Higher altitude leads to increased risk of venous thromboembolism after acetabular and pelvic ring injury

Abstract

Introduction: There is a high post-operative incidence of venous thromboembolisms (VTEs), specifically deep vein thrombosis (DVT) and pulmonary embolism (PE), in pelvic ring and acetabular fractures, and identification of risk factors for VTEs is crucial to decrease this highly morbid complication. High altitudes have a known physiological effect on the body that may predispose patients to developing VTEs in the postoperative period. The purpose of this study was to investigate the relationship between pelvic ring and acetabular fractures occurring at high altitudes and the development of postoperative VTEs. Methods: In this retrospective study, the Truven MarketScan claims database was used to identify patients who underwent surgical fixation of a pelvic ring and/or acetabular fracture from January 2009 to December 2018 using Current Procedural Terminology (CPT) codes. Patient characteristics, including medical comorbidities, were collected. The zip codes of where the surgeries took place were used to determine recovery altitude and patients were separated into either the high altitude (>4000 feet) or low altitude (<100 feet) cohorts. Chi-squared and multivariate analyses were performed to investigate the association between altitude and the development of VTE postoperatively. Results: In total, 68,923 patients were included for analysis. At 30-days postoperatively, a higher altitude was associated with increased odds of developing a PE (OR 1.47, p ¼ 0.019). At 90-days postoperatively, a higher altitude was associated with increased odds of DVT (OR 1.24, p ¼ 0.029) and PE (OR 1.63, p < 0.001). Conclusion: Surgical fixation of pelvic ring and acetabular fractures performed at a higher altitude (>4,000feet) are associated with increased odds of developing a PE in the first 30 days as well as developing a DVT or PE at 90 days postoperatively. Future prospective studies are needed to further elucidate the causality of altitude on the development of postoperative VTEs.

High Altitude as a Risk Factor for Venous Thromboembolism in Tibial Plateau Fractures

“…It is well known that high altitudes induce physiological changes for adaption to a relatively lower oxygen tension environment. Previous literature has shown that these changes may predispose to thrombogenesis by way of hypercoagulability and venous stasis [ 2 , 15 , 16 ]. As the oxygen tension lowers at higher altitudes there is a compensatory increased red blood cell and resulting hemoconcentration [ 2 , 17 ].…”

“…These records allow for the analysis of multiple parameters, including procedure data, location, medical comorbidities, medical prescriptions, and post-operative follow-up care. Prior orthopedic studies have used this database for clinical investigation and it is well-published in the literature [ 2 ].…”

“…Our exclusion criteria included: open fracture(s), patients currently prescribed oral contraceptives, patients who were not continuously enrolled in the database for six months prior to or after surgery, prior history of VTE, hypercoagulable medical condition (defined as having an International Classification of Diseases (ICD) code for Factor V Leiden, antiphospholipid antibody syndrome and/or Protein C and S deficiency), and less than 18 years of age at the time of surgery. In line with previous studies, we expanded our query to six months to ensure adequate follow-up and to exclude patients who might have a predisposition to developing a VTE [ 2 ]. Additionally, because tibial plateau fractures commonly occur in the polytraumatic patient, we attempted to control for, and exclude, patients with co-existing injuries to reduce potential confounders.…”

“…A commercially available zip code database (Datasheer, L.L.C., Hope Junction, New York) was then used to determine each patient’s altitude at the time of surgery. In line with previous literature, altitude was divided into two cohorts: high-altitude (4,000 feet or greater) or low-altitude (100 feet or less) with the assumption that a patient’s post-operative course occurred at the same altitude as their original operation [ 2 , 20 ].…”

“…Multiple studies have been published on risk factors that increase a trauma patient’s risk for VTE events [ 3 , 5 , 14 ]. However, despite higher altitudes having been shown to lead to adaptive changes that favor a prothrombotic environment, there are few publications evaluating its association in orthopedic trauma populations [ 2 , 15 , 16 ]. Interestingly, arthroscopy, arthroplasty, and spine fusion literature show higher rates of symptomatic VTE in patients undergoing surgery at higher elevations when compared to lower elevations [ 17 - 21 ].…”