Changing the Rules of the Game: The Problem of Surrogate Angiographic Outcomes in the Evaluation of Aneurysm Treatments

A Pragmatic Randomized Trial Comparing Surgical Clipping and Endovascular Treatment of Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE

Surgical clipping and endovascular treatment are commonly used in patients with unruptured intracranial aneurysms. We compared the safety and efficacy of the 2 treatments in a randomized trial.

MATERIALS AND METHODS

Clipping or endovascular treatments were randomly allocated to patients with one or more 3- to 25-mm unruptured intracranial aneurysms judged treatable both ways by participating physicians. The study hypothesized that clipping would decrease the incidence of treatment failure from 13% to 4%, a composite primary outcome defined as failure of aneurysm occlusion, intracranial hemorrhage during follow-up, or residual aneurysms at 1 year, as adjudicated by a core lab. Safety outcomes included new neurologic deficits following treatment, hospitalization of >5 days, and overall morbidity and mortality (mRS > 2) at 1 year. There was no blinding.

RESULTS

Two hundred ninety-one patients were enrolled from 2010 to 2020 in 7 centers. The 1-year primary outcome, ascertainable in 290/291 (99%) patients, was reached in 13/142 (9%; 95% CI, 5%-15%) patients allocated to surgery and in 28/148 (19%; 95% CI, 13%-26%) patients allocated to endovascular treatments (relative risk: 2.07; 95% CI, 1.12-3.83; P = .021). Morbidity and mortality (mRS >2) at 1 year occurred in 3/143 and 3/148 (2%; 95% CI, 1%-6%) patients allocated to surgery and endovascular treatments, respectively. Neurologic deficits (32/143, 22%; 95% CI, 16%-30% versus 19/148, 12%; 95% CI, 8%-19%; relative risk: 1.74; 95% CI, 1.04-2.92; P = .04) and hospitalizations beyond 5 days (69/143, 48%; 95% CI, 40%-56% versus 12/148, 8%; 95% CI, 5%-14%; relative risk: 0.18; 95% CI, 0.11-0.31; P < .001) were more frequent after surgery.

CONCLUSIONS

Surgical clipping is more effective than endovascular treatment of unruptured intracranial aneurysms in terms of the frequency of the primary outcome of treatment failure. Results were mainly driven by angiographic results at 1 year.

Flow Diversion in the Treatment of Intracranial Aneurysms: A Pragmatic Randomized Care Trial

BACKGROUND AND PURPOSE

Flow diversion is a recent endovascular treatment for intracranial aneurysms. We compared the safety and efficacy of flow diversion with the alternative standard management options.

MATERIALS AND METHODS

A parallel group, prerandomized, controlled, open-label pragmatic trial was conducted in 3 Canadian centers. The trial included all patients considered for flow diversion. A Web-based platform 1:1 randomly allocated patients to flow diversion or 1 of 4 alternative standard management options (coiling with/without stent placement, parent vessel occlusion, surgical clipping, or observation) as prespecified by clinical judgment. Patients ineligible for alternative standard management options were treated with flow diversion in a registry. The primary safety outcome was death or dependency (mRS > 2) at 3 months. The composite primary efficacy outcome included the core lab-determined angiographic presence of a residual aneurysm, aneurysm rupture, progressive mass effect during follow-up, or death or dependency (mRS > 2) at 3-12 months.

RESULTS

Between May 2011 and November 2020, three hundred twenty-three patients were recruited: Two hundred seventy-eight patients (86%) had treatment randomly allocated (139 to flow diversion and 139 to alternative standard management options), and 45 (14%) received flow diversion in the registry. Patients in the randomized trial frequently had unruptured (83%), large (52% ≥10 mm) carotid (64%) aneurysms. Death or dependency at 3 months occurred in 16/138 patients who underwent flow diversion and 12/137 patients receiving alternative standard management options (relative risk, 1.33; 95% CI, 0.65-2.69; P = .439). A poor primary efficacy outcome was found in 30.9% (43/139) with flow diversion and 45.6% (62/136) of patients receiving alternative standard management options, with an absolute risk difference of 14.7% (95% CI, 3.3%-26.0%; relative risk, 0.68; 95% CI, 0.50-0.92; P = .014).

CONCLUSIONS

For patients with mostly unruptured, large, anterior circulation (carotid) aneurysms, flow diversion was more effective than the alternative standard management option in terms of angiographic outcome.

Long-term clinical and angiographic outcome of the Woven EndoBridge (WEB) for endovascular treatment of intracranial aneurysms

The Woven EndoBridge (WEB) is a well-established device for endovascular treatment of wide-necked bifurcation aneurysms. The objective was to evaluate the long-term angiographic outcome of the WEB and to identify factors that influence aneurysm occlusion. Patient, aneurysm and procedural characteristics of 213 consecutive patients treated with the WEB at three German tertiary care centers between 2011 and 2020 were retrospectively reviewed. Aneurysm occlusion was determined immediately after the procedure, at mid-term (≤ 12 months) and at long-term (> 12 months) follow-up. Among 182 included aneurysms (mean diameter: 7.0 ± 2.4, mean neck width: 4.3 ± 1.6 mm), 29.7% were ruptured. The novel WEB 17 was used in 41.8%, and 11.0% were treated in combination with coiling and/or stenting. Complete and adequate occlusions were observed in 101/155 (65.2%) and 133/155 (85.8%) at mid-term, respectively, and in 59/94 (62.8%) and 87/94 (92.6%) at long-term follow-up (median: 19 months), respectively. Among 92 patients available for both mid- and long-term follow-up, occlusion was stable in 72.8%, improved in 16.3% and worsened in 10.9%. There were no major recurrences leading to aneurysm remnants between mid- and long-term follow-up. Retreatment was performed in 10/155 (6.5%) during mid-term and in 1/94 (1.0%) during long-term follow-up. The WEB provides durable aneurysm occlusion at the long-term. Nevertheless, follow-up imaging is necessary to identify late recurrences that may occur in around 10%.

Understanding the reliability of trial outcome measures: The example of angiographic results of surgical or endovascular treatments of aneurysms

BACKGROUND

The reliability of outcome measures is of central importance in clinical research. Studies of reliability remain rare in the neurovascular field.

METHODS

A narrative review of the history (1997-2021) of reporting angiographic results of the surgical or endovascular treatments of aneurysms serves to illustrate the importance of precisely defining outcome measures. We also review how the reliability of an angiographic classification system was studied.

DISCUSSION

Outcome measures are commonly used without precise definitions. When definitions or classification systems exist, they are rarely verified for their reliability. Twenty-five years following its introduction, a classification of angiographic results of aneurysm treatments is still being studied and modified.

CONCLUSION

The reliability of outcome measures should be made a research priority if we are to practice outcome-based medical or surgical care.

Noninvasive Angiographic Results of Clipped or Coiled Intracranial Aneurysms: An Inter- and Intraobserver Reliability Study

BACKGROUND AND PURPOSE

Noninvasive angiography is commonly used to assess the outcome of surgical or endovascular treatment of intracranial aneurysms in clinical series or randomized trials. We sought to assess whether a standardized 3-grade classification system could be reliably used to compare the CTA and MRA results of both treatments.

MATERIALS AND METHODS

An electronic portfolio composed of CTAs of 30 clipped and MRAs of 30 coiled aneurysms was independently evaluated by 24 raters of diverse experience and training backgrounds. Twenty raters performed a second evaluation 1 month later. Raters were asked which angiographic grade and management decision (retreatment; close or long-term follow-up) would be most appropriate for each case. Agreement was analyzed using the Krippendorff α (α_K) statistic, and the relationship between angiographic grade and clinical management choice, using the Fisher exact and Cramer V tests.

RESULTS

Interrater agreement was substantial (α_K = 0.63; 95% CI, 0.55-0.70); results were slightly better for MRA results of coiling (α_K = 0.69; 95% CI, 0.56-0.76) than for CTA results of clipping (α_K = 0.58; 95% CI, 0.44-0.69). Intrarater agreement was substantial to almost perfect. Interrater agreement regarding clinical management was moderate for both clipped (α_K = 0.49; 95% CI, 0.32-0.61) and coiled subgroups (α_K = 0.47; 95% CI, 0.34-0.54). The choice of clinical management was strongly associated with the size of the residuum (mean Cramer V = 0.77 [SD, 0.14]), but complete occlusions (grade 1) were followed more closely after coiling than after clipping (P = .01).

CONCLUSIONS

A standardized 3-grade scale was found to be a reliable and clinically meaningful tool to compare the results of clipping and coiling of aneurysms using CTA or MRA.

Angiographic results of surgical or endovascular treatment of intracranial aneurysms: a systematic review and inter-observer reliability study

PURPOSE

Results of surgical or endovascular treatment of intracranial aneurysms are often assessed using angiography. A reliable method to report results irrespective of treatment modality is needed to enable comparisons. Our goals were to systematically review existing classification systems, and to propose a 3-point classification applicable to both treatments and assess its reliability.

METHODS

We conducted two systematic reviews on classification systems of angiographic results after clipping or coiling to select a simple 3-category scale that could apply to both treatments. We then circulated an electronic portfolio of angiograms of clipped (n=30) or coiled (n=30) aneurysms, and asked raters to evaluate the degree of occlusion using this scale. Raters were also asked to choose an appropriate follow-up management for each patient based on the degree of occlusion. Agreement was assessed using Krippendorff's α statistics (α_K), and relationship between occlusion grade and clinical management was analyzed using Fisher's exact and Cramer's V tests.

RESULTS

The systematic reviews found 70 different grading scales with heterogeneous reliability (kappa values from 0.12 to 1.00). The 60-patient portfolio was independently evaluated by 19 raters of diverse backgrounds (neurosurgery, radiology, and neurology) and experience. There was substantial agreement (α_K=0.76, 95%CI, 0.67-0.83) between raters, regardless of background, experience, or treatment used. Intra-rater agreement ranged from moderate to almost perfect. A strong relationship was found between angiographic grades and management decisions (Cramer's V: 0.80±0.12).

CONCLUSION

A simple 3-point scale demonstrated sufficient reliability to be used in reporting aneurysm treatments or in evaluating treatment results in comparative randomized trials.

Surgical or Endovascular Management of Middle Cerebral Artery Aneurysms: A Randomized Comparison

OBJECTIVE

There are few randomized data comparing clipping and coiling for middle cerebral artery (MCA) aneurysms. We analyzed results from patients with MCA aneurysms enrolled in the CURES (Collaborative UnRuptured Endovascular vs. Surgery) and ISAT-2 (International Subarachnoid Aneurysm Trial II) randomized trials.

METHODS

Both trials are investigator-led parallel-group 1:1 randomized studies. CURES includes patients with 3-mm to 25-mm unruptured intracranial aneurysms (UIAs), and ISAT-2 includes patients with ruptured aneurysms (RA) for whom uncertainty remains after ISAT. The primary outcome measure of CURES is treatment failure: 1) failure to treat the aneurysm, 2) intracranial hemorrhage during follow-up, or 3) residual aneurysm at 1 year. The primary outcome of ISAT-2 is death or dependency (modified Rankin Scale score >2) at 1 year. One-year angiographic outcomes are systematically recorded.

RESULTS

There were 100 unruptured and 71 ruptured MCA aneurysms. In CURES, 90 patients with UIA have been treated and 10 await treatment. Surgical and endovascular management of unruptured MCA aneurysms led to treatment failure in 3/42 (7%; 95% confidence interval [CI], 0.02-0.19) for clipping and 13/48 (27%; 95% CI, 0.17-0.41) for coiling (P = 0.025). All 71 patients with RA have been treated. In ISAT-2, patients with ruptured MCA aneurysms managed surgically had died or were dependent (modified Rankin Scale score >2) in 7/38 (18%; 95% CI, 0.09-0.33) cases, and 8/33 (24%; 95% CI, 0.13-0.41) for endovascular. One-year imaging results were available in 80 patients with UIA and 62 with RA. Complete aneurysm occlusion was found in 30/40 (75%; 95% CI, 0.60-0.86) patients with UIA allocated clipping, and 14/40 (35%; 95% CI, 0.22-0.50) patients with UIA allocated coiling. Complete aneurysm occlusion was found in 24/34 (71%; 95% CI, 0.54-0.83) patients with RA allocated clipping, and 15/28 (54%; 95% CI, 0.36-0.70) patients with RA allocated coiling.

CONCLUSIONS

Randomized data from 2 trials show that better efficacy may be obtained with surgical management of patients with MCA aneurysms.