Higher Pulmonary Embolism Risk in Morbidly Obese Patients on Aspirin Monotherapy after Total Knee Arthroplasty: A Claims Database Analysis.

BACKGROUND

Aspirin is the most common drug used for venous thromboembolism (VTE) prophylaxis after total knee arthroplasty (TKA). Morbid obesity is a potential risk factor for VTE, prompting some to use stronger anticoagulants. However, there are no established guidelines for VTE prevention in obese or morbidly obese patients undergoing primary TKA.

METHODS

Using a national administrative claims database, patients who underwent primary TKA were divided into the following three cohorts based on body mass index (BMI): < 30, 30 to 39.9, or ≥ 40. Each patient had a prescription claim for aspirin, but no other prophylaxis agents within 3 days after the index procedure. We assessed deep vein thrombosis (DVT) and pulmonary embolism (PE) incidence at 90 and 180 days postoperatively. Secondary outcomes included wound dehiscence; hematoma; periprosthetic joint infection; and debridement, antibiotics, and implant retention or explantation procedures. We included 20,097 patients, of whom 4,277 (21%), 10,663 (53%), and 5,157 (26%) had a BMI < 30, 30 to 39.9, and ≥ 40, respectively.

RESULTS

In the multivariable analysis, there was no difference in the incidence of DVT or PE within 90 or 180 days after surgery for the BMI 30 to 39.9 compared to the BMI < 30 cohort. However, the incidence of PE within 90 days after surgery was higher in the BMI ≥ 40 cohort (odds ratio: 2.74), an effect that disappeared by 180 days. There was a higher adjusted odds of debridement, antibiotics, and implant retention procedures in the BMI ≥ 40 compared to the BMI < 30 cohort; otherwise, the incidence of secondary outcomes did not differ by BMI.

CONCLUSIONS

When aspirin was used as a standardized monotherapy for VTE prophylaxis following primary TKA, there was an increased 90-day incidence of PE in morbidly obese patients but no difference in DVT or PE incidence in obese patients.