Current issues of ACP Journal Club are published in Annals of Internal Medicine


Therapeutics

Carotid endarterectomy reduced the risk for functional impairment in patients with transient ischemic attacks or partial strokes and ipsilateral high-grade carotid stenosis

ACP J Club. 1994 Sept-Oct;121:38. doi:10.7326/ACPJC-1994-121-2-038


Source Citation

Haynes RB, Taylor DW, Sackett DL, et al. Prevention of functional impairment by endarterectomy for symptomatic high-grade carotid stenosis. JAMA. 1994 Apr 27;271:1256-9.


Abstract

Objective

To examine the effect of carotid endarterectomy on functional status among patients with transient ischemic attacks (TIA) or partial strokes and ipsilateral carotid stenosis of 70% to 99%.

Design

Randomized controlled trial with a mean follow-up of 18 months.

Setting

50 neurosurgical and vascular-surgical centers in North America.

Patients

659 patients had a hemispheric TIA , transient monocular blindness, or partial stroke with 70% to 99% stenosis of the ipsilateral internal carotid artery within the preceding 120 days. Exclusion criteria included intracranial carotid stenosis more severe than the surgically accessible lesion and symptoms attributable to nonatherosclerotic disease. Follow-up was complete.

Intervention

Patients were randomly assigned to carotid endarterectomy plus medical care (n = 328) or medical care alone (n = 331). Patients in both groups received antiplatelet therapy.

Main outcome measures

Functional status was assessed using a 7-point scale (1 = normal, 4 = moderate difficulty, 7 = cannot do) comprising the following items: visual acuity for reading and ambulation; language comprehension; fluency of speech; swallowing; lower-limb function (sitting down, rising from a chair, and walking on level ground); and upper-limb function (cutting food and pouring beverages, dressing and undressing, and toileting). Patients who died were given a maximum score and included in some analyses. In addition, integrated functions (shopping [7-point scale] and visiting outside usual residence [yes or no]) were included.

Main results

Functional status declined in both groups after study entry but patients in the surgical group had more gradual declines. The mean difference in total functional status score between the 2 groups during the course of the study was 1.9 points (95% CI 0.56 to 3.3), with patients who died included in this analysis. Functional status scores favored the surgical group in all categories (P < 0.05), even after patients who died were removed from the analysis (Table).

Conclusion

Carotid endarterectomy reduced the risk for functional impairment among patients with transient ischemic attacks or partial strokes and ipsilateral high-grade carotid stenosis.

Source of funding: National Institute of Neurological Disorders and Stroke.

For article reprint: Dr. R.B. Haynes, McMaster University Medical Center, 1200 Main Street West, Room 3H7, Hamilton, Ontario L8N 3Z5, Canada. FAX 905-546-0401.


Table. Carotid endarterectomy (surgery) vs medical care in patients with transient ischemic attacks or partial strokes with ipsilateral high-grade stenosis*

Development of major impairment at a mean of 18 months Surgery Medical care RRR (95% CI) NNT (CI)
Vision 2.5% 8.1% 69% 18 (11 to 77)
Comprehension of language 0.7% 5.3% 87% 22 (13 to 77)
Fluency of speech 1.1% 9.4% 88% 12 (8 to 27)
Swallowing 0.8% 5.1% 84% 24 (13 to 167)
Lower-limb function 5.4% 11.4% 53% 17 (9 to 143)
Upper-limb function 3.1% 12.4% 75% 11 (8 to 23)
Shopping (integrated function) 4.9% 12.3% 60% 14 (8 to 48)
Visits outside usual residence (integrated function) 10.3% 20.8% 50% 10 ( 6 to 28)
Major impairment in any category† 9.8% 19.0% 48% 11 (7 to 44)

*Abbreviations defined in Glossary; CIs for NNTs calculated from data in article.
†Excludes the integrated functions of shopping and visits outside the home.


Commentary

Any surprises here? No, rather a confirmation of what we know and what we thought we knew. Strokes cause functional impairment. The important finding here is that carotid endarterectomy not only prevents stroke but preserves function compared with optimal medical treatment alone. This result may seem obvious, but we would be foolish to favor surgery over medical treatment if, for instance, strokes in the surgical group were more severe or if surgery somehow reduced function through a mechanism other than stroke.

None of the study's potential shortcomings seem likely to explain away the findings. The greatest threat is from the double unblind nature of the study. With respect to the patients, self-reports of function may be subject to greater bias than decisions about stroke occurrence. The outcomes that interest us the most may be the most difficult to measure. With respect to evaluators, neurologists are presented as potentially less biased than surgeons, but neurologists are not free of these influences (1).

Accepting that the findings are valid, are they clinically important? As reported in the article, 11 patients would need to receive carotid endarterectomy to prevent 1 from developing a major impairment as defined by the investigators. It could be concluded that prevention of any functional impairment is a worthy goal. Until we know more about costs or other general health status measures, this conclusion seems warranted.

Although it has some limitations that future studies should strive to overcome, this study represents a high standard, and we should accept no less as clinicians in deciding on a new treatment. Having effective treatments, however, should not distract us from finding ways to prevent the disease in the first place.

Will Longstreth, MD
University of WashingtonSeattle, Washington, USA


Reference

1. Noseworthy JH, Ebers GC, Vandervoort MK, et al. The impact of blinding on the results of a randomized, placebo-controlled multiple sclerosis clinical trial. Neurology. 1994;44:16-20.