Understanding patient preferences for handheld autoinjectors versus wearable large-volume injectors

Figures & data

Table 1. Overview of study participants (N = 191) by chronic disease diagnosis and self-injection therapy status.

	Self-injection therapy status
Chronic disease	N/A	Diagnosis w/o self-injection therapy	Diagnosed w self-injection therapy
Arthritis	155	24	12
Psoriasis	159	29	3
Crohn’s Disease	167	9	15
Multiple sclerosis	170	9	21
Asthma	158	27	6
Osteoporosis	173	7	11
Diabetes	153	11	27
Cardiovascular diseases	163	24	4
Cancer	170	13	8

Table 2. Instruments used in the online survey to assess (A) patient characteristics and (B) treatment attributes as potential predictor variables of injection device preference.

Variable	Definition	Scale used	Reference (if applicable)
A. Patient Characteristics
Age	Chronological age of patient	Age in years	N.A.
Gender	Self-reported gender of patient	Female; diverse; male	N.A.
Occupational Status	Main occupation performed by patient	Fulltime employment/ Part-time employment/ Self-employed/ Job-seeking/ School-based education/ Advanced education/ Early retirement/ Retirement	N.A.
Self-injection Experience	Previous or current experience with self-injection of drugs	Never self-injected before/ Self-injecting in the past/ Currently self-injecting	N.A.
Disease status	Presence of a disease diagnosed by HCPs	Relevant disease(s) selected (multiple answers possible): Arthritis, psoriasis, Crohn’s disease, multiple sclerosis, asthma, osteoporosis, diabetes, cardiovascular diseases, cancer	N.A.
Eyesight	Self-reported visual acuity (incl. visual aid of choice, if any)	‘How would you describe your eyesight (wearing the glasses or contact lenses you usually use, if any)?’ 1 = very bad/ 2 = bad/ 3 = average/ 4 = good/ 5 = very good	[37]
Pain sensitivity	Self-reported pain-sensitivity	Visual analog scale, wording derived from pain VAS	[38]
Manual Dexterity	Self-reported impairments in manual dexterity	Score used in SF-SACRAH questionnaire	[39]
Skin Sensitivity	Self-reported average skin sensitivity	Score from ‘Sensitive 10’ questionnaire	[40]
Quality of life	Self-reported quality of life regarding physical wellbeing	Subscale ‘physical health’ of WHOQOL-BREF	[41]
B. Treatment Attributes
Injection duration	Total time required to complete injection (incl. preparation and disposal)	Handheld autoinjector: 3 min (w/o steps before and after injection: 10s) Wearable large-volume injector: 8 min/ 33 min (w/o steps before and after injection: 5 min/ 30 min)	N.A.
Injection frequency	Frequency of injection as per therapy plan	Four times per month (weekly)/ Twice per month (biweekly)/ Once per month (monthly)/ Once in three months (quarterly)	N.A.
Pain sensation	Perceived pain when injecting	Mild pain/ moderate pain	N.A.
Skin reactions	Average skin reactions to the injection process	Mild reactions/ moderate reactions	N.A.
Number of injections	Number of injections to administer required dose	3x consecutive injections using handheld autoinjector/ 1x injection using wearable large-volume device	N.A.

Table 3. Overview of the 12 pairwise choice tasks and respective treatment attributes presented to each participant in the online survey for the handheld autoinjector and wearable large-volume injector dosing options.

		Dosing option
Scenario ID	Treatment attribute at focus	Handheld autoinjector	Wearable large-volume injector
ID.1	Injection duration/ injection frequency	4x per month, 3 min	2x per month, 8 min
ID.2		4x per month, 3 min	1x per month, 8 min
ID.3		4x per month, 3 min	1x every three months, 8 min
ID.4		4x per month, 3 min	2x per month, 33 min
ID.5		4x per month, 3 min	1x per month, 33 min
ID.6		4x per month, 3 min	1x every three months, 33 min
ID.7	Repeated injections using autoinjector	3 repeated injections, 3 min	1 single injection, 8 min
ID.8		3 repeated injections, 3 min	1 single injection, 33 min
ID.9	Pain sensation/ injection duration	Fast injection (10 sec), moderate pain	Slow injection (5 min), mild pain
ID.10		Fast injection (10 sec), moderate pain	Slow injection (30 min), mild pain
ID.11	Skin reaction/ injection frequency	4x per month, mild skin reactions	2x per month, moderate skin reactions
ID.12		4x per month, mild skin reactions	1x per month, moderate skin reactions

Table 4. Descriptive statistics and correlation coefficients for participant characteristics included in the study.

Variable	M	SD	Min	Max	1	2	3	4	5
1. Age	38,13	14,78	18	77
2. Dexterity	2,41	1,68	1	8	.14 [−.00, .28]
3. Skin sensitivity	25,74	19,51	0	77,8	.01 [−.13, .15]	.61** [.51, .69]
4. Quality of life	13,33	3,72	4,57	20	−.19** [−.33, −.05]	−.57** [−.66, −.46]	−.52** [−.62, −.41]
5. Pain sensitivity	41,64	23,17	0	92	−.14 [−.27, .01]	.10 [−.05, .24]	.24** [.10, .37]	.01 [−.13, .15]
6. Visual acuity	3,78	0,85	1	5	−.18* [−.31, −.03]	−.11 [−.25, .03]	−.08 [−.22, .06]	.09 [−.05, .23]	−.17* [−.31, −.03]

Note. M and SD are used to represent mean and standard deviation, respectively. Values in square brackets indicate the 95% confidence interval for each correlation. * indicates p < .05. ** indicates p < .01.

Figure 1. Injector preference statements per disease area for the baseline scenario.

Table 5. Summary statistics for the logistic regression model based on patient characteristics with the preference for wearable large-volume injector as the response variable.

Predictor	Coeff.	S.E.	Odds Ratio
Intercept	3.064 *	1.326	21.415
			[1.657, 307.064]
Quality of life	−0.234 ***	0.067	0.791
			[0.691, 0.899]
Dexterity	0.011	0.131	1.011
			[0.779, 1.306]
Skin sensitivity	−0.011	0.011	0.989
			[0.967, 1.011]
Sex (male)	0.303	0.349	1.354
			[0.679, 2.688]
Age	−0.009	0.012	0.992
			[0.968, 1.015]
Osteoporosis (binary, yes)	−0.913	0.631	0.401
			[0.108, 1.319]
Self-injection experience (binary, yes)	−0.498	0.373	0.608
			[0.288, 1.252]
Number of observations	185
Model Fit:
${\chi }^2\left(7\right)$	17.91**
AIC	227.44
Pseudo-R^2 (Cragg-Uhler)	0.13

Note. Coeff. and S.E. are used to represent regression coefficients and their standard errors, respectively. AIC: Akaike’s Information Criterion. Values in square brackets indicate the 95% confidence interval for odds ratios. * indicates p < .05. ** indicates p < .01. *** indicates p < .001.

Figure 2. Injector preference based on varying wearable large-volume injector injection duration (8 min versus 33 min) and frequency (biweekly, monthly, and quarterly).

Table 6. Preferences for wearable large-volume injectors (WLVI) over handheld autoinjectors (HHA) for various treatment scenarios as a percentage of all preference statements (Preference statements WLVI/Total preference statements).

	Treatment attributes in focus		Injection duration WLVI		Overall
			8 min	33 min
2.A	Injection frequency (WLVI) vs Once-weekly injection (HHA)	Biweekly	44.6% (84/188)	32.1% (60/187)	38.4% (144/375)
		Monthly	61.3% (114/186)	47.1% (88/187)	54.2% (202/373)
		Quarterly	69.1% (130/188)	67.7% (126/186)	68.4% (256/374)
		Overall	58.4% (328/562)	49.1% (274/558)	53.7% (602/1120)
			8 min	33 min
2.B.	Single injection (WLVI) vs Three sequential injections (HHA)		65.2% (120/184)	46.8% (88/188)	55.9% (208/372)
			5 min	30 min
2.C.	Mild pain during the injection (WLVI) vs Moderate pain during the injection (HHA)		45.7% (86/188)	33.6% (63/187)	39.7% (149/375)
			Biweekly	Monthly
2.D.	Mild skin reaction at injection site (WLVI) vs Moderate skin reaction at injection site (HHA)		29.2% (55/188)	42.8% (80/187)	36.0% (135/375)

Abbreviations. HHA: handheld autoinjector, WLVI: wearable large-volume injector.

Table 7. Results of the mixed effects logistic regression model predicting preference for wearable large-volume injector based on treatment attributes.

	Model 1	Model 2	Model 3	Model 4
	Coeff. (S.E.)	Coeff. (S.E.)	Coeff. (S.E.)	Coeff. (S.E.)
Treatment attributes in focus (cf. Table 1)	Injection duration/ injection frequency	Multiple injections using autoinjector	Pain sensation/ injection duration	Skin reaction/ injection frequency
Scenarios covered (cf. Table 3)	ID.1 – ID.6	ID.7 – ID.8	ID.9 – ID.10	ID.11 – ID.12
Fixed effects
Intercept	−0.46 (0.37)	1.71 (0.48)***	−10.33 (0.97)***	−3.07 (1.30)*
Injection duration (33 min)^†	−1.36 (0.36)***	−1.92 (0.43)***	−10.51 (1.29)***
Injection frequency (monthly)^†	1.70 (0.35)***			1.62 (0.49)***
Injection frequency (quarterly)^†	2.54 (0.37)***
Interaction effects
Duration (33 min)^† x Frequency (monthly)^†	−0.08 (0.48)
Duration (33 min)^† x Frequency (quarterly)^†	−1.21 (0.50)*
Random effects	Std.dev.	Std.dev.	Std.dev.	Std.dev.
ID (Intercept)	3.58	3.47	42.52	4.29
R^2 within	0.11	0.06	0.02	0.03
R^2 total	0.82	0.80	1.00	0.85
AIC	1034.7	440.1	365.2	416.93

^†Dummy variables (0,1) were included for injection duration (33 min) with 0 = 8 min and 1 = 33 min injection duration, injection frequency (monthly) with 0 = biweekly and 1 = monthly injection, and injection frequency (quarterly) with 0 = 8 min and 1 = quarterly injections.

Abbreviations. AIC = Akaike’s Information Criterion. *p < .05, **p < .01, ***p < .001.

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