Elicitation of societal preferences for chronic lymphocytic leukemia’s treatments: a discrete choice experiment

Figures & data

Table 1. List of attributes and levels.

Attributes	Levels
Time elapsed before the disease reappears	24 months 36 months 48 months 60 months
How and when you take the drug	Orally, every day Intravenously, every 4 weeks Orally, every day + Intravenously, every 4 weeks
Therapy duration	6 months 1 year 2 years Continuous (until disease reappears)
Frequency of clinical checkups (at the hospital)	Every 3/6 month Monthly Three checkups per week for 5 weeks, followed by monthly checkups
Risk of diarrhea	1 in 100 people (1%) 10 in 100 people (10%) 15 in 100 people (15%) 30 in 100 people (30%)
Risk of serious infections	1 in 100 people (1%) 10 in 100 people (10%) 15 in 100 people (15%) 30 in 100 people (30%)
Risk of organ damage	None 1 in 100 people (1%) 2 in 100 people (2%) 3 in 100 people (3%)
Risk of atrial fibrillation	None 5 in 100 people (5%) 10 in 100 people (10%) 15 in 100 people (15%)
Risk of major bleedings	None 10 in 100 people (10%) 15 in 100 people (15%) 30 in 100 people (30%)
For the treatment, you are expected to contribute monthly for an amount equal to	€0 €500 €1000

Table 2. Sample descriptive characteristics.

Variable	Statistic	Value (N = 1.000)
Age	Mean (SD)	51.4 (16.7)
	Median (min; max)	52.0 (18.0; 87.0)
Age groups
18-24	N (%)	82 (8.2)
25-34		125 (12.5)
35-44		145 (14.5)
45-54		187 (18.7)
55-65		177 (17.7)
65+		284 (28.4)
Gender (male)	N (%)	480 (48.0)
Geographic area
North-West	N (%)	269 (26.9)
North-East		197 (19.7)
Centre		201 (20.1)
South		333 (33.3)
Number of GP visits/year
Max 1/year	N (%)	251 (25.1)
2-5/year		529 (52.9)
6-10/year		136 (13.6)
>10/year		84 (8.4)
Affected by at least one disease (yes)	N (%)	429 (42.9)
Affected by at least one chronic disease (yes)	N (%)	356 (35.6)
Time with chronic disease
<6 months	N (%) *	26 (7.3)
1 year		96 (27.0)
2-5 years		75 (21.1)
6-10 years		149 (41.8)
>10 years		10 (2.8)
Number of days between treatments for chronic disease	Mean (SD)	25.4 (66.7)
Number of specialist visits/year for chronic disease
Max 1/year	N (%) *	158 (44.4)
2-5/year		168 (47.2)
6-10/year		17 (4.8)
>10/year		13 (3.6)
Perception on yearly NHS cost for treating one leukemia patient
<1.000€	N (%)	25 (2.5)
1.000-5.000€		266 (26.6)
5.000-10.000€		245 (24.5)
10.000-20.000€		188 (18.8)
20.000-50.000€		121 (12.1)
>50.000€		155 (15.5)

Note. *The percentage is computed with respect to the respondents who declared to have a chronic disease.

Table 3. Results of the DCE.

		Coeff.	SE	p-value	95% CI
Time elapsed before the disease reappears (months)	Mean	0.021***	0.002	<0.001	0.018, 0.025
	SD	0.036***	0.002	<0.001	0.031, 0.040
Mode and frequency of administration
Orally, every day + Intravenously, every 4 weeks		Ref.
Orally, every day	Mean	0.190***	0.042	<0.001	0.107, 0.273
	SD	0.473***	0.067	<0.001	0.341, 0.605
Intravenously, every 4 weeks	Mean	0.054	0.064	0.399	−0.071, 0.179
	SD	0.211	0.171	0.217	−0.546, 0.124
Therapy duration
Continuous		Ref.
6 months	Mean	0.205**	0.067	0.002	0.073, 0.336
	SD	0.261**	0.082	0.001	0.101, 0.421
1 year	Mean	0.246***	0.064	<0.001	0.121, 0.371
	SD	0.073	0.113	0.522	−0.295, 0.150
2 years	Mean	0.052	0.063	0.405	−0.071, 0.175
	SD	0.204	0.121	0.091	−0.440, 0.033
Frequency of clinical checkups (at the hospital)
Three checkups per week for 5 weeks, followed by monthly checkups		Ref.
Every 3-6 months	Mean	0.237***	0.045	<0.001	0.149, 0.326
	SD	0.345***	0.079	<0.001	0.191, 0.499
Monthly	Mean	0.089*	0.042	0.035	0.006, 0.172
	SD	0.050	0.096	0.604	−0.138, 0.238
Risk of diarrhea	Mean	−0.018***	0.002	<0.001	−0.021, −0.014
	SD	0.016***	0.004	<0.001	0.009, 0.023
Risk of serious infections	Mean	−0.039***	0.002	<0.001	−0.043, −0.035
	SD	0.034***	0.003	<0.001	0.029, 0.039
Risk of organ damage	Mean	−0.220***	0.016	<0.001	−0.251, −0.188
	SD	0.172***	0.031	<0.001	0.110, 0.233
Risk of atrial fibrillation	Mean	−0.053***	0.004	<0.001	−0.060, −0.046
	SD	0.032**	0.009	0.001	0.013, 0.050
Risk of major bleeding	Mean	−0.032***	0.002	<0.001	−0.036, −0.028
	SD	0.023***	0.004	<0.001	0.016, 0.030
Monthly out-of-pocket cost	Mean	−0.001***	0.000	<0.001	−0.002, −0.001
	SD	0.002***	0.000	<0.001	0.002, 0.002

*** p < 0.001;

** p < 0.01;

* p < 0.05.

Abbreviations: CI: confidence interval. SD: standard deviation. SE: standard error.

Note: To facilitate interpretation, the negative signs of the original results for SD coefficients have been converted to positive values.

Figure 1. WTP estimates (€/month) for changes in attributes’ levels.

Note. Non-significant results are reported with a striped pattern. Grey bars represent the 95% confidence intervals.

Abbreviations: n.s.: not significant

Figure 2. Levels ranking according to WTP estimates (€/month).

Note. Non-significant results are reported with a striped pattern.

Abbreviations: IV: intravenuous. m: month. n.s.: not significant. y: year. PO: oral. w: week.

Table 4. Example of WTP calculation for treatment switch (€/month).

Attributes	Treatment A	Treatment B	WTP to switch from Treatment A to Treatment B (€/month), mean (95% CI)
Median PFS	60 months		€ 0.0 (€ 0.0, € 0.0)
Mode and frequency of administration	Orally, every day + Intravenously, every 4 weeks	Orally, every day	€ 130.9 (€ 73.4, € 188.4)
Therapy duration	2 years	Continuous	-€ 35.9 (-€ 120.2, € 48.4)
Frequency of clinical checkups (at the hospital)	Three checkups per week for 5 weeks, followed by monthly checkups	Monthly	€ 61.4 (€ 4.6, € 118.2)
Risk of diarrhea (all grades)	62%	35%	€ 327.1 (€ 394.7, € 259.4)
Risk of serious infections	8%	14%	-€ 159.6 (-€ 181.6, -€ 137.7)
Risk of organ damage (all grades)	1%	0%	€ 151.3 (€ 175.7, € 126.9)
Risk of atrial fibrillation (all grades)	4%	0%	€ 145.5 (€ 169.9, € 121.1)
Risk of major bleeding (all grades)	2%	3%	-€ 22.0 (-€ 25.3, -€ 18.7)
Total WTP to switch from Treatment A to Treatment B			€ 598.6 (€ 491.2, € 706.0)