SAME-DAY SAFETY The importance of considering patient-specific prophylaxis measures is heightened as more complex procedures move to the outpatient setting.

It's not easy to tell which patients are at risk for developing life-threatening deep vein thrombosis (DVT) and pulmonary embolus (PE), known collectively as venous thromboembolism (VTE). Besides the fact that clotting risk factors aren't obvious, every patient has different risks for developing VTE, regardless of the type of surgery they're undergoing.

My go-to standard to gauge VTE risk is the Caprini Score Risk Assessment Model. The tool, which assesses the risk stratification of individual patients, takes into account not only the type and extent of the scheduled surgery, but also the patient's medical comorbidities, personal and family history of clots, and other recognized factors that help you identify clotting risk. The Caprini score guides you to ask the questions that can reveal a patient's true risk of VTE. The exhaustive list of questions lets providers create an aggregate risk factor score, which will help determine the preventative measures that would work best on a case-by-case basis.

High Caprini scores should prompt you to further assess patients to see how to modify and reduce their risk factors. Once you've identified risk factors, you need to stop, slow down and ask yourself if any of them are modifiable. For example:

• Has a patient had a recent operation? Maybe you can wait longer than 30 days to perform an elective procedure to ensure risk from a prior anesthetic has resolved.
• Does a cancer patient have a port inserted for the infusion of chemotherapy? Try to remove the port in advance of surgery to eliminate it as a potential thrombotic source.
• Are young female patients on oral contraceptives, which are known to be associated with clots? Have them stop taking the pills 4 weeks before surgery, so the medications are metabolized long before they enter your ORs.

Clearly, consideration of VTE risk level at a pre-op visit, as opposed to in the pre-op holding area, may allow modification of identified risk factors.

Caprini Score >> the higher the number, the greater the risk of VTE

PRIME NUMBER The Caprini score offers guidance for applying preventative measures on a case-by-case basis.

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Add 1 point for each statement that applies now or within the past month

• Age 41 to 60 years
• Swollen legs
• Varicose veins
• BMI >25
• Minor surgery (less than 45 minutes) planned
• Sepsis
• Serious lung disease
• Use of oral contraceptives or hormone replacement therapy
• Pregnancy or postpartum
• History of unexplained stillborn child, 3 or more recurrent spontaneous abortions, premature birth with toxemia or growth-restricted infant
• Acute myocardial infarction
• Congestive heart failure
• Medical patients currently at bed rest
• History of inflammatory bowel disease
• History of major surgery
• Abnormal pulmonary function (COPD)

Add 2 points for each statement that applies

• Age 61 to 74 years
• Arthroscopic surgery
• Malignancy (present or previous)
• Laparoscopic surgery expected to last longer than 45 minutes
• Patient confined to bed for longer than 72 hours
• Immobilizing plaster cast for less than 1 month
• Central venous access
• Major surgery expected to last longer than 45 minutes

Add 3 points for each statement that applies

• Age 75 years or older
• History of DVT/PE
• Positive factor V leiden (mutation of blood clotting factor)
• Elevated serum homocysteine
• Heparin-induced thrombocytopenia (HIT)
  (Do not use heparin or any low-molecular weight heparin)
• Elevated anticardiolipin antibodies
• Family history of thrombosis*
  * The most frequently missed risk factor
• Positive prothrombin 20210A
• Positive lupus anticoagulant
• Other congenital or acquired thrombophilia If yes, type: ____________________________

Add 5 points for each statement that applies now or within the past month

• History of stroke
• Elective major lower extremity arthroplasty
• Hip, pelvis or leg fracture
• Acute spinal cord injury
• Multiple trauma

Preventative measures
For patients who are still at risk when they present for surgery, consider implementing some or all of the following proven VTE prevention measures:

• Anesthesia adjustment. Some modalities are more favorable to clot-risk reduction. For example, performing extremity surgeries under regional or spinal anesthesia has been shown to reduce the risk of clots, as compared with general anesthesia.
• Leg compression. Graduated compression stockings and sequential compression devices are proven ways to decrease risk of clotting in a non-invasive way. After outpatient procedures, you expect patients will be up and moving, but sequential compression devices should be used during surgery to minimize risk.
• Chemical prophylaxis. Outpatients don't benefit uniformly from chemical prophylaxis, so before administering medications to prevent clotting, consider a patient's specific VTE risk. It's not unreasonable to send patients with a very high risk for clotting home on chemical prophylaxis, but that's a clinical decision that needs to be made on a case-by-case basis, as no data-driven guideline exists.

The effectiveness and safety profiles of both subcutaneous unfractionated heparin and enoxaparin sodium has been extensively studied over the past 20 to 30 years; these injectable medications are the most reliable, but may be uncomfortable for patients. Researchers are studying the prophylaxis potential of several novel oral anticoagulants (NOACs), which have been shown in some studies to have a favorable safety profile in inpatients. NOACs do not require monitoring and are oral, as opposed to injected. Their effectiveness and safety profile specific to VTE prophylaxis is still being defined, and published data specific to the ambulatory patient population is limited, at best. Currently, in my opinion, unfractionated heparin or enoxaparin is the best choice based on a predictable effectiveness and safety profile.

Precision medicine
Three-fourths of surgical patients might be receiving anti-clotting medications they don't need, according to research my colleagues and I recently published in the Annals of Surgery (osmag.net/UFjyF3). The meta-analysis found that chemical prophylaxis is beneficial only for patients with Caprini scores of 7 or higher. Conversely, the risk-benefit relationship of chemoprophylaxis for patients with Caprini scores of 6 or lower was either unclear or unfavorable. While these findings were largely based on data from inpatient surgical patients, the results are certainly relevant to ambulatory surgery. The findings suggest a one-size-fits-all approach to anticoagulant therapy for VTE prophylaxis results in a substantial number of patients being over-treated.

There was a significant variability in VTE risk among the patients, which reinforces the importance of considering a patient's risk based on their individual factors. It's safer to adopt a precision medicine approach, where the intervention is guided by the risk-benefit relationship at the patient level and based on the patient's Caprini score. Using individualized risk stratification is the surest way to identify patients at high risk for developing post-op clots who would benefit most from preventative measures. OSM