Comparison of benefit–risk preferences of patients and physicians regarding cyclooxygenase-2 inhibitors using discrete choice experiments

Figures & data

Table 1 Treatment attributes and levels of cyclooxygenase-2 inhibitors

Attributes	Definition	Level (%)	Variable name	Coefficients
Benefits
Reduction in pain	Reduction rate in the WOMAC pain scale from baseline	20	PAI1	βPAI1
		45	PAI2	βPAI2
		55	PAI3	βPAI3
Improvement of physical function	Reduction rate in WOMAC physical function scale from baseline	15	FUN1	βFUN1
		35	FUN2	βFUN2
		45	FUN3	βFUN3
Risks
Upper GI complications	Chance of upper GI complication (gastric ulcer, GI bleeding, or perforation)	1 (1 of 100 patients)	GI1	βGI1
		3 (3 of 100 patients)	GI2	βGI2
		5 (5 of 100 patients)	GI3	βGI3
CV adverse events	Chance of CV adverse events (angina, myocardial infarction, congestive heart failure, stroke)	0.4 (4 of 1,000 patients)	CV1	βCV1
		1.2 (12 of 1,000 patients)	CV2	βCV2
		4 (40 of 1,000 patients)	CV3	βCV3

Note: _1,2 and ₃ indicate the three evaluation levels.

Abbreviations: CV, cardiovascular; FUN, reduction rate in WOMAC physical function scale from baseline; GI, gastrointestinal; PAI, reduction rate in the WOMAC pain scale from baseline; WOMAC, Western Ontario and McMaster Universities Arthritis Index.

Figure 1 Example of a choice set.

Figure 2 Flowchart for subject selection process.

Abbreviation: DCE, discrete choice experiment.

Table 2 Respondents’ baseline characteristics

Characteristics	Analysis included respondents (%)
Patient group	98 (100)
Age (mean ± SD)	55.7±7.8
Sex
Male	30 (31)
Female	68 (69)
Diagnosed disease
Osteoarthritis	62 (63)
Rheumatoid arthritis	29 (30)
Both osteoarthritis and rheumatoid arthritis	7 (7)
Experienced adverse event related to treatment during the treatment process
None	37 (38)
Gastrointestinal disease	40 (41)
Cardiovascular disease	14 (14)
More than two diseases	5 (5)
Others	2 (2)
Physicians (orthopedists)	60 (100)
Age (mean ± SD)	40.0±4.9
Sex
Male	59 (98)
Female	1 (2)
Underwent treatment for arthritis
<5 years	9 (15)
5–10 years	24 (40)
>10 years	27 (45)

Note: Data is presented as number (%) unless otherwise stated.

Abbreviation: SD, standard deviation.

Table 3 Preferences of patient group and physician group as estimated by the regression model

Attribute		Patient group (n=98)			Physician group (n=60)			Comparison
		Coefficient	SE	P-value	Coefficient	SE	P-value	P-value
PAI
20%	βPAI1	0.6	0.12	<0.0001	−1.5	0.16	<0.0001	0.6
45%	βPAI2	0.1	0.07	<0.0001	0.5	0.09	<0.0001	0.1
55%	βPAI3	0.5	0.08	<0.0001	1.0	0.129	<0.0001	0.5
FUN
15%	βFUN1	0.1	0.13	<0.0001	−0.8	0.13	<0.0001	0.1
35%	βFUN2	0.0	0.07	0.1305	0.4	0.10	0.0001	0.0
45%	βFUN3	0.0	0.10	<0.0001	0.4	0.09	<0.0001	0.0
GI
1% (1 of 100 patients)	βGI1	0.0	0.09	<0.0001	0.5	0.10	<0.0001	0.0
3% (3 of 100 patients)	βGI2	0.5	0.06	0.0017	0.3	0.09	0.0029	0.5
5% (5 of 100 patients)	βGI3	0.1	0.10	<0.0001	−0.8	0.12	<0.0001	0.1
CV
0.4% (4 of 1,000 patients)	βCV1	0.0	0.10	<0.0001	1.1	0.11	<0.0001	0.0
1.2% (12 of 1,000 patients)	βCV2	0.6	0.07	0.0106	0.2	0.08	0.004	0.6
4.0% (40 of 1,000 patients)	βCV3	0.0	0.06	<0.0001	−1.3	0.10	<0.0001	0.0
Model fit statistics			Without covariates	With covariates		Without covariates	With covariates
AIC			2,037.85	1,669.75		1,247.67	900.83
SC			2,037.85	1,717.64		1,247.67	944.79
−2 Log L			2,037.85	1,653.75		1,247.67	884.83
Testing global null hypothesis: Beta=0			Chi-square	P-value > chi-square		Chi-square	P-value > chi-square
Likelihood ratio			384.10	<0.0001		362.84	<0.0001
Score			333.69	<0.0001		314.70	<0.0001
Wald’s equation			230.43	<0.0001		213.30	<0.0001

Note: _1,2 and ₃ indicate the three evaluation levels.

Abbreviations: AIC, Akaike information criterion; CV, cardiovascular; FUN, reduction rate in WOMAC physical function scale from baseline; GI, gastrointestinal; PAI, reduction rate in the WOMAC pain scale from baseline; SC, Schwarz criterion; SE, standard error; WOMAC, Western Ontario and McMaster Universities Arthritis Index.

Figure 3 Preference weights for benefit–risk attributes for patient and physician groups.

Notes: The differences between adjacent weights indicate the relative importance of moving from one level of an attribute to an adjacent level of that attributes.
Abbreviations: CV, cardiovascular; FUN, reduction rate in WOMAC physical function scale from baseline; GI, gastrointestinal; PAI, reduction rate in the WOMAC pain scale from baseline; WOMAC, Western Ontario and McMaster Universities Arthritis Index.

Figure 4 Relative importance of benefit–risk attributes for patient and physician groups.

Abbreviations: CV, cardiovascular; FUN, reduction rate in WOMAC physical function scale from baseline; GI, gastrointestinal; PAI, reduction rate in the WOMAC pain scale from baseline; WOMAC, Western Ontario and McMaster Universities Arthritis Index.

Table 4 MAR for patient and physician groups

Improvement in benefit	Patient group (n=98)		Physician group (n=60)
	GI (mean, [95% CI])	CV (mean, [95% CI])	GI (mean, [95% CI])	CV (mean, [95% CI])
PAI
20%–45%	0.7 (0.65–0.67)	0.6 (0.63–0.65)	0.8 (0.74–0.76)	0.8 (0.79–0.81)
45%–55%	1.5 (1.46–1.48)	1.4 (1.42–1.44)	0.6 (0.57–0.59)	0.6 (0.61–0.63)
20%–55%	2.1 (2.11–2.15)	2.1 (2.05–2.09)	1.3 (1.32–1.34)	1.4 (1.41–1.45)
FUN
15%–35%	0.2 (0.20–0.20)	0.2 (0.20–0.20)	0.5 (0.52–0.54)	0.6 (0.56–0.58)
35%–45%	1.8 (1.79–1.81)	1.7 (1.72–1.76)	0.1 (0.04–0.06)	0.1 (0.05–0.07)
15%–45%	2.0 (1.99–2.01)	1.9 (1.92–1.96)	0.6 (0.57–0.59)	0.6 (0.61–0.63)

Abbreviations: CI, confidence interval; CV, cardiovascular; FUN, reduction rate in WOMAC physical function scale from baseline; GI, gastrointestinal; MAR, maximum acceptable risk; PAI, reduction rate in the WOMAC pain scale from baseline; WOMAC, Western Ontario and McMaster Universities Arthritis Index.