Cost-effectiveness of asenapine in the treatment of schizophrenia in Canada

Figures & data

Figure 1. Model structure. Decision tree model (A) and Markov model (B). *Patients may die from any health state of the model.

Table 1. Model inputs: clinical parameters.

	Base-case		Lower bound		Upper bound
Target population20
Age at onset	40		20		N/A
Proportion of males	54.00%		N/A		75
Incidence of adverse effects19
Significant weight gain
Asenapine	19.40%		7.90%		22.50%
Olanzapine	35.80%		24.50%		44.40%
EPS-related event
Asenapine	16.30%		13.60%		18.00%
Olanzapine	8.30%		8.00%		8.80%
Risks of developing complications (OR)	Men	Women	Men	Women	Men	Women
Diabetes51,52	2.69	1.9	2.17	1.5	3.34	2.3
Hypertension53,54	1.68	1.56	1.45	1.48	1.94	1.64
CHDs55,56	1.68	1.25	1.13	1.01	2.5	1.55
Stroke57	1.02	1.02	1.01	1.01	1.03	1.03
Mortality risks
Diabetes58	1.88	1.88	1.55	1.55	2.27	2.27
Hypertension34	1.44	1.34	1	1	2.88	2.68
CHDs59,60	2.2	1.6	2	1.2	2.4	2.1
Stroke61	2.37	2.37	2.11	2.07	2.64	2.7
Utilities/disutilities
Disease-related62
SCZ	0.75		0.563		0.938
Weight gain in SCZ	−0.031		−0.046		−0.016
EPS in SCZ	−0.074		−0.09		−0.053
Weight of additional disutilities	0		0.5		1
Complications40
Type II diabetes	−0.06	−0.05	−0.08	−0.03	−0.03	−0.03
Hypertension	−0.02	0	−0.03	0.01	0	0.01
CHDs (Heart disease)	−0.07	−0.06	−0.09	−0.03	−0.05	−0.03
Effects of stroke	−0.17	−0.18	−0.23	−0.1	−0.12	−0.10
Suicide rate42	9.56	6.73	8.84	5.91	10.31	7.63

Table 2. Model inputs: costs.

	Event cost ($)
	Base-case	Lower bound	Upper bound
Treatment costs
Cost of annual treatment
Asenapine	1029.60	N/A	N/A
Olanzapine31	2401.38	2176.00	2627.00
Cost of EPS management63	60	0	N/A
Costs associated with long-term metabolic complications
Direct costs*
Diabetes	3834.77	1215.00	17,072.00
Hypertension	571	233	827
CHDs
Fatal CHDs	7093.20	775	52,617.00
CHDs (Year 1)	2481.24	818	8819.00
CHDs (Years 2–5)	1146.11	360	5795.00
Stroke
Fatal stroke	30,776.93	7362.00	34,165.00
Stroke (Year 1)	4034.86	1395.00	10,560.00
Stroke (Years 2–5)	1867.59	452	8692.00
Productivity losses33–37
Diabetes	528	396	660
Hypertension	119	89.25	148.75
CHDs	3109.00	2331.75	3886.25
Stroke	4322.00	3241.50	5402.50
Informal care39
Stroke	3770.00	2827.50	4712.50

*Estimated from RAMQ database.

Table 3. ICURs: base-case scenario and 10-year time horizon scenario/1000 individuals.

	Costs ($)	Incremental costs ($)	QALYs	Incremental QALYs	ICUR ($/QALY)
MoH perspective
Base-case scenario
Olanzapine	12,109,476	−6,249,398	3284	39.83	dominant
Asenapine	5,860,078		3324
Ten-year time horizon scenario
Olanzapine	22,378,620	−11,247,396	5791	77.62	dominant
Asenapine	11,131,225		5869
Societal perspective
Base-case scenario
Olanzapine	13,813,260	−6,281,358	3284	39.83	dominant
Asenapine	7,531,901		3324
Ten-year time horizon scenario
Olanzapine	26,488,731	−11,427,931	5791	77.62	dominant
Asenapine	15,060,800		5869

Figure 2. The cost-effectiveness plane for asenapine. ICURs located in the shaded area represent a cost-effective ratio for asenapine. ASE, asenapine; OLA, olanzapine; ARI, aripiprazole; QUE, quetiapine; ZIP, ziprasidone.

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