Unruptured aneurysms: Why observational studies fall short no matter how "Big" the Data

Understanding how the research question impacts trial design: Examples from discectomy trials

BACKGROUND

Formulating a pertinent research question is of the utmost importance in clinical research. An ill-conceived question may lead to an erroneous trial design, which may adversely affect the care of patients and provide uninformative or even misleading results.

METHODS

We review the research question of a randomized trial on the timing of lumbar discectomy. We compare the resulting design with other trials, real or hypothetical, that would have been more appropriate.

RESULTS

The RCT we examine randomly allocated patients to early or delayed surgery to answer a theoretical question of the effect of time on the efficacy of surgery. The trial was interpreted to have shown that early surgery was associated with better clinical and functional outcomes as compared to delayed surgery. This conclusion is clinically misleading. Valid comparisons between groups should be performed on intent-to-treat analyses and at the same time points after randomization (and not at a fixed follow-up period after surgery). The clinically pertinent comparison is not between the theoretical efficacy of surgery performed at various times, but between surgery and conservative management in patients presenting at various times. Better-designed trials on the clinical benefits of lumbar discectomy, including the treatment of chronic sciatica, have been published.

CONCLUSION

Theoretical research questions inspired from observational data can lead to erroneous trial design. Prospective randomized trials impact practice immediately: they are unique occasions to address clinical problems and optimize care under uncertainty in real time. However, they require the research question to be formulated with great care.

Recruitment in a pragmatic randomized trial on the management of unruptured intracranial aneurysms

OBJECTIVES

The Comprehensive Aneurysm Management (CAM) study is a pragmatic trial designed to manage UIA patients within a care research framework.

METHOD

CAM is an all-inclusive study. Management options are allocated according to an algorithm combining pre-randomization and clinical judgment. Eligible patients are offered 1:1 randomized allocation of intervention versus conservative management and 1:1 randomization allocation of surgical versus endovascular treatment. Ineligible patients are registered. The primary outcome is survival without dependency (mRS<3) at 10 years. All UIA patients at one center are reported.

RESULTS

Between February 2020 and July 2021, 403 UIA patients were recruited: 179 (44%) in one of the RCTs and 224 (56%) in one of the registries. Conservative management was recommended for 205/403 patients (51%); of 198 (49%) patients considered for curative treatment, 159 (80%) were randomly allocated conservative (n=81) or curative treatment (n=78). These patients were younger and had larger aneurysms than those in the observation registry (P = .004). In 39/198 patients (20%), conservative management was not considered reasonable (17 patients were recommended endovascular, 2 surgery, and 20 the RCT comparing endovascular with surgical treatment). In total, 70 patients were recruited in the RCT comparing surgery and endovascular treatment. After informed discussion at time of consent, 141/159 patients (89%) agreed with the randomly allocated management plan, while 11% crossed-over to the alternative management option.

CONCLUSION

CAM was successfully integrated into routine practice. Meaningful conclusions can be obtained if multiple centers actively participate in the trial.

Middle Cerebral Artery Aneurysm Trial (MCAAT): A randomized care trial comparing surgical and endovascular management of MCA aneurysm patients

BACKGROUND

Whether the best management of middle cerebral artery (MCA) aneurysm patients is surgical or endovascular remains uncertain, with little evidence to guide decision-making. A randomized care trial offering MCA aneurysm patients a 50% chance of surgical and a 50% chance of endovascular management may optimize outcomes in the presence of uncertainty.

METHODS

The Middle Cerebral Artery Aneurysm Trial (MCAAT) is an investigator-initiated, multi-center, parallel group, prospective, 1:1 randomized controlled clinical trial. All adult patients with MCA aneurysms, ruptured or unruptured, amenable to surgical and endovascular treatment can be included. The composite primary outcome is 'Treatment Success': i) occlusion or exclusion of the aneurysm using the allocated treatment modality; ii) no intracranial hemorrhage during follow-up; iii) no retreatment of the target aneurysm during follow-up, iv) no residual aneurysm on angiographic follow-up and v) independence (mRS <3) at 1 year. The trial tests two versions of the same hypothesis (one for ruptured and one for unruptured MCA aneurysm patients): Surgical management will lead to a 15% absolute increase in the proportion of patients reaching Treatment Success from 55% to 70% (ruptured) or from 75% to 90% (unruptured aneurysm patients) compared to endovascular treatment (any method). In this pragmatic trial, outcome evaluations are by treating physicians, except for 1 year angiographic results which will be core lab assessed. The trial will be monitored by an independent data safety monitoring committee to assure safety of participants. MCAAT is registered at clinicaltrials.gov: NCT05161377.

CONCLUSION

Patients with MCA aneurysms can be optimally managed within a care trial protocol.