Comparative Study of Inhaler Device Handling Technique and Risk Factors for Critical Inhaler Errors in Korean COPD Patients

Figures & data

Table 1 Baseline Characteristics of the COPD Patients According to Correct or Erroneous Inhaler Usage

Variable	Total (n=261)	Correct Usage (n=139)	Any Critical Error (n=122)	P-value
Age (years)	69.8 ± 7.7	69.6 ± 7.2	69.9 ± 8.2	0.729
Male, n (%)	244 (93.5)	137 (98.6)	107 (87.7)	<0.001
Body mass index (kg/m^2)	23.5 ± 3.5	23.9 ± 3.4	23.1 ± 3.5	0.050
Puff burden	2.2 ± 1.3	1.9 ± 0.9	2.6 ± 1.5	<0.001
Adherence				0.008
Good	213 (81.6)	122 (87.8)	91 (74.6)
Partial	42 (16.1)	15 (10.8)	27 (22.3)
Poor	6 (2.3)	2 (1.4)	4 (3.3)
COPD duration (years)	3.6 ± 4.3	3.7 ± 4.5	3.4 ± 4.2	0.631
Previous education on COPD	249 (95.4)	133 (95.7)	116 (95.1)	0.817
Previous education on inhaler use	249 (95.4)	135 (97.1)	114 (93.4)	0.157
Educational level				0.026
Low (≤ 6 years)	99 (37.9)	44 (31.7)	55 (45.1)
High (> 6 years)	162 (62.1)	95 (68.3)	67 (54.9)
FEV1/FVC (%)	58.6 ± 13.7	59.4 ± 12.7	57.7 ± 14.8	0.344
Percentage predicted FEV1	63.5 ± 17.5	64.4 ± 15.4	62.4 ± 19.6	0.373
Percentage predicted DLCO (n=258)	68.4 ± 19.5	70.9 ± 20.5	65.5 ± 18.0	0.027
GOLD stage				0.012
I, II	204 (78.1)	117 (84.2)	87 (71.3)
III, IV	57 (21.9)	22 (15.8)	35 (28.7)
mMRC score	1.3 ± 0.9	1.1 ± 0.8	1.5 ± 0.9	0.001
CAT score	9.9 ± 5.6	9.1 ± 4.7	10.8 ± 6.3	0.018
MMSE score (n=258)	29.3 ± 1.6	29.6 ± 1.1	29.2 ± 2.0	0.030
FSI-10 score	44.4 ± 4.7	45.2 ± 4.3	43.4 ± 4.9	0.001
PHQ-9 score	1.1 ± 2.3	1.3 ± 2.6	1.0 ± 1.9	0.298
EQ-5D score	0.9 ± 0.1	0.9 ± 0.1	0.8 ± 0.1	0.028
Frequent exacerbations in the prior year	65 (24.9)	26 (18.7)	39 (32.0)	0.013

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

Abbreviations: CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; DLCO, diffusion capacity for carbon monoxide; EQ-5D, EuroQol-5D; FEV₁, forced expiratory volume in 1 second; FSI-10, Feeling of Satisfaction with Inhaler questionnaire; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; mMRC, modified Medical Research Council; MMSE, Mini-Mental State Examination; PHQ-9, patient health questionnaire.

Figure 1 Percentages of any overall error and any critical error for each inhaler type.

Table 2 Factors Associated with Any Critical Error for Each Inhaler Type

	DPI (n=143)			SMI (n=145)			pMDI (n=20)
	Correct Usage (n=87)	Any Critical Error (n=56)	P-value	Correct Usage (n=79)	Any Critical Error (n=66)	P-value	Correct Usage (n=9)	Any Critical Error (n=11)	P-value
Age (years)	68.6 ± 7.8	68.9 ± 8.2	0.805	70.1 ± 6.7	71.0 ± 8.1	0.474	67.8 ± 6.1	70.4 ± 9.2	0.479
Male, n (%)	86 (98.9)	48 (85.7)	0.002	77 (97.5)	60 (90.9)	0.142	9 (100)	10 (90.9)	1.000
Body mass index (kg/m^2)	23.8 ± 3.4	23.4 ± 3.5	0.492	23.8 ± 3.7	22.8 ± 3.3	0.093	25.2 ± 2.8	24.5 ± 4.8	0.685
Puff burden	2.3 ± 1.6	2.6 ± 1.7	0.286	2.4 ± 1.0	2.5 ± 1.2	0.533	1.4 ± 0.5	1.7 ± 0.5	0.220
COPD duration (years)	4.4 ± 4.4	3.1 ± 3.1	0.066	3.1 ± 4.0	3.7 ± 4.8	0.413	4.1 ± 4.8	3.7 ± 4.8	0.857
Inhaler usage duration	3.5 ± 3.4	2.8 ± 2.6	0.170	2.6 ± 2.9	2.6 ± 3.4	0.956	4.0 ± 4.8	3.7 ± 4.8	0.873
Previous education on inhaler	82 (94.3%)	52 (92.9%)	0.737	76 (96.2%)	61 (92.4%)	0.469	9 (100%)	10 (90.9%)	1.000
Previous education on COPD	81 (93.1)	54 (96.4)	0.482	75 (94.9)	62 (93.9)	1.000	9 (100)	10 (90.9)	1.000
Educational level			0.659			0.017			0.406
Low (≤6 years)	31 (35.6)	22 (39.3)		22 (27.8)	31 (47.0)		3 (33.3)	6 (54.5)
High (> 6 years)	56 (64.4)	34 (60.7)		57 (72.2)	35 (53.0)		6 (66.7)	5 (45.5)
Percentage predicted FEV1	61.9 ± 17.4	63.5 ± 20.2	0.628	62.6 ± 15.7	60.5 ± 19.3	0.476	57.4 ± 22.1	57.4 ± 18.3	0.993
Percentage predicted DLCO	70.4 ± 19.0	67.1 ± 19.7	0.326	56.0 ± 13.0	56.0 ± 13.0	0.065	68.7 ± 16.0	59.7 ± 20.5	0.299
GOLD stage			0.498			0.160			1.000
I, II	68 (78.2)	41 (73.2)		62 (78.5)	45 (68.2)		6 (66.7)	7 (63.6)
III,IV	19 (21.8)	15 (26.8)		17 (21.5)	21 (31.8)		3 (33.3)	4 (36.4)
mMRC score	1.2 ± 0.8	1.5 ± 0.8	0.042	1.2 ± 0.9	1.4 ± 0.9	0.130	1.2 ± 0.8	2.1 ± 1.0	0.058
CAT score	9.5 ± 4.9	10.7 ± 5.8	0.201	9.3 ± 5.2	10.9 ± 6.3	0.095	8.2 ± 4.6	14.7 ± 6.7	0.024
MMSE score	29.5 ± 1.3	29.1 ± 2.1	0.180	29.7 ± 0.98	29.2 ± 1.9	0.130	29.6 ± 1.3	28.2 ± 3.0	0.224
FSI-10 score	45.4 ± 4.3	42.4 ± 5.5	<0.001	44.7 ± 4.3	43.9 ± 4.6	0.322	42.9 ± 4.0	42.9 ± 3.8	0.991
PHQ-9 score	1.5 ± 3.0	0.9 ± 1.5	0.137	0.9 ± 1.6	1.1 ± 2.2	0.715	0.8 ± 1.4	1.4 ± 2.0	0.462
EQ-5D score	0.9 ± 0.1	0.9 ± 0.1	0.341	0.89 ± 0.07	0.86 ± 0.10	0.020	0.9 ± 0.1	0.7 ± 0.3	0.160
Moderate AEs in the prior year	37 (42.5)	34 (60.7)	0.034	28 (35.4)	27 (40.9)	0.499	4 (44.4)	2 (18.2)	0.336
Severe AEs in the prior year	13 (14.9)	8 (14.3)	0.914	14 (17.7)	19 (28.8)	0.113	1 (11.1)	3 (27.3)	0.591
Frequent AEs in the prior year	21 (24.1)	22 (39.3)	0.054	11 (13.9)	21 (31.8)	0.010	3 (33.3)	1 (9.1)	0.285

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

Abbreviations: AE, acute exacerbation; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; DLCO, diffusion capacity for carbon monoxide; DPI, dry powder inhaler; EQ-5D, EuroQol-5D; FEV₁, forced expiratory volume in 1 second; FSI-10, Feeling of Satisfaction with Inhaler questionnaire; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; mMRC, modified Medical Research Council; MMSE, Mini-Mental State Examination; PHQ-9, patient health questionnaire; pMDI, pressurized metered dose inhaler; SMI, soft mist inhaler.

Table 3 Logistic Regression Model for Any Critical Inhaler Error as a Function of Inhaler Type

	DPI	SMI	pMDI
Sex
Male	1
Female	30.35 (3.20–288.0)
COPD duration	0.86 (0.75–0.98)
Educational level
Low (≤6 years)		2.23 (1.10–4.74)
High (>6 years)		1
CAT score			1.21 (1.01–1.45)
FSI-10 score	0.85 (0.78–0.93)
Moderate AEs in the prior year
Yes	2.56 (1.14–5.72)
No	1
Frequent AEs in the prior year
Yes		2.57 (1.09–6.07)
No		1

Note: Data are presented as odds ratios and 95% confidence intervals.

Abbreviations: AE, acute exacerbation; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; DPI, dry powder inhaler; FSI-10, Feeling of Satisfaction with Inhaler questionnaire; pMDI, pressurized metered dose inhaler; SMI, soft mist inhaler.