7 (6.0)	8.1 (6.6)	7.9 (6.3)
Smoking status, n (%)
Ex-smoker	702 (65.0)	734 (67.9)	1,463 (66.5)
Current smoker	378 (35.0)	347 (32.1)	725 (33.5)
Mean (SD) smoking history, pack-years	43.8 (23.4)	45.0 (24.6)	44.4 (24.0)
GOLD postbronchodilator,a n (%)
1	1 (0.1)	1 (0.1)	2 (0.1)
2	5 (0.5)	2 (0.2)	7 (0.3)
3	670 (62.0)	674 (62.3)	1,344 (62.2)
4	401 (37.1)	404 (37.4)	805 (37.3)
Missing	3 (0.3)	0 (0.0)	3 (0.1)
Mean (SD) baseline lung functionb
FEV1, L	0.97 (0.36)	0.99 (0.36)	0.98 (0.36)
FEV1 % predicted	34.3 (10.9)	34.6 (10.6)	34.46 (10.8)
FVC, L	2.43 (0.72)	2.50 (0.73)	2.47 (0.73)
FEV1/FVC, %	43.1 (11.6)	42.6 (11.7)	42.8 (11.7)
PEFR, L/s	3.30 (1.21)	3.35 (1.20)	3.32 (1.21)

Notes:

a At screening;

b prebronchodilator dose; ICS, n=1,076; ICS withdrawal, n=1,076; total, n=2,152.

Abbreviations: COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, Global initiative for chronic Obstructive Lung Disease; ICS, inhaled corticosteroid; PEFR, peak expiratory flow rate; SD, standard deviation.

Figure 1 Adjusted mean (SE) changes from baseline in weekly mean^a FEV₁ values derived from home-based spirometric data.

Notes: ^aMean of the daily home-based FEV₁ values recorded in the week prior to the clinic visit, calculated if ≥4 of the 7 days had non-missing measurements. **P<0.001; ***P≤0.0001 vs ICS; restricted maximum-likelihood repeated measures model; baseline values 970 mL for ICS, 981 mL for ICS withdrawal. Total number of patients included in the analysis with baseline and ≥4 measurements in the week prior to ≥1 of the clinic visits was 2,237 (1,118 in the ICS group and 1,119 in the ICS-withdrawal group).
Abbreviations: FEV₁, forced expiratory volume in 1 second; ICS, inhaled corticosteroid; SE, standard error.

Table 2 Change from baseline in home-based measurements of on-treatment weekly mean FVC

	Treatment	Adjusted mean, L	Comparison vs ICS
			Adjusted mean difference, L	95% CI
Study week 6	ICS	−0.12
	ICS withdrawal	−0.09	0.03	−0.02, 0.08
Study week 12	ICS	−0.11
	ICS withdrawal	−0.11	0.01	−0.04, 0.05
Study week 18	ICS	−0.12
	ICS withdrawal	−0.12	0.00	−0.05, 0.05
Study week 27	ICS	−0.12
	ICS withdrawal	−0.15	−0.02	−0.07, 0.02
Study week 36	ICS	−0.14
	ICS withdrawal	−0.16	−0.02	−0.07, 0.03
Study week 45	ICS	−0.14
	ICS withdrawal	−0.17	−0.03	−0.08, 0.02
Study week 52	ICS	−0.16
	ICS withdrawal	−0.20	−0.04	−0.09, 0.01

Note: P>0.05 for all treatment differences (not significant).

Abbreviations: CI, confidence interval; FVC, forced vital capacity; ICS, inhaled corticosteroid.

Table 3 Change from baseline in home-based measurements of on-treatment PEFR

	Treatment	Adjusted mean, L/s	Comparison vs ICS
			Adjusted mean difference, L/s	95% CI
Study week 6	ICS	−0.23
	ICS withdrawal	−0.23	−0.00	0.07, 0.07
Study week 12	ICS	−0.27
	ICS withdrawal	−0.29	−0.02	−0.09, 0.05
Study week 18	ICS	−0.30
	ICS withdrawal	−0.44	−0.14**	−0.21, −0.07
Study week 27	ICS	−0.32
	ICS withdrawal	−0.43	−0.11*	−0.19, −0.04
Study week 36	ICS	−0.35
	ICS withdrawal	−0.47	−0.12*	−0.20, −0.04
Study week 45	ICS	−0.37
	ICS withdrawal	−0.49	−0.12*	−0.20, −0.04
Study week 52	ICS	−0.38
	ICS withdrawal	−0.54	−0.16**	−0.25, −0.07

Notes:

* P<0.01;

** P<0.001.

Abbreviations: CI, confidence interval; ICS, inhaled corticosteroid; PEFR, peak expiratory flow rate.

Figure 2 Bland–Altman analysis demonstrating the agreement between in-clinic and home-based spirometry results across all visits.

Abbreviations: FEV₁, forced expiratory volume in 1 second; SD, standard deviation.

Figure 3 Bland–Altman analysis demonstrating the agreement between in-clinic and home-based spirometry results at weeks 6, 12, 18, and 52.

Abbreviations: FEV₁, forced expiratory volume in 1 second; SD, standard deviation.