To determine the effectiveness of pharmacologic prophylaxis in preventing clinically relevant venous thromboembolic (VTE) events and deaths after surgery. The Surgical Care Improvement Project recommends that VTE pharmacologic prophylaxis be given within 24 hours of the operation. The bulk of evidence supporting this recommendation uses radiographic end points.

The Surgical Care and Outcomes Assessment Program is a Washington State quality improvement initiative with data linked to hospital admission/discharge and vital status records. We compared the rates of death, clinically relevant VTE, and a composite adverse event (CAE) in the 90 days after elective, colon/rectal resections, based on receipt of pharmacologic prophylaxis (within 24 hours of surgery) at 36 Surgical Care and Outcomes Assessment Program hospitals (2005–2009).

Of 4,195 (mean age 61.1 ± 15.6 years; 54.1% women) patients, 56.5% received pharmacologic prophylaxis. Ninety-day death (2.5% vs 1.6%; p = 0.03), VTE (1.8% vs 1.1%; p = 0.04), and CAE (4.2% vs 2.5%; p = .002) were lower in those who received pharmacologic prophylaxis. After adjustment for patient and procedure characteristics, the odds were 36% lower for CAE (odds ratio = 0.64; 95% CI, 0.44−0.93) with pharmacologic prophylaxis. In any given quarter, hospitals where patients more often received pharmacologic prophylaxis (highest tertile of use) had the lowest rates of CAE (2.3% vs 3.6%; p = 0.05) compared with hospitals in the lowest tertile.

Using clinical end points, this study demonstrates the effectiveness of VTE pharmacologic prophylaxis in patients having elective colorectal surgery. Hospitals that used pharmacologic prophylaxis more often had the lowest rates of adverse events.