Pharmacist update: Anticoagulation therapies

April 15, 2011

A roundup of information on CHA2DS2-VASc score versus CHADS2 as a thromboembolism determinant; the incidence of pulmonary embolism in knee arthroscopy patients; the increase of venous thromboembolism with antipsychotic drug use.

Key Points

Danish and United Kingdom researchers evaluated the components of the CHADS2 score and the CHA2DS2-VASc (CHA2DS2-vascular disease, age, sex category) score to determine which more accurately assessed patient risk. The study was conducted using a registry-based cohort of all patients admitted to hospitals in Denmark with atrial fibrillation. None of the patients included for analysis was taking warfarin.

The study found that the CHA2DS2-VASc scoring may be a better predictor of risk than the CHADS2 score. In patients at "low risk" (score=0), the rate of thromboembolism per 100 person years was 1.67 with CHADS2 and 0.78 with CHA2DS2-VASc at 1 year's follow-up. In patients at "intermediate risk" (score=1), this rate was 4.75 with CHADS2 and 2.01 with CHA2DS2-VASc.

Source: Olesen JB, Lip GY, Hansen ML, et al. Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: Nationwide cohort study. BMJ. 2011;342:d124.

Pulmonary embolism: A rare but serious complication of knee arthroscopy

A recently published study of patients post-arthroscopic knee surgery sought to characterize the incidence of pulmonary embolism (PE) in this patient population and risk factors associated with the development of this condition.

Researchers used a database of 418,323 outpatient knee arthroscopies performed over a period of approximately 10 years. Symptomatic PE was identified in 117 patients during the 90-day postoperative period. The incidence of PE was 2.8 events per 10,000 surgeries. The authors did not assess the rate of deep vein thrombosis (DVT).

Independent predictors of PE included age ≥40, female sex, and longer operating time. The type of surgery or anesthesia was not associated with an elevated risk.

The American College of Chest Physicians recommends prophylaxis with low-molecular-weight heparin for high-risk patients or for patients having complicated surgeries. However, the guidelines do not specify risk factors for which prophylaxis is indicated, nor do they address the length of treatment.

Source: Hetsroni I, Lyman S, Do H, et al. Symptomatic pulmonary embolism after outpatient arthroscopic procedures of the knee: The incidence and risk factors in 418,323 arthroscopies. J Bone Joint Surg (Br). 2011;93-B:47-51.