Renal failure as a risk factor for venous thromboembolism in critically Ill patients: a cohort study

The relationship between kidney function and venous thromboembolism (VTE) in critically ill patients is not well studied. The main objective of this study was to evaluate this relationship in patients admitted to a medical-surgical intensive care unit (ICU).

This was a retrospective study of 798 patients admitted to a tertiary-care ICU and prospectively followed for the development of clinically suspected and radiologically diagnosed deep venous thrombosis or pulmonary embolism. Patients were divided based on admission creatinine and dialysis history into five groups: normal kidney function, RIFLE classes R, I and F (combined=acute kidney injury [AKI]) and endstage renal disease (ESRD). We compared VTE prophylaxis practices and VTE incidence in these groups and evaluated renal failure as a VTE risk factor using multivariate Cox regression analysis.

Of the 798 patients, 27.2% had AKI and 10.1% had ESRD. Unfractionated heparin use was similar in the five groups but enoxaparin use was less frequent in AKI (13.4%) and ESRD (3.8%) patients compared with patients with normal kidney function (39.0%). VTE occurred in 7.6% of patients with normal renal function, 7.8% AKI patients and 2.5% ESRD patients (p=0.22). The adjusted hazard ratios for VTE compared to patients with normal kidney function were 0.35 (95% confidence interval [CI], 0.08-1.47) for RIFLE class R, 1.19 (95% CI, 0.83-1.70) for RIFLE class I, 0.82 (95% CI, 0.59-1.14) for RIFLE class F and 0.71 (95% CI, 0.49-1.02, p=0.06) for ESRD.

Neither AKI nor ESRD was an independent risk factors for critically ill patients.