Prevalence and Associated Factors of Suboptimal Daily Peak Inspiratory Flow and Technique Misuse of Dry Powder Inhalers in Outpatients with Stable Chronic Airway Diseases

Figures & data

Figure 1 The research flow chart.

Table 1 Checklist for the Technical Assessment of HAN/TUR/DIS Inhaler Use

The steps of HAN

Open the dust cap by pulling it upwards, then open the mouthpiece. Place the capsule in the center chamber. Close the mouthpiece firmly until hearing a click, leaving the dust cap open. Keep the mouthpiece upwards, then press the piercing button completely in 1 time and release. Breathe out completely, do not exhale into the mouthpiece*. Close your lips tightly around the mouthpiece, breathe in rapidly and steadily, as deeply as possible, and you should hear the capsule rattle*^#. Hold your breath*. Breathe normally after holding breath*. To ensure you get the full dose, repeat the inhalation from the HAN as described. After the dose, open the mouthpiece, tip out the used capsule, and throw it away. Close the mouthpiece and dust cap for storage. Clean the device once a month and let it dry completely before use.

The steps of TUR

Twist and remove the cover. Hold the inhaler upright with the mouthpiece facing up. Turn the grip right and left until it clicks. Breathe out completely, do not exhale into the mouthpiece*. Breathe in rapidly and steadily, as deeply as possible*^#. Hold breath*. Breathe normally after holding breath*. Close the cover. If a second dose is needed, separate the two doses for 30 seconds, and repeat the operation as above. Gargle after inhaling ICS-containing drugs. Know how to judge the remaining dose. Keep the medicine in a dry place.

The steps of DIS

Hold the inhaler in one hand and face the metering window, and place the thumb of the other hand on the inhaler thumb handle and push it. Pull down the slide bar with the thumb, then will hear a “click”. Breathe out completely, do not exhale into the mouthpiece*. Breathe in rapidly and steadily, as deeply as possible*^#. Hold breath*. Breathe normally after holding breath*. Close the cover (no need to return the slide bar). If a second dose is needed, separate the two doses for 30 seconds, and repeat the operation as above. Gargle after inhaling ICS-containing drugs. Know how to judge the remaining dose. Keep the medicine in a dry place.

Notes: *These steps were the breathing-related steps. ^#Instead of using observation evaluation, but use peak flow rate evaluation by In-Check Dial.

Abbreviations: HAN, HandiHaler^®; TUR, Turbuhaler^®; DIS, Diskus^®.

Table 2 Demographical Characteristics and Clinical Data of the Patients

Variables	Total (n=85)	COPD (n=52)	Asthma (n=22)	ACO (n=11)
Demographics
Age (y)	67.0 [60.5; 74.0]	68.0 [65.0; 75.8]	58.0 [45.0; 71.0]	63.0 [60.0; 67.0]
Gender(%male)	68 (80.0)	49 (94.2)	8 (36.4)	11 (100.0)
Weight (kg)	66.5 [55.0; 70.0]	65.0 [55.0; 70.0]	67.0 [60.0; 73.0]	72.5 [60.0; 78.0]
Smoking (%)	65 (76.5)	49 (94.2)	2 (9.1)	10 (90.9)
Smoking Index	600.0 [2.0; 1000.0]	800.0 [510.0;1200.0]	[0.0;0.0]	600.0 [300.0; 800.0]
With respiratory diseases (%combined)	9 (10.6)	7 (13.5)	1 (4.5)	1 (9.1)
Education Level   Illiteracy	1 (1.2)	1 (1.9)	0 (0.0)	0 (0.0)
Primary school	16 (18.8)	10 (19.2)	5 (22.7)	1 (9.1)
Junior high school	30 (35.3)	22 (42.3)	5 (22.7)	3 (27.3)
High school	13 (15.3)	8 (15.4)	2 (9.1)	3 (27.3)
University and above	21 (24.7)	10 (19.2)	8 (36.4)	3 (27.3)
Missing value	4 (4.7)	1 (1.9)	2 (9.1)	1 (9.1)
FEV1%Predicted	59.5 [33.1, 77.8]	57.6 [31.7, 72.9]	86.5 [67.9, 92.7]	45.4 [33.0, 52.2]
CAT		13.0 ± 7.4		14.0 ± 5.1
mMRC scale
0		8 (15.4)		0 (0.0)
1		12 (23.1)		5 (45.5)
2		16 (30.8)		4 (36.4)
3		9 (17.3)		2 (18.2)
4		7 (13.5)		0 (0.0)
ACT			21.0[19.0; 22.0]
Received medication education before
Yes	85 (100)	52 (100)	22 (100)	11 (100)
Inhalation Type (after randomization^#)
Number of people using HAN	29 (34.1)	18 (34.6)	7 (31.8)	4 (36.4)
Number of people using TUR	29 (34.1)	19 (35.8)	10 (47.6)	0 (0.0)
Number of people using DIS	27 (31.8)	15 (28.3)	5 (23.8)	7 (63.6)

Notes: Data are presented as mean ± SD or numbers (percentages), median [Lower quartile, Upper quartile]; ^#If a patient uses a DPI, the patient is included in the corresponding device group; If patients use two different DPIs, they will be randomly assigned to one of the device groups.

Abbreviations: ACO, asthma-COPD Overlap; BMI, body mass index; COPD, Chronic obstructive pulmonary disease; DPI, dry powder inhaler; HAN, HandiHaler^®; TUR, Turbuhaler^®; DIS, Diskus^®.

Figure 2 The daily PIFs distribution of DPIs.

Notes: Kruskal-Wallis test showed a significant difference in the distribution of the Daily PIFs among the three devices (P<0.001), and further paired comparisons found a significant difference between HAN and TUR (P <0.001), and HAN and DIS (P <0.001).

Abbreviations: DPI, dry powder inhaler; HAN, HandiHaler^®; TUR, Turbuhaler^®; DIS, Diskus^®.

Table 3 The Distribution of the Number of Patients’ Technique Error with Different DPIs

	DPIs			P -value
	HAN (n=29)	TUR(n=29)	DIS (n=27)
The number of technique errors
0	8 (27.6)	9 (31.0)	12 (44.4)	0.164
1	9 (31.0)	4 (13.8)	5 (18.5)
2	10 (34.5)	7 (24.1)	8 (29.6)
3	2 (6.9)	5 (17.2)	2 (7.4)
4	0 (0.0)	4 (13.8)	0 (0.0)
The number of breathing-related steps errors
0	8 (27.6)	11 (37.9)	13 (48.1)	0.244
1	11 (37.9)	12 (41.4)	8 (29.6)
2	9 (31.0)	6 (20.7)	6 (22.2)
3	1 (3.4)	0 (0.0)	0 (0.0)
The number of non-breathing-related steps errors
0	26(89.7)	13 (44.8)	21 (77.8)	<0.001*
1	3 (10.3)	8 (27.6)	5 (18.5)
2	0 (0.0)	7 (24.1)	1 (3.7)
3	0 (0.0)	1 (3.4)	0 (0.0)

Notes: Data are presented as numbers (percentages); Performed by Kruskal–Wallis test; *There was a significant difference in the distribution of the number of non-breathing-related steps errors among the three devices (P<0.001), and further paired comparisons found that significant difference between HAN and TUR (P <0.001), and HAN and DIS (P <0.001).

Abbreviations: DPI, Dry Powder Inhaler; HAN, HandiHaler^®; TUR, Turbuhaler^®; DIS, Diskus^®.

Figure 3 The proportion of correct and wrong steps. (A) Patients’ technique of each step of HAN. (B) Patients’ technique of each step of TUR. (C) Patients’ technique of each step of DIS.

Notes: The step of “fast and deep inhalation” (the sixth step of HAN, the fifth step of TUR and the fourth step of DIS) was not evaluated, but the measurement of PIF was used to evaluate it.

Abbreviations: HAN, HandiHaler^®; TUR, Turbuhaler^®; DIS, Diskus^®.

Table 4 The Correctness of Use DPIs in Overall and Disease Subgroups

Variables	Total (n=85)	COPD (n=52)	Asthma (n=22)	ACO (n=11)	χ^2	P
PIF above the minimum
Yes	81 (95.3)	50 (96.2)	21 (95.5)	10 (90.9)	1.220^a	0.760
No	4 (4.7)	2 (3.8)	1 (4.5)	1 (9.1)
PIF optimal
Yes	52 (61.2)	29 (55.8)	14 (63.6)	9 (81.8)	2.670	0.263
No	33 (38.8)	23 (44.2)	8 (36.4)	2 (18.2)
Correct technique
Yes	29 (34.1)	14 (26.9)	10 (45.5)	5 (45.5)	3.084	0.214
No	56 (65.9)	38 (73.1)	12 (54.5)	6 (54.5)

Notes: Chi-square test examined whether there are significant differences in the PIF status and operation status of patients with COPD, asthma, and overlap; ^aFisher‘s exact test.

Abbreviations: ACO, asthma-COPD Overlap; BMI, body mass index; COPD, Chronic obstructive pulmonary disease; PIF, peak flow rate.

Table 5 Logistic Regression Analysis of Demographic/Clinical Measures and the Suboptimal Daily PIF

Variables	B	SE	OR (95% CI)	P
Age	0.06	0.03	1.06 (1.01–1.12)	0.030
Weight	−0.02	0.02	0.98 (0.94–1.02)	0.319
With respiratory diseases	1.89	0.90	6.59 (1.14–38.15)	0.035
Sex	−0.97	0.69	0.38 (0.10–1.48)	0.164

Notes: Logistic regression analysis found that age was a risk factor for suboptimal daily PIF (OR = 1.06, 95% CI 1.01–1.12, P=0.030). Combined with respiratory diseases was also a risk factor for suboptimal daily PIF (OR = 6.59, 95% CI 1.14–38.15, P=0.035), indicated in bold.

Abbreviations: SE, standard errors; OR, odds ratios; CI, confidence interval.

Table 6 Logistic Regression Analysis of Demographic/Clinical Measures and the Technique Misuse

Variables	B	SE	OR (95% CI)	P
Age	0.03	0.02	1.03 (0.99–1.07)	0.189
Education level	−0.47	0.23	0.63 (0.40–0.99)	0.043
Sex	0.51	0.65	1.67 (0.47–5.95)	0.429
Weight	0.02	0.02	1.02 (0.98–1.06)	0.287
With respiratory diseases	0.75	0.88	2.11 (0.38–11.76)	0.395

Notes: Logistic regression analysis found that education level was a protective factor for technique misuse; the higher the level, the lower the incidence of technique misuse (OR = 0.63, 95% CI 0.40–0.99, P=0.043), indicated in bold.

Abbreviations: SE, standard errors; OR, odds ratios; CI, confidence interval.