MONTREAL—Although guidelines have been published by the American College of Chest Physicians (ACCP) for the administration of thromboprophylaxis to patients undergoing surgery, a new study suggests that physicians may not always follow them.[1] And what is worse, even when these guidelines are fully heeded, they may not deal adequately with venous thromboembolism (VTE). As a result, preventable cases of VTE occur in many types of patients—not only those who undergo orthopedic and, especially, general surgery, but also medical patients, such as those with pneumonia or stroke.

Donald M. Arnold, MD, and colleagues from Sir Mortimer B. Davis Jewish General Hospital in Montreal performed a historical cohort study to identify possible deficiencies in physicians’ practice of VTE prevention. They evaluated 253 cases of VTE that developed in 245 patients from 1996 to 1997 in a large teaching hospital. Although thromboprophylaxis had been indicated in 65 (25.7%) of these cases, it was not administered in 44, for one or more reasons. The authors classified these as preventable cases of VTE.

In most of the preventable cases, the indicated antithrombotic therapy was either omitted (21 patients) or administered for too short a period (10 patients). In nine cases, a type of prophylaxis other than that recommended by ACCP guidelines was provided. Dosing was too infrequent in six cases, and it was delayed by more than 24 hours in three.

In another three cases, anticoagulants were administered but in lesser quantities than those that the guidelines recommend. For example, two of these patients had been given appropriate warfarin doses, but the international normalized ratio did not reach therapeutic levels until seven days after surgery.

Twenty-one (8.3%) of the 253 VTE cases were classified as non-preventable because they occurred despite proper thromboprophylaxis; in another nine cases (3.6%), the patients were ineligible for thromboprophylaxis. The remaining 179 cases (70.8%) were considered spontaneous.

Therefore, Dr. Arnold and colleagues calculated that appropriate preventive measures had not been administered in two thirds of the VTE cases in which thromboprophylaxis had been indicated.

WHAT WENT WRONG?

Omissions of, or inadequacies in, thromboprophylaxis most often occurred in patients who had undergone general surgery or neurosurgery; in comparison, only a few cases of preventable VTE developed in patients undergoing orthopedic surgery. However, nine of the cases of preventable VTE occurred in patients with pneumonia and stroke, indicating a need for vigilance in these settings.

The researchers speculate that the most common problem with prophylaxis administration, complete treatment omission, could have had a variety of causes. Perhaps some physicians were unaware of ACCP recommendations for thromboprophylaxis, or they may have been reluctant to administer it because of the bleeding risk it seemed to present.

In an interview with PULMONARY REVIEWS, Dr. Arnold stated that “human nature would dictate that causing harm (ie, bleeding) is much more difficult to contend with emotionally than not preventing harm (ie, VTE); as such, in high-risk surgical procedures, I can understand physicians’ reluctance to administer anticoagulants despite the evidence that it is safe.” Nevertheless, he added that “by and large, the benefits of VTE prophylaxis outweigh the risks of bleeding.”

ARE GUIDELINES INSUFFICIENT?

In cases in which VTE was considered non-preventable, the researchers suggest that ACCP guidelines might be inadequate to deal with some distal forms of VTE. They speculate that developmment of VTE despite adherence to guidelines indicates a need to improve existing protocols and that further research should be aimed at understanding how physicians could be helped to keep thromboprophylaxis in mind.

—Owen McCarthy

Reference
1. Arnold DM, Kahn SR, Shrier I. Missed opportunities for prevention of venous thromboembolism: an evaluation of the use of thromboprophylaxis guidelines. Chest. 2001;120:1964-1971.

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