Article Figures & Tables
Figures
- Figure 1
Decision analytic model of mechanical thrombectomy plus intravenous thrombolysis versus intravenous thrombolysis alone for acute ischemic stroke. AIS = acute ischemic stroke, IVT = intravenous thrombolysis, M = Markov model, mRS = modified Rankin Scale, MT = mechanical thrombectomy, RCT = randomized controlled trial.
- Figure 2
Flow chart of calibration for time-dependent transition probabilities. CI = confidence interval.
- Figure 3
Cost-effectiveness plane: the incremental cost and QALY gained of mechanical thrombectomy plus intravenous thrombolysis versus intravenous thrombolysis alone. The blue triangle in the centre of the circle indicates the base case scenario. Each red circle surrounding the blue triangle represents a single result from the simulation, presenting the incremental effects and incremental costs of mechanical thrombectomy plus intravenous thrombolysis compared with intravenous thrombolysis alone. IVT = intravenous thrombosis, MT = mechanical thrombectomy, QALY = quality-adjusted life-year.
Tables
Description Mean (95% CI) Distribution (parameter 1, parameter 2) for PSA Reference Efficacy of treatment at 90 d post-AIS IVT alone strategy, % All-cause mortality 17.86 (13.89-21.82) β (64.03, 294.50) 10-14 Functional independence 28.74 (21.80-35.67) β (46.68, 115.75) 10-14 MT plus IVT strategy All-cause mortality, % 17.86 (13.89-21.82) β (64.03, 294.50) 10-14 Odds ratio of functional independence, MT plus IVT v. IVT alone* 2.39 (1.88-3.04) Log-normal (0.8713, 0.1226) 10-14 Difference in health utility relative to IVT 0.0735 (0.0137-0.1333) Normal (0.0735, 0.0305) 10,12 Calibrated monthly transition probabilities of natural history for > 3 mo after stroke Best fitting parameter set 1000 convergent parameter sets From functional independence to disability, mo 4-6 0.0321 - 17,18,20,21 7-12 0.0220 - 17,18,20,21 13-24 0.0134 - 17,18,20,21 25-36 0.0111 - 17,18,20,21 37-48 0.0093 - 17,18,20,21 49-60 0.0077 - 17,18,20,21 From disability to functional independence, mo 4-6 0.0372 - 20 7-12 0.0156 - 20 13-60 0 - Assumption** From functional independence to death, mo 4-12 0.0080 - 17,18,20,21 13-24 0.0034 - 17,18,20,21 25-36 0.0039 - 17,18,20,21 37-48 0.0043 - 17,18,20,21 49-60 0.0047 - 17,18,20,21 From disability to death, mo 4-12 0.0229 - 17,18,20,21 13-24 0.0096 - 17,18,20,21 25-36 0.0108 - 17,18,20,21 37-48 0.0122 - 17,18,20,21 49-60 0.0131 - 17,18,20,21 Health care costs, $CAD† First 3 mo after stroke Extra cost of MT treatment 15 000 γ (25, 600) 22-28 Functional independence (mRS of 0-2) 18 852 γ (25, 754.08) 29 Disability (mRS of 3-6) 57 382 γ (25, 2295.28) 29 IVT alone, weighted by health status‡ 46 308 - 22-29 MT + IVT, weighted by health status§ 53 471 - 22-29 Greater than 3 mo after stroke Functional independence (mRS of 0-2) 1 384 per month γ (25, 55.36) 29 Disability (mRS of 3-5) 3 080 per month γ (25, 123.2) 29 Health utility for > 3 mo after stroke Functional independence (mRS of 0-2) 0.71 (0.68-0.74) β (623.29, 254.58) 30 Disability (mRS of 3-5) 0.31 (0.29-0.34) β (407.26, 906.49) 30 Note: AIS = acute ischemic stroke, $CAD = Canadian dollars in 2015, CI = confidence interval, IVT = intravenous thrombolysis, mRS = modified Rankin Scale, MT = mechanical thrombectomy, PSA = probabilistic sensitivity analysis.
*Given the odds ratio of 2.39 and pooled proportion of functional independence of 0.2874, we estimated that the proportion of functional independence was 0.4908.
†Economic Burden of Ischemic Stroke study29 did not report the 95% CI or standard error (SE) of their cost estimates. We assumed the SE was equal to 20% of the mean in the probabilistic sensitivity analysis.
‡$18 852 × 0.2874 + $57 382 × 0.7126 = $46 308.
§$15 000 + $18 852 × 0.4908 + $57 382 × 0.5092 = $53 471.
¶Unless stated otherwise. **Evidence suggests that the chance of patients recovering from disability to functional independence after 1 yr after acute stroke is small.20
Description Mean Reference Inputs from ESCAPE trial, efficacy of treatment at 90 d post AIS IVT alone strategy, % All-cause mortality 19.0 14 Functional independence 29.3 14 Cost in first 3 mo, weighted by health status; $CAD 46 093 14,29 MT + IVT strategy, % All-cause mortality 10.4 14 Functional independence 53.0 14 Cost in first 3 mo, weighted by health status; $CAD 51 961 14,29 Inputs from Broderick and colleagues, severe stroke (National Institutes of Health Stroke Scale score ≥ 20) 31 IVT alone strategy, % All-cause mortality 34 31 Functional independence 14 31 Cost in first 3 mo, weighted by health status; $CAD 51 988 29,31 MT + IVT strategy All-cause mortality, % 34 Assumption* Odds ratio of functional independence, MT + IVT v. IVT alone 1.97 31 Cost in first 3 mo, weighted by health status; $CAD 63 026 29,31 Odds ratio of functional independence in subgroup patients, MT + IVT v. IVT; yr ≤ 70 3.02 10-14 > 70 1.79 10-14 Including cost for cost of end-of-life care Cost of end-of-life care for death after 90 d poststroke; $CAD 50 892 32 Note: AIS = acute ischemic stroke, $CAD = Canadian dollars in 2015, IVT = intravenous thrombolysis, mRS = modified Rankin Scale, MT = mechanical thrombectomy.
*This study31 did not find a significant difference in mortality between groups (28.8% mRS 6 in the endovascular treatment group v. 34% in the IT group). Therefore, we assumed no survival benefit for MT in this scenario analysis.
Strategy Average total costs ($CAD) Incremental cost ($CAD) QALY QALYs gained ICER* ($CAD) Base case IVT 124 419 - 1.273 - - MT + IVT 126 939 2 520 1.484 0.210 11 990 Efficacy based on ESCAPE trial14 IVT 122 901 - 1.265 - - MT + IVT 132 224 9 323 1.613 0.348 26 815 Severe stroke IVT 116 826 - 0.933 - - MT + IVT 125 517 8 691 1.039 0.106 81 651 Note: Numbers may appear inexact because of rounding. $CAD = Canadian dollars in 2015, ICER = incremental cost-effectiveness ratio, IVT = intravenous thrombolysis, MT = mechanical thrombectomy, QALY = quality-adjusted life-year.
*Incremental cost per QALY gained.
Scenario Incremental cost per QALY gained ($CAD) Base case analysis (reference) 11 990 Time horizon, yr 1 91 080 3 20 540 10 11 491 15* 12 877 MT with reduced mortality risk (odds ratio of mortality, MT + IVT v. IVT alone, 0.80) 22 891 Extra cost of MT treatment, $CAD 10 000 Dominant 20 000 35 779 Age group, yr ≤ 70 4 429 > 70 29 899 Health utility in functional independence and disability states Lower limit of 95% CI 12 366 Upper limit of 95% CI 11 809 Annual discount rate for both cost and utility, % 0 10 028 3 11 205 10 13 943 Including cost for end-of-life care for those who survive at 90 d after an acute ischemic stroke 4 212 Note: $CAD = Canadian dollars in 2015, CI = confidence interval, IVT = intravenous thrombolysis, MT = mechanical thrombectomy, QALY = quality-adjusted life-year.
*About 5.4% and 6.9% of patients were alive in the IVT alone and IVT + MT arms, respectively, at 15 yr follow-up in our model.
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