Impact of diabetes on carotid artery revascularization.

OBJECTIVE: Diabetes has been suggested as a marker of higher operative risk during carotid artery revascularization. The aim of this study was to summarize the current evidence comparing the effectiveness of carotid revascularization in diabetic vs nondiabetic patients.

METHODS: We conducted a systematic search of MEDLINE, Embase, and the Cochrane Library databases (1946 to January 2015) for all studies comparing the clinical outcomes of diabetic vs nondiabetic patients who underwent carotid endarterectomy (CEA) or carotid artery stenting (CAS) in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two authors independently reviewed the studies for inclusion and quality and extracted the data. A third author validated study selection and data extraction. We calculated treatment effects as odds ratios (ORs) and 95% confidence intervals (CIs). We quantified heterogeneity using the I(2) statistic. All pooled analyses were based on random-effects models. The predefined review protocol was registered at the International Prospective Register of Systematic Reviews (PROSPERO 2015:CRD42015015873).

RESULTS: Of the 1241 abstracts screened, we included 14 observational studies involving 16,264 patients. There was excellent agreement in study selection between the two reviewers (κ statistic, 0.83; 95% CI, 0.72-0.94). CEA was used in 10 studies, CAS was used in 3 studies, and both CEA and CAS were used in 1 study. All included studies were published after 1984, and 93% were published after 1997. Carotid revascularization in diabetic patients was associated with a higher risk of the following outcomes: perioperative stroke (OR, 1.38; 95% CI, 1.02-1.88; P = .04; I(2) =13%), death (OR, 1.94; 95% CI, 1.36-2.75; P = .0002; I(2) = 0%), composite risk of stroke or death (OR, 1.80; 95% CI, 1.32-2.47; P = .0002; I(2) = 26%), and long-term risk of death (OR, 1.57; 95% CI, 1.22-2.03; P = .0005; I(2) = 0%). No association was found between diabetes and perioperative risk of myocardial infarction (MI); composite risk of MI, stroke, or death; and long-term risk of stroke. Study quality was limited by selection bias, minimal control for confounders, and single-center retrospective design. Sensitivity analyses excluding low-quality studies did not change the effect of diabetes on the risk of stroke, death, or MI.

CONCLUSIONS: Diabetic patients are at an increased risk of perioperative stroke, death, and long-term mortality compared with nondiabetic patients who undergo carotid artery revascularization. This knowledge can help further risk stratify patients with carotid artery stenosis before treatment. Future studies should focus on evaluating which mode of revascularization (CEA or CAS) is more effective in diabetic patients with carotid artery stenosis.