Strengths and Limitations
DISEASE
This study has strengths, which overall lie in its randomized design and selection of an objective patient outcome as the primary end point. Additionally, the study population included not only patients with UPA but also BPA, in contrast to most previous retrospective studies focusing on unilateral disease. We also performed the AVS procedures according to accepted protocols with a high rate of cannulation success.This study also has limitations. The main limitation was that the patients’ response to ACTH could not be fully evaluated in that they either had ACTH or did not have ACTH. It is not known how many patients would have had discordant AVS results, which is the main group that causes uncertainty. If we had performed AVS both before and after ACTH stimulation and then made the treatment decision based on one or the other result (randomized), we would have even greater insight into the effect of ACTH stimulation on AVS outcomes and treatment decisions. Based on previous studies, ACTH stimulation may increase the rate of successful cannulation, so our study was designed as a superiority trial, but the actual rate of successful cannulation was higher than 92% in both groups, and we did not find that ACTH-stimulated AVS was superior to non–ACTH-stimulated AVS, which may lead to bias toward the null in superiority trials. Therefore, it may be necessary to conduct a noninferiority trial in the future to prove that non–ACTH-stimulated AVS is not inferior to ACTH-stimulated AVS. In addition, only Chinese patients were included in our study, and the generalizability of our results to other racial and ethnic groups requires further study.