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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Carotid endarterectomy plus medical therapy or medical therapy alone for carotid artery stenosis in symptomatic or asymptomatic patients: a meta-analysis

J Guay and EA Ochroch.

Review published: 2012.

Link to full article: [Journal publisher]

CRD summary

This review concluded that carotid endarterectomy was helpful in reducing the risk of stroke/death for patients with recent symptoms of carotid artery stenosis (50% or more), but had no benefit for asymptomatic patients. Despite the risks of bias identified in many included trials, the authors' conclusions reflected the evidence from a large number of patients and are probably reliable.

Authors' objectives

To compare long-term rates of stroke or death for carotid endarterectomy plus medical therapy versus medical therapy alone in patients suffering from stenosis (narrowing) of the carotid artery.

Searching

PubMed was searched up to August 2011 for articles published in English. Search terms were reported. Reference lists of retrieved articles and previously identified articles were handsearched to locate further studies.

Study selection

Randomised controlled trials (RCTs) that compared carotid endarterectomy plus medical therapy versus medical therapy alone in patients with carotid artery stenosis were eligible for inclusion. Patients could be symptomatic (a stroke or retinal infarction within the last six months) or asymptomatic (absence of symptoms of an ipsilateral stroke or a transient ischaemic attack within the last six months). Eligible outcomes were rates of death (from any cause) and all strokes (including both ischaemic and haemorrhagic).

In included trials, the proportion of men ranged from 66 to 100%. Eligibility criteria, degree of stenosis, and types of anaesthesia or surgery varied across the trials. The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST) each provided classification criteria for the degree of stenosis, specifically in relation to symptomatic patients. Most included trials administered aspirin as medical therapy, in daily doses that ranged from 80mg to 1,300mg (where reported).

The authors did not state how many reviewers selected studies for inclusion.

Assessment of study quality

Risk of bias was assessed for the following domains suggested by Cochrane Collaboration criteria: adequate sequence generation; allocation concealment; blinding of patients, personnel and outcome assessors; incomplete outcome data; selective reporting; and other bias.

The authors did not state how many reviewers performed the quality assessment.

Data extraction

Data were extracted to calculate risk ratios (RR) with 95% confidence intervals (CI) for all cause death and stroke events.

The authors did not state how many reviewers extracted the data.

Methods of synthesis

Risk ratios and 95% confidence intervals from individual trials were pooled (statistical method/model not reported) separately for symptomatic and asymptomatic populations. Statistical heterogeneity was assessed using Ι². A meta-regression analysis was performed for asymptomatic patient data to calculate log odds ratios for the relationship between effect size and year of publication; numbers needed to treat or harm were calculated on the odds ratio.

Subgroup analyses were performed for symptomatic patient data, according to percentage (degree) of stenosis.

Results of the review

Eight RCTs were included in the review (11,360 patients) comprising six trials of asymptomatic patients (5,733 patients) and two trials of symptomatic patients (5,627 patients). Mean follow-up duration ranged from 23.6 months to five years (where reported). All trials had high risk of bias for blinding of patients and personnel. Six trials had a high risk for other bias. Four trials had low risk of bias for all other quality domains assessed; four had low risk of bias for all but one of the other quality domains.

Asymptomatic patients: No significant difference was found for risk of stroke or death between two and four years follow-up among groups that received carotid endarterectomy plus medical therapy versus those that received medical therapy alone (RR 0.93, 95% CI 0.84 to 1.02; six trials; Ι²=0%). A small but significantly higher risk of death was shown among carotid endarterectomy plus medical therapy groups versus medical therapy alone groups (RR 1.14, 95% CI 1.03 to 1.25). No statistically significant relationship was found between the year of publication and the effect size (p=0.81).

Symptomatic patients: For patients with severe stenosis (50% or more using the NASCET technique, or 70% or more using the ECST technique), there was a statistically significant lower risk of stroke or death among groups that received carotid endarterectomy plus medical therapy compared with the group that received medical therapy alone from two to five years follow-up (RR 0.69, 95% CI 0.59 to 0.81, two trials, Ι²=17%). The number needed to treat was 11 patients (95% CI 8 to 17). For patients with stenosis that was not severe, no statistically significant differences in the risk of stroke or death were reported between the two groups (reported fully in paper).

Authors' conclusions

Carotid endarterectomy was helpful for reducing the risk of stroke or death in recently symptomatic patients with carotid artery stenosis of 50% or more (NASCET technique), but had no benefit for asymptomatic patients.

CRD commentary

The review question was clear and supported by sufficiently replicable inclusion criteria. The searching of only one database and restriction to articles published in English increased the possibility that relevant studies were missed. The authors did not report how many reviewers were involved at various stages of the review process, which made it difficult to ascertain risks of reviewer error and bias.

Suitable quality assessment criteria were employed; the quality was generally good for all of the included trials, although most trials had a high risk of other bias. The trial with the greatest weighting in the meta-analysis for asymptomatic populations had the lowest quality, but it was uncertain whether this might have influenced the meta-analysis findings. Trial details revealed some clinical and methodological differences between trials, although no substantial statistical heterogeneity was indicated and the differences seemed small.

Despite the risks of bias identified in many of the included trials, the authors' conclusions reflected the evidence from a large number of patients and are probably reliable.

Implications of the review for practice and research

The authors did not state any implications for further practice and research.

Funding

Not stated.

Bibliographic details

Guay J, Ochroch EA. Carotid endarterectomy plus medical therapy or medical therapy alone for carotid artery stenosis in symptomatic or asymptomatic patients: a meta-analysis. Journal of Cardiothoracic and Vascular Anesthesia 2012; 26(5): 835-844. [PubMed: 22494782]

Indexing Status

Subject indexing assigned by NLM

MeSH

Aspirin /administration & dosage; Asymptomatic Diseases /epidemiology /therapy; Carotid Stenosis /epidemiology /therapy; Endarterectomy, Carotid /methods; Humans; Life Style; Randomized Controlled Trials as Topic /methods; Treatment Outcome

AccessionNumber

12012043839

Database entry date

25/02/2013

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 22494782

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