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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].

Lower extremity arterial disease: multidetector CT angiography. Meta-analysis

MH Heijenbrok-Kal, MC Kock, and MG Hunink.

Review published: 2007.

CRD summary

This review found that multidetector computed tomographic angiography is an accurate imaging tool for the assessment of arterial stenosis in lower extremity arterial disease. The review was generally well conducted, but possible limitations of the literature search and failure to assess study quality mean that these conclusions should be interpreted with some degree of caution.

Authors' objectives

To determine the accuracy of multidetector computed tomographic (CT) angiography for the assessment of symptomatic lower extremity arterial disease.

Searching

MEDLINE, EMBASE and the Cochrane Library were searched from 2000 to April 2006; the search terms, which included a diagnostic filter, were reported. Bibliographies of review articles and cited articles were screened for additional studies. Studies published in English, Dutch, French, German or Spanish were eligible for inclusion.

Study selection

Study designs of evaluations included in the review

Diagnostic cohort studies were eligible for inclusion.

Specific interventions included in the review

Studies that evaluated multidetector CT angiographic scanners with at least two detectors were eligible for inclusion. Studies that concentrated on a specific part of a lower extremity were excluded. The arterial tracts investigated included: aorta to ankles, superior mesenteric artery to pedal arteries, celiac artery to toes, diaphragm to feet, celiac artery to 10 cm below trifurcation, L2 vertebra to calf, and xiphoid to feet. In most studies the number of sections was 4, although 2 and 16 sections were also evaluated. The section thickness ranged from 0.7 to 5 mm.

Reference standard test against which the new test was compared

Studies in which the reference standard consisted of digital subtraction angiography were eligible for inclusion. Clinically significant disease was considered to be present if at least one stenosis of 50% or greater of the luminal diameter was present per arterial segment.

Participants included in the review

Studies in which patients were referred because of clinical suspicion of peripheral arterial disease were eligible for inclusion. The mean age of the patients ranged from 53 to 71 years and 55 to 96% were men. Patients were referred for evaluation of claudication (75% overall) or critical ischaemia (25% overall).

Outcomes assessed in the review

Studies that provided sufficient information to construct a 2x2 table of test performance were eligible for inclusion. The outcomes reported in the review were the sensitivity and specificity.

How were decisions on the relevance of primary studies made?

Two reviewers independently assessed studies for inclusion. Any disagreements were resolved through consensus.

Assessment of study quality

The authors did not state that they assessed validity.

Data extraction

Two reviewers independently extracted the data using a standardised form. Data were extracted or calculated to form 2x2 tables of test performance. Data were extracted separately for the total peripheral vascular tract (the abdominal aorta through to the ankles) and by anatomic area (aortoiliac, femoropopliteal and infrapopliteal areas). Sensitivity and specificity were calculated for each set of 2x2 data. If data were reported for multiple observers, data for the first observer were selected. Any disagreements were resolved through consensus.

Methods of synthesis

How were the studies combined?

The sensitivity and specificity were pooled using a random-effects model. A summary receiver operating characteristic (SROC) analysis was conducted using the Moses-Littenberg model. Analyses were conducted for the total peripheral vascular tree and separately for the aortoiliac, femoropopliteal and infrapopliteal areas. Publication bias was investigated through visual inspection of a funnel plot based on the diagnostic odds ratio (DOR).

How were differences between studies investigated?

A meta-regression analysis was conducted by extending the SROC model to include covariates for advances in technology, image quality, patient populations and study design. The effect of each variable on the DOR was investigated. A forward stepwise regression approach was adopted, with variables kept in the model if the p-value was less than 0.05.

Results of the review

Twelve studies reporting data for 14 patient series were included (436 patients, 9,541 segments).

Total peripheral vascular tree (12 studies): the SROC plot showed that all studies reported data towards the upper left hand corner of the plot, suggesting good accuracy of the technique. The sensitivity ranged from 79 to 99% and the specificity from 83 to 99%. The pooled sensitivity and specificity were 92% (95% confidence interval, CI: 89, 95) and 93% (95% CI: 91, 95), respectively.

Aortoiliac area (3 studies): the sensitivity ranged from 92 to 100 and the specificity from 95 to 98%. The pooled sensitivity and specificity were 96% (95% CI: 92, 100) and 97% (95% CI: 94, 99), respectively.

Femoropopliteal area (3 studies): the sensitivity ranged from 97 to 98% and the specificity from 70 to 94%. The pooled sensitivity and specificity were 98% (95% CI: 96, 100) and 89% (95% CI: 80, 98), respectively.

Infrapopliteal/popliteocrural area (3 studies): two studies reported high sensitivities of 90 and 96%; the third study reported a much lower sensitivity of 43%. This study only included 7 patients with stenosis and used a CT scanner with two detectors as opposed to the four used in the majority of studies. The specificity ranged from 74 to 95% and the pooled specificity was 85% (95% CI: 69, 100).

The differences in accuracy between the three techniques investigated were not statistically significant (p>0.11).

Meta-regression analysis showed that none of the factors investigated were associated with the DOR.

The funnel plot suggested the possibility of publication bias.

Authors' conclusions

Multidetector CT is an accurate imaging tool for the assessment of arterial stenosis (50% or greater stenosis) in lower extremity arterial disease.

CRD commentary

The review addressed a focused question that was supported by clearly defined inclusion criteria. The literature search was limited by the use of a diagnostic filter (the term 'specificity') and only published studies in a number of languages were eligible for inclusion. It is therefore likely that relevant studies were missed and the review may be subject to publication and language bias. Although the possibility of publication bias was considered in the review, the test used (based on the DOR) is not appropriate for diagnostic accuracy studies. Steps were taken to minimise bias during the review process but a formal quality assessment was not conducted. The validity of the included studies, and hence the review findings, therefore remains unclear.

The synthesis was adequate but the use of more sophisticated methods of analysis would have been preferable. There was no information about heterogeneity between the studies, although based on the SROC plot this appears to have been minimal. The authors conducted a meta-regression in which the effects of a number of covariates were investigated. Given that only 12 studies were included in this review, the results of this should be interpreted with extreme caution. Overall, the authors' conclusions are supported by the results presented, but should be interpreted with some degree of caution given the possible limitations of the literature search and failure to assess study quality.

Implications of the review for practice and research

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

Funding

Netherlands Organization for Scientific Research, grant number 904-66-091.

Bibliographic details

Heijenbrok-Kal M H, Kock M C, Hunink M G. Lower extremity arterial disease: multidetector CT angiography. Meta-analysis Radiology 2007; 245(2): 433-439. [PubMed: 17848679]

Indexing Status

Subject indexing assigned by NLM

MeSH

Angiography /methods /statistics & numerical data; Angiography, Digital Subtraction /statistics & numerical data; Humans; Ischemia /epidemiology /radiography; Lower Extremity /blood supply /radiography; MEDLINE; Peripheral Vascular Diseases /epidemiology /radiography; Prevalence; Reproducibility of Results; Risk Assessment /methods; Risk Factors; Sensitivity and Specificity; Tomography, X-Ray Computed /methods /statistics & numerical data

AccessionNumber

12007003729

Database entry date

09/08/2008

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: 17848679

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