In Reply: Cost Comparison of Microsurgery vs Endovascular Treatment for Ruptured Intracranial Aneurysms: A Propensity-Adjusted Analysis.

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To the Editor: We thank Dr Wang1 for providing a thoughtful critique of our article “Cost comparison of microsurgery vs endovascular treatment for ruptured intracranial aneurysms: a propensity-adjusted analysis.”2 Wang raises concerns that variables may potentially confound the results of our comparisons between the endovascular and microsurgical cohorts. First, Wang noted that the patients who received endovascular treatment were older than those who received microsurgical treatment and were thus at higher risk for complications associated with older age. However, there was no significant difference between the cohorts with respect to the number of complications (including deep vein thrombosis or pulmonary embolism, external ventricular drain placement, infection, vasospasm, and stroke). Second, Wang noted that the mean aneurysm size was greater in the endovascular cohort than in the microsurgical cohort. Greater aneurysm size is associated with a greater risk of recurrence, possibly necessitating multiple procedures and increased costs. However, the difference in mean aneurysm size, although statistically significant, was only 0.6 mm. Furthermore, endovascular treatment of small intracranial aneurysms tends to be more difficult (possibly involving perioperative complications, recurrence, and other challenges); therefore, more small aneurysms were treated surgically at our institutions during the study period, and this likely contributed to the larger mean aneurysm size found in the endovascular cohort.3 Third, Wang pointed out that the Hunt and Hess scores were lower and the aneurysm sizes were smaller among patients with follow-up cost data, possibly because patients with good outcomes have greater enthusiasm for and adherence to follow-up. Although this and the aforementioned concerns may have merit, a propensity score adjustment was performed to mitigate baseline differences between the cohorts. Propensity score adjustment was performed for age; sex; comorbidities; Glasgow Coma Scale score; Hunt and Hess grade; Fischer grade; aneurysm size, type, and location; and follow-up duration. Because of the observational, nonrandomized design of our study, we cannot exclude the possibility of unmeasured differences in the cohort contributing to confounding biases. However, the propensity score–adjusted analysis theoretically controlled for these potentially confounding factors. Finally, we agree that the costs of endovascular treatment are expected to continue to decrease. This trend will hopefully mitigate the differences in cost between endovascular coiling and microsurgical clipping for aneurysmal subarachnoid hemorrhage.