Carotid Occlusion Surgery Study (COSS)

• ClinicalTrials.gov Identifier: NCT00029146
• Recruitment Status: Terminated
• First Posted: January 9, 2002
• Results First Posted: March 26, 2012
• Last Update Posted: March 27, 2012
• Sponsor: University of North Carolina, Chapel Hill
• Collaborators: National Institute of Neurological Disorders and Stroke (NINDS); Washington University School of Medicine; University of Iowa
• Information provided by (Responsible Party): William Powers, University of North Carolina, Chapel Hill

• Study Type: Interventional
• Study Design: Allocation: Randomized; Intervention Model: Parallel Assignment; Masking: Single (Outcomes Assessor); Primary Purpose: Treatment
• Conditions: Stroke; Ischemic Attack, Transient; Cerebral Infarction
• Interventions: Procedure: extracranial-intracranial bypass surgery; Drug: best medical therapy
• Enrollment: 700

Participant Flow

Recruitment Details
Pre-assignment Details

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Period Title: Overall Study
Started	97	98
Completed	95	97
Not Completed	2	1
Reason Not Completed
Lost to Follow-up	2	1

Baseline Characteristics

Arm/Group Title		Surgical Group	Non-surgical Group	Total
Arm/Group Description		Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy	Total of all reporting groups
Overall Number of Baseline Participants		97	98	195
Baseline Analysis Population Description		[Not Specified]
Age, Categorical; Measure Type: Count of Participants; Unit of measure: Participants
	Number Analyzed	97 participants	98 participants	195 participants
	<=18 years	0 0.0%	0 0.0%	0 0.0%
	Between 18 and 65 years	76 78.4%	71 72.4%	147 75.4%
	>=65 years	21 21.6%	27 27.6%	48 24.6%
Age Continuous; Mean (Standard Deviation); Unit of measure: Years
	Number Analyzed	97 participants	98 participants	195 participants
		58 (9)	58 (9)	58 (9)
Sex: Female, Male; Measure Type: Count of Participants; Unit of measure: Participants
	Number Analyzed	97 participants	98 participants	195 participants
	Female	28 28.9%	37 37.8%	65 33.3%
	Male	69 71.1%	61 62.2%	130 66.7%
Region of Enrollment; Measure Type: Number; Unit of measure: Participants	Number Analyzed	97 participants	98 participants	195 participants
United States		93	94	187
Canada		4	4	8

Outcome Measures

1. Primary Outcome

Title	Surgical Group:Ipsilateral Ischemic Stroke in 2 Yrs From Randomization and All Stroke & Death Through 30d Post-surgery; Non-surgical Group:Ipsilateral Ischemic Stroke in 2 Yrs From Randomization and All Stroke & Death Through 30d Post-randomization
Description	2 yr Kaplan-Meier estimates of the proportions.Proportions expressed as percentages for reporting purposes. Ipsilateral ischemic stroke is defined as the clinical diagnosis of a focal neurological deficit due to cerebral ischemia clinically localizable within the internal carotid artery territory distally to the symptomatic occluded internal carotid artery that lasts for more than 24 hours. All stroke is defined as the clinical diagnosis of a focal deficit due to ischemia or hemorrhage clinically localizable to the brain that lasts for more than 24 hours. Death is of any cause.
Time Frame	within 2 yrs of randomization

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	21.0; (12.8 to 29.2)	22.7; (13.9 to 31.6)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	Rates for each group were based on product limit estimates of 2-year rates and their standard errors. The test statistic was calculated as the difference in estimated rates divided by the standard error of that difference. The 2-sided z-statistic was compared to a standard unit normal distribution.The study was terminated early for futility after 195 of the planned 372 participants were enrolled.
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.78
	Comments	[Not Specified]
	Method	2-sided z-statistic
	Comments	The difference in estimated rates divided by the standard error of that difference was compared to a standard unit normal distribution.
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	1.7
	Confidence Interval	95%; -10.4 to 13.8
	Estimation Comments	Positive indicates lower rate in surgical group

2. Secondary Outcome

Title	All Stroke
Description	2 yr Kaplan-Meier estimates of the proportions. All stroke is defined as the clinical diagnosis of a focal deficit due to ischemia or hemorrhage clinically localizable to the brain that lasts for more than 24 hours
Time Frame	within 2 yrs of randomization

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	23.4; (14.8 to 32.0)	26.9; (17.6 to 36.2)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	Rates for each group were based on product limit estimates of 2-year rates and their standard errors.
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.59
	Comments	[Not Specified]
	Method	2-sided z-statistic
	Comments	The difference in estimated rates divided by the standard error of that difference was compared to a standard unit normal distribution.
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	3.5
	Confidence Interval	(2-Sided) 95%; -9.2 to 16.1
	Estimation Comments	Positive indicates lower rate in surgical group

3. Secondary Outcome

Title	Disabling Stroke
Description	2 yr Kaplan-Meier estimates of the proportions. Disabling stroke is defined as a modified Barthel Index of <12/20 at the first scheduled return visit more than 3 months after the stroke occurred
Time Frame	within two years after randomization

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	5.9; (0.8 to 10.4)	2.4; (0 to 5.6)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	Rates for each group were based on product limit estimates of 2-year rates and their standard errors. The test statistic was calculated as the difference in estimated rates divided by the standard error of that difference.
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.27
	Comments	[Not Specified]
	Method	2-sided z-statistic
	Comments	The difference in estimated rates divided by the standard error of that difference was compared to a standard unit normal distribution.
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	-3.2
	Confidence Interval	(2-Sided) 95%; -9.0 to 2.6
	Estimation Comments	Negative indicates lower rate in non-surgical group

4. Secondary Outcome

Title	Fatal Stroke
Description	2 yr Kaplan-Meier estimates of the proportions. Fatal stroke is a stroke that in the investigator's opinion led directly to the participants death within 30 days of occurrence
Time Frame	within 2 years after randomization

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	1.0; (0 to 3.1)	2.4; (0 to 5.6)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	Rates for each group were based on product limit estimates of 2-year rates and their standard errors. The test statistic was calculated as the difference in estimated rates divided by the standard error of that difference.
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.50
	Comments	[Not Specified]
	Method	2-sided z-statistic
	Comments	The difference in estimated rates divided by the standard error of that difference was compared to a standard unit normal distribution.
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	1.3
	Confidence Interval	(2-Sided) 95%; -2.5 to 5.2
	Estimation Comments	Positive indicates lower rate in surgical group

5. Secondary Outcome

Title	Death
Description	2 yr Kaplan-Meier estimates of the proportions. Death of any cause
Time Frame	within 2 years after randomization

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	1.0; (0 to 3.1)	5.1; (0.2 to 9.9)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	Rates for each group were based on product limit estimates of 2-year rates and their standard errors. The test statistic was calculated as the difference in estimated rates divided by the standard error of that difference.
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.13
	Comments	[Not Specified]
	Method	2-sided z-statistic
	Comments	The difference in estimated rates divided by the standard error of that difference was compared to a standard unit normal distribution.
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	4.0
	Confidence Interval	(2-Sided) 95%; -1.2 to 9.7
	Estimation Comments	Positive indicates lower rate in surgical group

6. Secondary Outcome

Title	Modified Rankin 0-1
Description	Proportion with modified Rankin score, dichotomized 0 or 1 vs 2-6.The modifed Rankin (0-6) describes the degree of functional disability. A lower score indicates less functional disability.
Time Frame	at 2 years after randomization or end of trial. Worst case imputed for death and missing values

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	49.5; (39.5 to 59.4)	42.9; (33.1 to 52.7)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	[Not Specified]
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.41
	Comments	[Not Specified]
	Method	Fisher Exact
	Comments	[Not Specified]
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	-6.6
	Confidence Interval	(2-Sided) 95%; -20.6 to 7.3
	Estimation Comments	Negative indicates lower rate in non-surgical group. In this case, lower rate is worse since Rankin 0-1 indicates a good outcome.

7. Secondary Outcome

Title	Modified Rankin 0-2
Description	Proportion with Modified Rankin score at 2 yrs, dichotomized 0-2 vs 3-6. The modifed Rankin (0-6) describes the degree of functional disability. A lower score indicates less functional disability.
Time Frame	at 2 years after randomization or end of trial. Worst case imputed for death and missing values

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	70.1; (61.0 to 79.2)	74.5; (65.9 to 83.1)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	[Not Specified]
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.70
	Comments	[Not Specified]
	Method	Fisher Exact
	Comments	[Not Specified]
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	4.4
	Confidence Interval	(2-Sided) 95%; -8.2 to 16.9
	Estimation Comments	Positive indicates lower rate in surgical group In this case, lower rate is worse since Rankin 0-2 indicates a good outcome.

8. Secondary Outcome

Title	Modified Barthel Index 19-20
Description	Modified Barthel Index dichotomized 19-20 vs <= 18. The modifed Barthel Index(0-20) describes the degree of independence in day-to-day self-care activities. A higher score indicates greater independence.
Time Frame	at 2 years after randomization or end of trial. Worst case imputed for death and missing values

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Unit of Measure: percentage of participants
	70.1	71.4

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	[Not Specified]
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.85
	Comments	[Not Specified]
	Method	Fisher's Exact Test
	Comments	[Not Specified]

9. Secondary Outcome

Title	Summary SS-QOL Score
Description	Summary Stroke Specific Quality of Life score (1-4) askes how self-reported overall quality of life compares with with that before stroke. A higher score indicates is better.
Time Frame	at 2 years after randomization or end of trial. Worst case imputed for death and missing values

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Mean (95% Confidence Interval); Unit of Measure: units on a scale
	3.82; (3.60 to 4.04)	3.58; (3.37 to 3.79)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	[Not Specified]
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.13
	Comments	[Not Specified]
	Method	t-test, 2 sided
	Comments	[Not Specified]
Method of Estimation	Estimation Parameter	Mean Difference (Final Values)
	Estimated Value	-0.24
	Confidence Interval	(2-Sided) 95%; -0.54 to 0.07
	Estimation Comments	Negative indicates lower score in non-surgical group.A higher score indicates better quality of life

10. Secondary Outcome

Title	Ipsilateral Ischemic Stroke in 2 Yrs From Randomization and All Stroke & Death Through 30d Post-surgery; Non-surgical Group:Ipsilateral Ischemic Stroke in 2 Yrs From Randomization and All Stroke & Death Through 30d Post-randomization
Description	2 yr Kaplan-Meier estimates of the proportions.Proportions expressed as percentages for reporting purposes. Ipsilateral ischemic stroke is defined as the clinical diagnosis of a focal neurological deficit due to cerebral ischemia clinically localizable within the internal carotid artery territory distally to the symptomatic occluded internal carotid artery that lasts for more than 24 hours. All stroke is defined as the clinical diagnosis of a focal deficit due to ischemia or hemorrhage clinically localizable to the brain that lasts for more than 24 hours. Death is of any cause.
Time Frame	within 2 years of randomization

Outcome Measure Data

Analysis Population Description

On-treatment analysis removing four participants assigned to the surgical group who never underwent surgery and censoring on the day of surgery three participants assigned to the nonsurgical group who underwent EC-IC bypass surgery.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	93	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	20.8; (12.4 to 29.1)	22.3; (13.3 to 31.2)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	Rates for each group were based on product limit estimates of 2-year rates and their standard errors. The test statistic was calculated as the difference in estimated rates divided by the standard error of that difference.
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	0.81
	Comments	[Not Specified]
	Method	2-sided z-statistic
	Comments	The difference in estimated rates divided by the standard error of that difference was compared to a standard unit normal distribution.
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	1.5
	Confidence Interval	(2-Sided) 95%; -10.7 to 13.7
	Estimation Comments	[Not Specified]

11. Other Pre-specified Outcome

Title	Any Stroke or Death Within 30 Days After Surgery
Description	[Not Specified]
Time Frame	within 30 days after surgery

Outcome Measure Data

Analysis Population Description

Intention-to-treat. All assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy

Arm/Group Title	Surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy
Overall Number of Participants Analyzed	97
Measure Type: Number; Unit of Measure: participants
	14

12. Post-Hoc Outcome

Title	Any Stroke or Death
Description	2 yr Kaplan-Meier estimates of the proportions. Any stroke is defined as the clinical diagnosis of a focal deficit due to ischemia or hemorrhage clinically localizable to the brain that lasts for more than 24 hours. Death is of any cause.
Time Frame	within 2 years after randomization

Outcome Measure Data

Analysis Population Description

Intention to treat principle.All participants analyzed in the group to which they were originally randomized.

Arm/Group Title	Surgical Group	Non-surgical Group
Arm/Group Description:	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy	Receives best current practice medical therapy
Overall Number of Participants Analyzed	97	98
Measure Type: Number; Number (95% Confidence Interval); Unit of Measure: percentage of participants
	23.4; (14.8 to 32.0)	29.9; (20.1 to 39.8)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Surgical Group, Non-surgical Group
	Comments	Rates for each group were based on product limit estimates of 2-year rates and their standard errors. The test statistic was calculated as the difference in estimated rates divided by the standard error of that difference.
	Type of Statistical Test	Superiority or Other
	Comments	[Not Specified]
Statistical Test of Hypothesis	P-Value	.33
	Comments	[Not Specified]
	Method	2-sided z-statistic
	Comments	The difference in estimated rates divided by the standard error of that difference was compared to a standard unit normal distribution.
Method of Estimation	Estimation Parameter	Difference in estimated 2 yr rates
	Estimated Value	6.5
	Confidence Interval	(2-Sided) 95%; -6.5 to 19.6
	Estimation Comments	Positive indicates lower rate in surgical group

Adverse Events

Time Frame	Surgical group: Within 30 days after surgery for 93 operated and within 30 days after randomization for 4 not operated Non-surgical group: Within 30 days after randomization
Adverse Event Reporting Description	Only serious adverse events were assessed
Arm/Group Title	Surgical Group		Non-surgical Group
Arm/Group Description	Assigned to undergo extracranial-intracranial arterial bypass in addition to best current practice medical therapy		Receives best current practice medical therapy
All-Cause Mortality
	Surgical Group		Non-surgical Group
	Affected / at Risk (%)		Affected / at Risk (%)
Total	--/--		--/--
Serious Adverse Events
	Surgical Group		Non-surgical Group
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	14/97 (14.43%)		2/98 (2.04%)
Blood and lymphatic system disorders
Deep venous thrombosis †	1/97 (1.03%)	1	0/98 (0.00%)	0
Pulmonary embolism †	1/97 (1.03%)	1	0/98 (0.00%)	0
Cardiac disorders
Hypotension †	1/97 (1.03%)	1	0/98 (0.00%)	0
Myocardial ischemia/infarction †	1/97 (1.03%)	1	0/98 (0.00%)	0
Atrial fibrillation/flutter †	1/97 (1.03%)	1	0/98 (0.00%)	0
Endocrine disorders
Hypoglycemia †	1/97 (1.03%)	1	0/98 (0.00%)	0
Nervous system disorders
Fatal stroke †	1/97 (1.03%)	1	0/98 (0.00%)	0
Non-fatal Stroke †	13/97 (13.40%)	13	2/98 (2.04%)	2
Transient ischemic attack †	4/97 (4.12%)	4	0/98 (0.00%)	0
Epidural/subdural hematoma †	2/97 (2.06%)	2	0/98 (0.00%)	0
Seizure †	2/97 (2.06%)	2	0/98 (0.00%)	0
Respiratory, thoracic and mediastinal disorders
Respiratory distress †	2/97 (2.06%)	2	0/98 (0.00%)	0
Surgical and medical procedures
Surgical site infection †	1/97 (1.03%)	1	0/98 (0.00%)	0
† Indicates events were collected by systematic assessment
Other (Not Including Serious) Adverse Events
Frequency Threshold for Reporting Other Adverse Events	0%
	Surgical Group		Non-surgical Group
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/0		0/0

Limitations and Caveats

[Not Specified]

More Information

Certain Agreements

Principal Investigators are NOT employed by the organization sponsoring the study.

There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.

Results Point of Contact

• Name/Title: William J. Powers, MD
• Organization: University of North Carolina at Chapel HIll
• EMail: powersw@neurology.unc.edu

Publications:

Grubb RL Jr, Derdeyn CP, Fritsch SM, Carpenter DA, Yundt KD, Videen TO, Spitznagel EL, Powers WJ. Importance of hemodynamic factors in the prognosis of symptomatic carotid occlusion. JAMA. 1998 Sep 23-30;280(12):1055-60.

Derdeyn CP, Gage BF, Grubb RL Jr, Powers WJ. Cost-effectiveness analysis of therapy for symptomatic carotid occlusion: PET screening before selective extracranial-to-intracranial bypass versus medical treatment. J Nucl Med. 2000 May;41(5):800-7.

Adams HP Jr, Powers WJ, Grubb RL Jr, Clarke WR, Woolson RF. Preview of a new trial of extracranial-to-intracranial arterial anastomosis: the carotid occlusion surgery study. Neurosurg Clin N Am. 2001 Jul;12(3):613-24, ix-x.

Grubb RL Jr, Powers WJ, Derdeyn CP, Adams HP Jr, Clarke WR. The Carotid Occlusion Surgery Study. Neurosurg Focus. 2003 Mar 15;14(3):e9.

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):

Grubb RL Jr, Powers WJ, Clarke WR, Videen TO, Adams HP Jr, Derdeyn CP; Carotid Occlusion Surgery Study Investigators. Surgical results of the Carotid Occlusion Surgery Study. J Neurosurg. 2013 Jan;118(1):25-33. doi: 10.3171/2012.9.JNS12551. Epub 2012 Oct 26.

Powers WJ, Clarke WR, Grubb RL Jr, Videen TO, Adams HP Jr, Derdeyn CP; COSS Investigators. Extracranial-intracranial bypass surgery for stroke prevention in hemodynamic cerebral ischemia: the Carotid Occlusion Surgery Study randomized trial. JAMA. 2011 Nov 9;306(18):1983-92. doi: 10.1001/jama.2011.1610. Erratum in: JAMA. 2011 Dec 28;306(24):2672. Obviagele, Bruce [corrected to Ovbiagele, Bruce].

• Responsible Party: William Powers, University of North Carolina, Chapel Hill
• ClinicalTrials.gov Identifier: NCT00029146
• Other Study ID Numbers: R01NS042167; R01NS041895 ( Other Grant/Funding Number: NINDS )
• First Submitted: January 8, 2002
• First Posted: January 9, 2002
• Results First Submitted: January 17, 2012
• Results First Posted: March 26, 2012
• Last Update Posted: March 27, 2012