Risk Factors Associated with Misuse of Soft Mist Inhaler in Patients with Chronic Obstructive Pulmonary Disease

Figures & data

Table 1 Error Rate of Participants for Each Step of Soft Mist Inhaler Use

Step for Soft Mist Inhaler use	Frequency of Errors
Keep cap closed, rotate device base half a turn until a “click” is heard.	28 (17.6)
Cap open until it clicks into open position	27 (17.0)
Hold the device in a correct position	0 (0.0)
Exhale before inhalation	113 (71.1)
Close lips around the mouthpiece end	13 (8.2)
Coordination between actuation and inhalation	43 (27.0)
Inhale deeply and slowly	46 (28.9)
Hold your breath for 5~10 seconds	66 (41.5)
Exhale slowly	25 (15.7)
Close cap	2 (1.3)
Patients performing at least one step incorrectly	136 (85.5)
Patients performing at least one critical step incorrectly	74 (46.5)

Notes: Data are presented as the number (%). Critical errors are shown in bold typeface.

Table 2 Clinical Characteristics of Study Participants

Characteristics	N = 159
Age (years)	70.39 ± 7.31
Male	151 (95.0)
BMI (kg/m^2)	23.33 ± 3.45
Duration of COPD (years)	3.33 ± 4.30
Duration of SMI use (years)	2.59 ± 3.16
Smoking status
Never smoker	17 (10.7)
Ex-smoker	117 (73.6)
Current smoker	25 (15.7)
Severe exacerbation in the prior year	35 (22.0)
Prior education in inhaler technique	151 (95.0)
Adherence
Good	126 (79.2)
Partial or poor	33 (20.8)
Education level
< High school	95 (59.7)
≥ High school	64 (40.3)
Spirometry
Percentage predicted FVC	74.69 ± 15.95
Percentage predicted FEV1	61.56 ± 17.20
FEV1/FVC (%)	57.80 ± 13.82
GOLD stage
1 (FEV1 > 80% predicted)	58 (36.5)
2 (50% ≤ FEV1 < 80% predicted)	79 (49.7)
3 (30% ≤ FEV1 < 50% predicted)	10 (6.3)
4 (FEV1 < 30% predicted)	12 (7.5)
mMRC score	1.31 ± 0.88
< 2	97 (61.0)
≥ 2	62 (39.0)
CAT score	10.08 ± 5.88
< 10	97 (61)
≥ 10	62 (39)

Notes: Data are presented as the mean ± standard deviation or number (percentage).

Abbreviations: BMI, body mass index; SMI, soft mist inhaler; COPD, chronic obstructive pulmonary disease; CAT, COPD assessment test; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; mMRC, modified Medical Research Council.

Table 3 Characteristics of the Participants According to Any Error of SMI Use

Characteristics	Any Error of SMI Use		P value
	No (n=23)	Yes (n=136)
Age (years)	70.26 ± 7.09	70.41 ± 7.37	0.927
BMI (kg/m^2)	23.90 ± 2.93	23.25 ± 3.63	0.449
Duration of COPD (years)	2.70 ± 4.16	3.43 ± 4.32	0.451
≤ 2 years	18 (78.3)	76 (55.9)	0.043
> 2 years	5 (21.7)	60 (44.1)
Duration of SMI use (years)	2.44 ± 3.39	2.62 ± 3.14	0.810
≤ 2 years	19 (82.6)	84 (61.8)	0.053
> 2 years	5 (17.4)	52 (38.2)
Adherence			0.003
Good	23 (100)	103 (75.7)
Partial or poor	0 (0)	33 (28.2)
Education level			0.002
< High school	7 (30.4)	88 (64.7)
≥ High school	16 (69.6)	48 (35.3)
mMRC score	1.13 ± 0.87	1.35 ± 0.88	0.279
< 2	15 (65.2)	82 (60.3)	0.419
≥ 2	8 (34.8)	54 (39.7)
CAT score	7.96 ± 4.03	10.44 ± 6.07	0.016
< 10	19 (82.6)	78 (57.4)	0.022
≥ 10	4 (17.4)	58 (42.6)
GOLD stage			0.412
1 (FEV1 ≥ 80% predicted)	4 (17.4)	13 (9.6)
2 (50% ≤ FEV1 < 80% predicted)	12 (52.2)	85 (62.5)
3 (30% ≤ FEV1 < 50% predicted)	7 (30.4)	32 (23.5)
4 (FEV1 < 30% predicted)	0 (0)	6 (4.4)

Notes: Data are presented as the mean ± standard deviation or number (percentage).

Abbreviations: SMI, soft mist inhaler; BMI, body mass index; COPD, chronic obstructive pulmonary disease; mMRC, modified Medical Research Council; CAT, COPD assessment test; GOLD, global initiative for chronic obstructive lung disease; FEV₁, forced expiratory volume in 1 second.

Table 4 Risk Factors for Any Error of SMI Use by Binary Logistic Regression Analysis

Variable	Adjusted OR (95% CI)	P value
Education		0.023
≥ High school	Reference
< High school	3.258 (1.175–9.034)
CAT score		0.049
< 10	Reference
≥ 10	3.341 (1.008–11.075)
Duration of COPD		0.018
> 2 years	Reference
≤ 2 years	3.819 (1.253–11.637)

Notes: Data are presented as odds ratios and 95% confidence intervals. Model adjusted for age, sex, duration of COPD, duration of SMI use, CAT score, level of education, and inhaler adherence.

Abbreviations: SMI, soft mist inhaler; OR, odds ratio; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease.

Data Sharing Statement

The data that support the findings of this study are available on request from the corresponding author on reasonable request.