Treatment effect on ordinal functional outcome using piecewise multistate Markov model with unobservable baseline: an application to the modified Rankin scale

Cost-effectiveness of endovascular thrombectomy with alteplase versus endovascular thrombectomy alone for acute ischemic stroke secondary to large vessel occlusion

BACKGROUND

Recent randomized trials have suggested that endovascular thrombectomy (EVT) alone may provide similar functional outcomes as the current standard of care, EVT combined with intravenous alteplase treatment, for acute ischemic stroke secondary to large vessel occlusion. We conducted an economic evaluation of these 2 therapeutic options.

METHODS

We constructed a decision analytic model with a hypothetical cohort of 1000 patients to assess the cost-effectiveness of EVT with intravenous alteplase treatment versus EVT alone for acute ischemic stroke secondary to large vessel occlusion from both the societal and public health care payer perspectives. We used studies and data published in 2009-2021 for model inputs, and acquired cost data for Canada and China, representing high- and middle-income countries, respectively. We calculated incremental cost-effectiveness ratios (ICERs) using a lifetime horizon and accounted for uncertainty using 1-way and probabilistic sensitivity analyses. All costs are reported in 2021 Canadian dollars.

RESULTS

In Canada, the difference in quality-adjusted life-years (QALYs) gained between EVT with alteplase and EVT alone was 0.10 from both the societal and health care payer perspectives. The difference in cost was $2847 from a societal perspective and $2767 from the payer perspective. In China, the difference in QALYs gained was 0.07 from both perspectives, and the difference in cost was $1550 from the societal perspective and $1607 from the payer perspective. One-way sensitivity analyses showed that the distributions of modified Rankin Scale scores at 90 days after stroke were the most influential factor on ICERs. For Canada, compared to EVT alone, the probability that EVT with alteplase would be cost-effective at a willingness-to-pay threshold of $50 000 per QALY gained was 58.7% from a societal perspective and 58.4% from a payer perspective. The corresponding values for at a willingness-to-pay threshold of $47 185 (3 times the Chinese gross domestic product per capita in 2021) were 65.2% and 67.4%.

INTERPRETATION

For patients with acute ischemic stroke due to large vessel occlusion eligible for immediate treatment with both EVT alone and EVT with intravenous alteplase treatment, it is uncertain whether EVT with alteplase is cost-effective compared to EVT alone in Canada and China.

Repeated Measures of Modified Rankin Scale Scores to Assess Functional Recovery From Stroke: AFFINITY Study Findings

Background

Function after acute stroke using the modified Rankin Scale (mRS) is usually assessed at a point in time. The analytical implications of serial mRS measurements to evaluate functional recovery over time is not completely understood. We compare repeated‐measures and single‐measure analyses of the mRS from a randomized clinical trial.

Methods and Results

Serial mRS data from AFFINITY (Assessment of Fluoxetine in Stroke Recovery), a double‐blind placebo randomized clinical trial of fluoxetine following stroke (n=1280) were analyzed to identify demographic and clinical associations with functional recovery (reduction in mRS) over 12 months. Associations were identified using single‐measure (day 365) and repeated‐measures (days 28, 90, 180, and 365) partial proportional odds logistic regression. Ninety‐five percent of participants experienced a reduction in mRS after 12 months. Functional recovery was associated with age at stroke <70 years; no prestroke history of diabetes, coronary heart disease, or ischemic stroke; prestroke history of depression, a relationship partner, living with others, independence, or paid employment; no fluoxetine intervention; ischemic stroke (compared with hemorrhagic); stroke treatment in Vietnam (compared with Australia or New Zealand); longer time since current stroke; and lower baseline National Institutes of Health Stroke Scale & Patient Health Questionnaire‐9 scores. Direction of associations was largely concordant between single‐measure and repeated‐measures models. Association strength and variance was generally smaller in the repeated‐measures model compared with the single‐measure model.

Conclusions

Repeated‐measures may improve trial precision in identifying trial associations and effects. Further repeated‐measures stroke analyses are required to prove methodological value.

Registration

URL: http://www.anzctr.org.au; Unique identifier: ACTRN12611000774921.