Findings challenge current surgical prophylaxis strategies, researchers suggest
Risk of recurrent venous thromboembolism (VTE) following surgery in people with a history of VTE is high, with cancer surgeries, major orthopedic surgeries, and gastrointestinal and heart and lung procedures associated with the highest increase in risk.
The overall risk of developing a VTE within 6 months after surgery was 4.6% (range 2.3%-9.3%) in a longitudinal, follow-up cohort study involving nearly 4,000 patients in the Netherlands who had previous VTEs.
The study, published online in JAMA Network Open, is among the first to describe the absolute risk of VTE recurrence following surgery in this high-risk population, and the findings have implications for the surgical management of patients with previous VTEs, said the study's lead researcher, Banne Nemeth, MD, of Leiden University Medical Center in the Netherlands.
Nemeth told MedPage Today that low, subtherapeutic doses of thrombolytic agents typically given for prophylaxis in surgical patients may not be adequate to protect these high-risk patients from recurrent thromboembolism.
"Given that the risk is very high, we might need to step up our thromboprophylaxis," he said. "Patients may be better off with more prophylaxis -- maybe a double dose or even a therapeutic dose."
But Nemeth was quick to add that given the bleeding risk associated with thromboprophylaxis, randomized clinical trials will be needed to examine the risks and benefits of this approach "before we think of changing clinical practice."
The follow-up study included patients with a VTE history who participated in the Multiple Environment and Genetic Assessment (MEGA) follow-up study, with data collected from the spring of 1999 until April 2010. Participants were recruited from six anticoagulation clinics in the Netherlands.
Nemeth and colleagues analyzed data on 3,741 individuals with previous VTEs, of whom 580 underwent surgery during follow-up. Overall, 578 major operations and 230 minor operations were performed; 275 were orthopedic and 533 were non-orthopedic.
Mean age was 48.4, and just over half of participants were women. Median follow-up was 5.7 years (IQR 3.0-7.2). Recurrent VTE occurred in 601 participants.
Among patients who had a surgical procedure performed during follow-up, cumulative totals of recurrent VTE were 13 within 1 month, 21 within 2 months, 30 within 6 months, and 38 within 12 months of surgery.
Expressed as percentages, "[t]he cumulative incidence of recurrent VTE at 1 month was 2.1% (95% CI 1.2%-3.6%), which increased to 3.3% (95% CI 2.1%-5.1%) at 3 months, 4.6% (95% CI 3.1%-6.6%) at 6 months, and 6.3% (95% CI 4.6%-8.7%) at 1 year," the researchers wrote.
In patients with a VTE history who did not have surgery during the follow-up period, the 3-month risk of recurrent VTE was 0.8% (95% CI 0.6%-1.1%).
Among surgery patients, the risk of recurrence was highest during the first month following surgery (HR 6.8, 95% CI 3.9-11.9, vs non-surgical patients) and remained elevated through the 6-month mark (HR 1.7, 95% CI 0.8-3.7).
"Vascular and outpatient surgical procedures were associated with the lowest recurrence risk at 6 months (vascular: HR 2.3, 95% CI 0.6-8.8; outpatient: HR 3.1, 95% CI 1.4-6.7)," the researchers wrote. "Patients who had undergone gastrointestinal procedures (e.g., esophagus, stomach, bowel, or rectal operations) had a high risk of recurrent VTE at 6 months (HR 8.4, 95% CI 4.0-17.8)."
Major surgery was associated with a higher VTE recurrence risk than having minor surgery.
Study strengths cited by the researchers included the large study cohort, long follow-up, and the objective classification of surgical procedures.
Limitations included a lack of information on thromboprophylaxis therapy following surgery, and possible inadequate adjustment (only sex and age were adjusted for) in the Cox regression analysis.
"Our results stress the need for a revision of the thromboprophylactic approach following surgery in patients with a history of VTE, the duration and dosage of which may need to be intensified and individualized," the researchers concluded.
Nemeth and co-authors reported having no relevant relationships with industry related to the study.
JAMA Network Open
Source Reference: Nemeth B, et al "Risk and risk factors associated with recurrent venous thromboembolism following surgery in patients with history of venous thromboembolism" JAMA Network Open 2019; 2(5): e193690.
Read the original article on Medpage Today: VTE Recurrence Risk Quantified in Surgery Patients