Cost-effectiveness of stent-retriever thrombectomy in combination with IV t-PA compared with IV t-PA alone for acute ischemic stroke in the UK

Figures & data

Figure 1. Diagram of model structure.

Table 1. Clinical data input—clinical efficacy (acute phase).

Acute phaseclinical inputs	Stent retriever + IV-tPA (n = 98)	IV-tPA alone(n = 93)	Reference
Probability of
mRS 0 at 7 days	16.3%	5.4%	SWIFT PRIME^10
mRS 1 at 7 days	19.4%	7.5%
mRS 2 at 7 days	9.18%	6.5%
mRS 3 at 7 days	11.2%	10.8%
mRS 4 at 7 days	14.3%	24.7%
mRS 5 at 7 days	27.6%	39.8%
Death at 7 days	2.0%	5.4%
mRS 0 at 90 days	17.4%	8.6%
mRS 1 at 90 days	25.5%	10.8%
mRS 2 at 90 days	17.4%	16.1%
mRS 3 at 90 days	12.2%	17.2%
mRS 4 at 90 days	15.3%	21.5%
mRS 5 at 90 days	3.1%	12.9%
Death at 90 days	9.2%	12.9%
Symptomatic ICH	0.0%	3.1%
Vasospasm	15.3%	0.0%

ICH, intracranial hemorrhage; mRS, modified Rankin scale (scores range from 0–6, with 0 indicating no symptoms, 1 no clinically significant disability (able to carry out all usual activities, despite some symptoms), 2 slight disability (able to look after own affairs without assistance but unable to carry out all previous activities), 3 moderate disability (requires some help but able to walk unassisted), 4 moderately severe disability (unable to attend to bodily needs without assistance and unable to walk unassisted), 5 severe disability (requires constant nursing care and attention, bedridden, and incontinent), and 6 death).

Table 2. Clinical data input—mortality and recurrent stroke.

Mortality and recurrent stroke	Mean and 95% CI	Reference
Relative risk of dying
mRS 0	1.00	Slot et al 2009^31 Assumed mRS 0 has equal risk of dying as the general population.
mRS 1	1.00
mRS 2	1.12 (0.82, 1.56)
mRS 3	1.66 (1.24, 2.23)
mRS 4	1.92 (1.14, 2.61)
mRS 5	2.57 (1.92, 3.43)
Probability of recurrent stroke
90 days to 1 year	4.91% (NR)	Mohan et al 2011^20
1 year +	2.01% (NR)

mRS, modified Rankin Scale (assessment of global disability range from 0 (no symptoms) to 6 (death)); CI, confidence interval.

Table 3. Clinical data input—clinical efficacy (rehabilitation phase).

Rehabilitation transition probabilities (scenario analysis only)	Deteriorate	Maintain	Improve	Reference
mRS 0	0.0%	100.0%	0.0%	Jung et al.^21 Assumed patients could not improve mRS following a recurrent stroke
mRS 1	6.7%	40.0%	53.3%
mRS 2	14.3%	28.3%	57.4%
mRS 3	10.0%	40.0%	50.0%
mRS 4	0.0%	62.5%	37.5%
mRS 5	0.0%	71.4%	28.6%

mRS, modified Rankin Scale (assessment of global disability range from 0 (no symptoms) to 6 (death)); NB, these data inputs are not applied in the base case.

Table 4. Treatment costs of stent retriever and IV-tPA.

Item	Unit cost	Reference	Unit	Reference
Solitaire^a
Stent retriever	£3190.00	Covidien internal pricing	1.20	Current practice and expertclinical opinion
Catheter/support kit	£920.00	Covidien internal pricing	1.00	Expert clinical opinion
Procedure Pack	£35.00	Covidien internal pricing	1.00	Expert clinical opinion
Drapes/Gowns/Gloves	£80.00	Covidien internal pricing	1.00	Expert clinical opinion
Sheath	£15.00	Expert clinical opinion	1.00	Expert clinical opinion
Interventional Suite	£150.00	Expert clinical opinion	3.00	Expert clinical opinion
Anesthetist	£157.00	Expert clinical opinion (cost not available in PSSRU)	4.00
Anesthetist assistant	£58.00	PSSRU^17 (Nurse team manager)	4.00
Radiographer	£58.00	PSSRU^17 (Nurse team manager)	3.00
Consultant Interventional Neuroradiologist	£140.00	PSSRU^17 (Medical consultant)	3.00
Registrar	£60.00	PSSRU^17 (Registrar)	3.00
Nurse (band 7)	£58.00	PSSRU^17 (Nurse team manager)	3.00
Scrub nurse (band 5)	£49.00	PSSRU^17 (Nurse team leader)	3.00
IV t-PA^a
Nurse activates stroke team	£49.00	PSSRU^17 (Nurse team leader)	0.08	Alteplase STA^16
Stroke team assessment (Registrar grade)	£60.00	PSSRU^17 (Registrar)	0.50
Blood test	£5.23	ISD Scotland^24	1.00
Registrar accompanies patient to CT scan	£60.00	PSSRU^17 (Registrar)	1.00
Consultant reviews CT results and discusses with relatives	£140.00	PSSRU^17 (Medical consultant)	0.50
Nurse assessment	£58.00	PSSRU^17 (Nurse team manager)	0.08
IV t-PA infusion (Registrar time)	£60.00	PSSRU^17 (Registrar)	1.25
Additional 12 routine observations	£49.00	PSSRU^17 (Nurse team leader)	1.00
1:1 care for 5 h with senior nurse	£58.00	PSSRU^17 (Nurse team manager)	5.00
Junior staff review	£60.00	PSSRU^17 (Registrar)	0.42
Overnight junior staff review	£60.00	PSSRU^17 (Registrar)	0.17
Consultant review after infusion	£140.00	PSSRU^17 (Medical consultant)	0.33
Alteplase drug costs	£576.00	British National Formulary^25	1.00
Non-thrombolytic treatment
ER Doctor Assessment	£140.00	PSSRU^17 (Medical consultant)	0.25	Assumption based on alteplase STA^16
Blood test	£5.23	ISD Scotland^24	1.00
CT scan (brain imaging)	£90.55	NHS Reference Costs^26	1.00
Nurse to accompany to CT scan	£49.00	PSSRU^17 (Nurse team leader)	1.00
Nurse assessment	£49.00	PSSRU^17 (Nurse team leader)	0.08
Routine nurse observation (4 in 24 h)	£49.00	PSSRU^17 (Nurse team leader)	0.33
Junior staff review	£60.00	PSSRU^17 (Registrar)	0.21
Consultant review at 24 h	£140.00	PSSRU^17 (Medical consultant)	0.25

CT, computed tomography; ER, emergency room, PSSRU, Personal Social Services Research Unit.

^a Please note that the non-thrombolytic treatment cost was included in both the stent retriever and IV-tPA treatment costs.

Table 5. Acute and long-term costs of acute ischemic stroke by mRS.

	Mean acute costs (SD)	Mean annual long-term costs (SD)	Reference
mRS 0	£3145 (£8 333)	£2846 (£3 998)	Luengo-Fernandez et al.^27 - weight of 0.85, expert clinical opinion
mRS 1	£3700 (£8 333)	£3348 (£3 998)	Luengo-Fernandez et al.^27 - weight of 1.00, expert clinical opinion
mRS 2	£4255 (£8 333)	£3850 (£3 998)	Luengo-Fernandez et al.^27 - weight of 1.15, expert clinical opinion
mRS 3	£16,409 (£20 657)	£13,697 (£8 343)	Luengo-Fernandez et al.^27 - weight of 0.85, expert clinical opinion
mRS 4	£22,200 (£20 657)	£18,532 (£8 343)	Luengo-Fernandez et al.^27 - weight of 1.15, expert clinical opinion
mRS 5	£26,367 (£17 704)	£30,093 (£16 209)	Luengo-Fernandez et al.^27
mRS 6 (cost of death)	£3328 (£3 055)	—	Luengo-Fernandez et al.^27

mRS, modified Rankin Scale (assessment of global disability range from 0 (no symptoms) to 6 (death)); SD, standard deviation.

Table 6. Utility data inputs.

Disability level	Utility value, Mean (SD)	Reference
mRS 0	0.936 (0.127)	Rivero-Arias et al.^29
mRS 1	0.817 (0.183)
mRS 2	0.681 (0.211)
mRS 3	0.558 (0.284)
mRS 4	0.265 (0.294)
mRS 5	−0.054 (0.264)
mRS 6	0 (N/A)

mRS, modified Rankin Scale (assessment of global disability range from 0 (no symptoms) to 6 (death)); SD, standard deviation.

Table 7. Base case results of the cost-effectiveness of Stent retriever + IV t-PA vs IV t-PA alone (discounted lifetime costs and QALYs per patient).

Parameter	IV t-PA + Stent retriever	IV t-PA alone	Incremental
Treatment costs	£8480	£1443	£7037
Adverse event costs	£2.01	£2.70	−£0.69
Acute costs	£10,974	£15,183	−£4210
Long-term care costs	£86,137	£123,057	−£36,920
Recurrent stroke costs	£4729	£3826	£904
Total costs	£110,322	£143,512	−£33,190
Total QALYs	7.01	4.70	2.31
ICER			Dominant
Net benefit			£79,402
Outcomes at 1 year
Total costs	£25,734	£25,672	£62
Total QALYs	0.55	0.39	0.17
ICER			£369
Net benefit			£3323
Outcomes at 2 years
Total costs	£33,005	£36,537	−£3531
Total QALYs	1.09	0.76	0.33
ICER			Dominant
Net benefit			£10,104
Outcomes at 5 years
Total costs	£52,757	£65,772	−£13,016
Total QALYs	2.54	1.78	0.77
ICER			Dominant
Net benefit			£28,334
Disease specific outcomes			Cost
Additional cost per mRS saved at 90 days (average)			−£33,486
Additional cost per additional independent person at 90 days			−£132,064
Cost saved by being mRS 0 rather than mRS 1 at 90 days			£6836
Cost saved by being mRS 1 rather than mRS 2 at 90 days			£5248
Cost saved by being mRS 2 rather than mRS 3 at 90 days			£111,209
Cost saved by being mRS 3 rather than mRS 4 at 90 days			£47,290
Cost saved by being mRS 4 rather than mRS 5 at 90 days			£91,796

ICER, incremental cost-effectiveness ratio; mRS, modified Rankin Scale (assessment of global disability range from 0 (no symptoms) to 6 (death); QALY, quality-adjusted life year.

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