Diagnostic performance of computed tomography angiography in peripheral arterial disease: a systematic review and meta-analysis

CONTEXT: Computed tomography angiography (CTA) is an increasingly attractive imaging modality for assessing lower extremity peripheral arterial disease (PAD). OBJECTIVE: To determine the accuracy of CTA compared with intra-arterial digital subtraction angiography (DSA) in differentiating extent of disease in patients with PAD. DATA SOURCES AND STUDY SELECTION: Search of MEDLINE (January 1966-August 2008), EMBASE (January 1980-August 2008), and the Database of Abstracts of Reviews of Effectiveness for studies comparing CTA with intra-arterial DSA for PAD. Eligible studies compared multidetector CTA with intra-arterial DSA, included at least 10 patients with intermittent claudication or critical limb ischemia, aimed to detect more than 50% stenosis or arterial occlusion, and presented either 2 x 2 or 3 x 3 contingency tables ( <or = 50% stenosis vs > 50% stenosis or occlusion), or provided data allowing their construction. DATA EXTRACTION: Two reviewers screened potential studies for inclusion and independently extracted study data. Methodological quality was assessed by using the QUADAS instrument. DATA SYNTHESIS: Of 909 studies identified, 20 (2.2%) met the inclusion criteria. These 20 studies had a median sample size of 33 (range, 16-279) and included 957 patients, predominantly with intermittent claudication (68%). Methodological quality was moderate. Overall, the sensitivity of CTA for detecting more than 50% stenosis or occlusion was 95% (95% confidence interval [CI], 92%-97%) and specificity was 96% (95% CI, 93%-97%). Computed tomography angiography correctly identified occlusions in 94% of segments, the presence of more than 50% stenosis in 87% of segments, and absence of significant stenosis in 96% of segments. Overstaging occurred in 8% of segments and understaging in 15%. CONCLUSION: Computed tomography angiography is an accurate modality to assess presence and extent of PAD in patients with intermittent claudication; however, methodological weaknesses of examined studies prevent definitive conclusions from these data