Evaluating Patient Preferences of Maintenance Therapy for the Treatment of Chronic Obstructive Pulmonary Disease: A Discrete Choice Experiment in the UK, USA and Germany

Figures & data

Table 1 Discrete Choice Experiment (DCE) Attributes and Levels

Attribute	Level 1	Level 2	Level 3
Ease of inhaler use	Likely to make no mistakes	Likely to make some mistakes	Likely to make a lot of mistakes
Number of exacerbations per year (efficacy)	Likely to experience no exacerbations (flare-ups) in the next year	Likely to experience one exacerbation (flare-up) in the next year	Likely to experience two exacerbations (flare-ups) in the next year
Number of times per day you need to take the medication	Once a day	Twice a day	Three times a day
Number of maintenance/preventer inhalers	One inhaler	Two different inhalers	Three different inhalers
Out-of-pocket costs (USA and Germany only)	No change in cost of medication	5% decrease in cost of medication^a	10% decrease in cost of medication^a
Likelihood of side effects	Likely to experience no side effects	Likely to experience some side effects	Likely to experience a lot of side effects

Notes: ^aCost reduction relative to cost of current medication (USA and Germany only).

Abbreviations: DCE, discrete choice experiment; USA, United States of America.

Table 2 Example Discrete Choice Experiment (DCE) Choice Set

What Maintenance/Preventer Medication for COPD Would You Choose? Please Imagine You Can Choose Only One and These Were Your Only Options.
	A	B
Inhaler ease of use	Likely to make no mistakes	Likely to make a lot of mistakes
Exacerbations (flare-ups)	Likely to experience one exacerbation (flare-up) in the next year	Likely to experience two exacerbations (flare-ups) in the next year
Number of times per day you need to take medication	Once a day	Twice a day
Number of maintenance/ preventer inhalers	Three different inhalers	Two different inhalers
Out-of-pocket cost per month	5% decrease in cost of medication^a	No change in cost of medication
Side effects	Likely to experience some side effects	Likely to experience no side effects
Would You Prefer Your Choice (A or B) More Than Your Current COPD Maintenance Medication?
	Yes	No

Notes: ^aCost reduction relative to cost of current medication (USA and Germany only).

Abbreviations: COPD, chronic obstructive pulmonary disease; DCE, discrete choice experiment.

Table 3 Participant Characteristics

	Total (N=450)	UK (n=150)	USA (n=150)	Germany (n=150)
Age, Years
Median (IQR)	64.0 (58.0–71.0)	67.0 (59.0–71.0)	66.0 (59.0–73.0)	60.0 (55.0–65.0)
Sex, n (%)
Male	254 (56.4)	88 (58.7)	76 (50.7)	90 (60.0)
Female	196 (43.6)	62 (41.3)	74 (49.3)	60 (40.0)
Smoking Status, n (%)
Former	260 (57.8)	78 (52.0)	106 (70.7)	76 (50.7)
Current	179 (39.8)	69 (46.0)	39 (26.0)	71 (47.3)
Never	11 (2.4)	3 (2.0)	5 (3.3)	3 (2.0)
Time Since Diagnosis, Years
Median (IQR)	6.00 (3.0–10.0)	5.00 (3.0–10.0)	7.00 (4.0–11.0)	5.00 (3.0–10.0)
mMRC Dyspnea Scale Score,^a n (%)
0	28 (6.2)	9 (6.0)	15 (10.0)	4 (2.7)
1	177 (39.3)	56 (37.3)	65 (43.3)	56 (37.3)
2	156 (34.7)	54 (36.0)	48 (32.0)	54 (36.0)
3	71 (15.8)	23 (15.3)	18 (12.0)	30 (20.0)
4	18 (4.0)	8 (5.3)	4 (2.7)	6 (4.0)
CAT Score
Mean (SD)	22.9 (7.2)	23.3 (7.8)	21.1 (6.9)	24.2 (6.8)
Exacerbations in the Past Year, n (%)
0	157 (34.9)	53 (35.3)	54 (36.0)	50 (33.3)
1	107 (23.8)	32 (21.3)	34 (22.7)	41 (27.3)
2	105 (23.3)	38 (25.3)	31 (20.7)	36 (24.0)
≥3	81 (18.0)	27 (18.0)	31 (20.7)	23 (15.3)

Notes: ^aThe mMRC Dyspnea Scale is 0: no breathlessness except on strenuous exercise; 1: short of breath when hurrying on level ground or walking up a slight hill; 2: slower than people of the same age because of breathlessness, or need to stop for breath when walking at own pace; 3: stop for breath after walking about 100 yards or after a few minutes on level ground; 4: too breathless to leave the house or breathless when dressing.

Abbreviations: CAT, COPD Assessment Test; IQR, interquartile range; mMRC, modified Medical Research Council; SD, standard deviation; UK, United Kingdom; USA, United States of America.

Figure 1 Drivers of choice in the discrete choice experiment (DCE).

Notes: A mixed logit model was used. ^aReference: a lot of mistakes; ^bPer one exacerbation decrease per year; ^cPer reduction of one in the number of times the medication needs to be taken; ^dPer reduction of one in the number of inhalers needed; ^ePer 5% decrease in out-of-pocket costs relative to current maintenance therapy cost (not applicable to the UK); ^fReference: a lot of side effects. 
Abbreviations: CI, confidence interval; DCE, discrete choice experiment; OR, odds ratio; UK, United Kingdom; USA, United States of America.

Figure 2 Marginal rate of substitution (MRS) for a reduction in cost relative to current maintenance therapy cost.

Notes: Cost analysis not applicable to the UK. Cost reduction relative to cost of current medication. 
Abbreviations: MRS, marginal rate of substitution; UK, United Kingdom; USA, United States of America.

Figure 3 Marginal rate of substitution (MRS) for a reduction in exacerbations.

Abbreviations: MRS, marginal rate of substitution; UK, United Kingdom; USA, United States of America.

Table 4 Uptake Probability, Exacerbation Trade-Off and Willingness to Pay for a Switch from Two Inhalers Twice Daily to a Single Inhaler Once Daily

	Single Inhaler Once Daily vs Two Inhalers Twice Daily
	UK (n=150)	USA (n=150)	Germany (n=150)
Uptake probability,^a %	59	65	59
Increase in the number of exacerbations during 1 year that would be accepted to switch to a single inhaler once daily	0.46	1.29	0.39
Willingness to pay to switch to a single inhaler once daily,^b % cost increase	N/A	15.9	9.2

Notes: ^aThe probability that a patient would choose a single inhaler once daily over the reference scenario of two inhalers twice daily; ^bRelative to current maintenance therapy cost (USA and Germany only).

Abbreviations: N/A, not applicable; UK, United Kingdom; USA, United States of America.