A study reviewing a large claims database adds the use of combined oral contraceptive pills (COCPs) to the list of risk factors for deep vein thrombosis (DVT) or pulmonary embolism (PE) after knee arthroscopy or anterior cruciate ligament reconstruction (ACLR). Lead author Sophia Traven, MD, from the department of orthopaedics at the Medical University of South Carolina in Charleston, will present the study results today.

“Knee arthroscopy is the most commonly performed orthopaedic procedure worldwide and is generally regarded as safe, with an exceptionally low complication rate,” Dr. Traven and coauthors wrote. Although the use of COCPs is associated with an elevated risk of venous thromboembolism (VTE) following orthopaedic procedures, they added, the magnitude of VTE risk is not well delineated.

To better characterize that risk, the researchers reviewed data from a large healthcare database to identify all women aged between 16 and 40 years who underwent simple knee arthroscopy and ACL reconstruction between 2010 and 2015. Patients were stratified by whether they had a documented pharmaceutical claim for COCP therapy in the 12 months preceding surgery. The primary outcome of interest was incidence of DVT or PE within 90 days of the index procedure.

In total, 64,165 patients were included in the analysis. Patients were divided into two cohorts: women receiving preoperative COCP therapy (defined as a documented pharmaceutical claim for COCP therapy in the 12 months preceding surgery; n = 16,304) and women not receiving COCP therapy (n = 47,861).

Patients on COCPs were younger, with a median age of 23 years, compared to 30 years in the no-COCPs group. In addition, patients on COCPs tended to have a lower preoperative comorbidity burden, including lower rates of obesity, hyperlipidemia, active tobacco use, hypertension, coronary artery disease, and diabetes (P <0.001). there was no difference between cohorts in terms of renal disease, congestive heart failure, rheumatoid disease, alcohol use disorder, or depression (>P >0.05). No deaths were reported in either cohort.

The overall incidence of VTE was low, at 1.2 percent. However, patients taking COCPs had more than double the risk of VTE (1.78 percent versus 1.00 percent), with an odds ratio (OR) of 2.1 (P <0.001). specifically, in a multivariate analysis, the ors for dvt and pe were 2.21 and 1.74, respectively, among patients on cocps. when looking at patients with or without concomitant acl reconstruction and knee arthroscopy, the researchers found that there was no increased risk of pe in those undergoing aclr (0.23 percent versus 0.18 percent;>P = 0.342).

Patients who experienced VTE tended to be younger than those who did not experience VTE (median ages, 32 years versus 28 years; P <0.001). other patient characteristics associated with vte were obesity, hypertension, and diabetes. in a subgroup analysis of patients with multiple risk factors, active tobacco use alone was not associated with increased vte risk, but smoking and obesity appeared to demonstrate a synergistic effect when combined with cocp use. “specifically, 3.1 percent of obese patients on cocps (or, 3.1) and 4.0 percent of smokers on cocps (or, 4.3) developed a postoperative vte,” they wrote.>

Dr. Traven and coauthors noted several important limitations of this study, including the study’s retrospective nature and the selection bias inherent to the claims database used in the analysis. Nonetheless, their results suggest that patients on perioperative COCPs who are undergoing simple knee arthroscopy or ACLR should be counseled regarding an increased risk of VTE. “Patients may benefit from either stopping their COCPs one month prior to surgery or consider postoperative anticoagulation when perioperative COCP use and/or other risk factors are identified,” the authors concluded.

The study will be presented as Paper 695 at 12:10 p.m. in Ballroom 6E.

Dr. Traven’s coauthors on “Oral Contraceptive Pills Double the Risk for Venous Thromboembolism after Knee Arthroscopy and Anterior Cruciate Ligament Reconstruction” are Kevin Xavier Farley, MD, MS; Michael Brandon Gottschalk, MD; Brett Goodloe, MD; Shane Kelby Woolf, MD; John W. Xerogeanes, MD; and Harris Slone, MD.

Ariel DeMaio is the managing editor of AAOS Now.