Risk factors for postoperative delirium in patients undergoing vascular surgery

Objective: Postoperative delirium (PODE) remains a common complication after vascular surgery procedures although the exact pathogenesis remains unclear, mainly because of its multifactorial character. The aim of this systematic review was to evaluate pooled data on potential risk factors for PODE in patients undergoing vascular surgery procedures. Methods: A systematic literature review was conducted conforming to established criteria to identify eligible articles published from 1990 to 2016. Eligible studies evaluated potential risk factors for PODE after vascular surgery procedures, using both univariate and multivariate analysis. PODE was defined as a disturbance of consciousness with reduced ability to focus, sustain, or shift attention after vascular surgery procedures and was diagnosed in all studies using well-established criteria. Only risk factors reported in at least four studies were included in this review. Pooled results were calculated, and further multivariate regression analysis was conducted. Results: Overall, nine studies (published from 2003 to 2015) including 2388 patients in total were evaluated (457 with and 1931 without PODE). Patients with PODE were older (73.27 vs 69.87 years; P <.0001) and showed a higher male sex rate (78.1% vs 73.5%; P = .043). Open aortic surgery was the most frequent procedure in this analysis, followed by lower limb revascularization. Patients with PODE also showed higher rates of diabetes mellitus, hypertension, cardiac disease, and neurologic disease; lower hemoglobin level; larger duration of surgery; longer hospital and intensive care unit stay; and higher blood loss. Mean age (odds ratio [ OR], 3.44; 95% confidence interval [CI], 2.933-4.034; P <.0001), hypertension (OR, 1.94; 95% CI, 1.469-2.554; P <.0001), cardiac disease (OR, 3.16; 95% CI, 2.324-4.284; P <.0001), open aortic surgery (OR, 1.74; 95% CI, 1.421-2.143; P <.0001), blood loss (OR, 1.01; 95% CI, 1.007-1.010; P <.0001), hospital stay (OR, 2.26; 95% CI, 1.953-2.614; P <. 0001), and intensive care unit stay (OR, 6.12; 95% CI, 4.699-7.957; P <.0001) were identified as the strongest risk predictors for PODE, followed by male sex, diabetes mellitus, neurologic disease, and history of smoking. However, body mass index, renal failure, preoperative hemoglobin level, and general anesthesia were not found to be risk factors for PODE in such patients. Conclusions: This study has confirmed that PODE after vascular surgery procedures is a multifactorial disease, and several independent risk factors have been identified. However, pooled data regarding the effect of PODE on primary outcomes after vascular surgery procedures are still lacking. The results of this review could contribute to the designation of future prediction models and improve prevention of PODE in these patients.