Research agenda: venous thromboembolism in medical-surgical critically ill patients

Evaluation of Prophylactic Heparin Dosage Strategies and Risk Factors for Venous Thromboembolism in the Critically Ill Patient

BACKGROUND

Venous thromboembolism (VTE) occurs frequently in critically ill patients without heparin prophylaxis. Although heparin prevents VTE, VTEs occur frequently despite prophylaxis. A higher heparin dosage may be more effective for preventing VTE.

METHODS

A retrospective study was conducted using the Premier Incorporated Perspective Database to evaluate comparatively the effects of different heparin prophylaxis dosing strategies in the critically ill patient. Critically ill adult patients who were mechanically ventilated for at least 1 day and had an intensive care unit (ICU) length of stay of at least 2 days were included. Patients received 5000 units of heparin either twice/day or 3 times/day. The primary outcome was development of a new VTE. Key secondary outcomes included clinically important bleeding, thrombocytopenia, and mortality. Patients were propensity matched to control for confounding. Multivariable analysis was conducted for VTE risk factors.

RESULTS

The study included 30,800 patients from 374 hospitals who were propensity matched by heparin dosage. New VTE occurred in 6.16% of patients treated with 3 times/day heparin versus 6.23% with twice/day heparin (p=0.8). No significant differences in the incidence of pulmonary embolism (0.91% vs 0.8%, p=0.29) or deep vein thrombosis (5.56% vs 5.70% p=0.59) were observed between the two types of heparin dosing. No differences were observed between the two types of heparin dosing in in-hospital mortality (15.8% vs 15.15%), bleeding (0.23% vs 0.33%), or thrombocytopenia (5.19% vs 5.34%, p>0.08 for all), respectively. Risk factors associated with VTE included intraabdominal and urinary tract infections, loop diuretics, malnutrition, obesity, thrombocytopenia, paralytics, vasopressors, female sex, peripheral vascular disease, sepsis, neutropenia, and end-stage renal disease. Antiplatelet therapy, heart failure, diabetes, and substance abuse were associated with reduced VTE (p<0.05 for all).

CONCLUSIONS

In critically ill patients, prophylactic dosing of heparin 3 times/day versus twice/day was not associated with differences in new VTE or safety outcomes. Several modifiable VTE risk factors were identified.

Adverse drug events associated with disorders of coagulation

Disorders of coagulation are common adverse drug events encountered in critically ill patients and present a serious concern for intensive care unit (ICU) clinicians. Dosing strategies for medications used in the ICU are typically developed for use in noncritically ill patients and, therefore, do not account for the altered pharmacokinetic and pharmacodynamic properties encountered in the critically ill as well as the increased potential for drug-drug interactions, given the far greater number of medications ordered. This substantially increases the risk for coagulation-related adverse reactions, such as a bleeding or prothrombotic events. Although many medications used in the ICU have the potential to cause coagulation disorders, the exact incidence will vary based on the specific medication, dose, concomitant drug therapy, ICU setting, and patient-specific comorbidities. Clinicians must strongly consider these factors when evaluating the risk/benefit ratio for a particular therapy. This review surveys recent literature documenting the risk for adverse drug reactions specific to bleeding and/or clotting with commonly used medications in the ICU.