Reader Response: Three-Month Modified Rankin Scale as a Determinant of 5-Year Cumulative Costs After Ischemic Stroke: An Analysis of 11,136 Patients in Korea

We congratulate Drs. Kim et al.¹ on their article. Their sample was nearly 8-fold higher than preceding work from the Oxford Vascular Study, cited by the authors²; in addition, they included invaluable data on the use of recanalization therapies. It was surprising, however, that recanalization therapies did not decrease the poststroke costs but rather increased the costs in their models. We know that recanalization therapies such as thrombolysis³ and thrombectomy improve the 3-month mRS,⁴ which is the main driver of poststroke costs as confirmed in this study. If the association of recanalization therapy with costs is estimated from a model adjusted for 3-month mRS, we suspect that any decrease in the cost from this therapy would likely be “adjusted out.” Did the authors include an interaction term in their model for the interaction between 3-month mRS and recanalization therapies? Because this high-quality data set is likely to influence the perceptions of policy makers and future cost-effectiveness analyses, it would be helpful to further clarify this point.