A higher altitude is an independent risk factor for venous thromboembolisms following total shoulder arthroplasty

Abstract

Introduction: High altitudes lead to physiological changes that may predispose to venous thromboembolisms (VTE) including deep vein thrombosis (DVT) and pulmonary embolism (PE). No prior study has evaluated if there is also a higher risk of VTEs after total shoulder arthroplasties (TSAs) performed at higher elevations compared to lower elevations. The purpose of this study was to identify if undergoing TSA at a higher altitude center (> 4000 feet above sea level) is an independent risk factor for a postoperative VTE. Methods: A retrospective review was performed from 2005 to 2014 using the Medicare Standard Analytical Files of the Pearl Diver database (Pearl Diver Technologies, West Conshohocken, PA, USA). The inclusion criteria for the study group consisted of all patients in the database undergoing primary TSAs at an altitude above 4000 feet. Patients were queried using the International Classification of Disease 9th revision codes (ICD-9). All patients undergoing primary TSA were queried using ICD-9 procedure code 81.80. Patients were filtered using the zip codes of the hospitals where the procedure occurred and were separated into high (> 4,000 ft) and low (< 100 ft) altitudes. Patients undergoing TSA in altitudes < 100 ft represented the control group. Patients with a history of VTE, DVT, PE, and coagulation disorders were excluded from the study. Patients in the study group were randomly matched 1:1 according to age, gender, and comorbidities. Two mutually exclusive cohorts were formed and rates of VTE, DVT, and PE were analyzed and compared. Statistical analysis was performed using the programming language R (University of Auckland, New Zealand). An alpha value less than 0.05 was considered statistically significant. Results: In the first 30 postoperative days, patients undergoing TSA at a higher altitude experienced a significantly higher rate of PEs (odds ratio [OR], 39.5; P = < 0.001) when compared to similar patients at lower altitudes. This trend was also present for PE (OR, 2.02; P < 0.03) at 90 days postoperatively. Conclusion: TSAs performed at higher altitudes (> 4000 feet) have a higher rate of acute postoperative PEs in the first 30 days and 90 days postoperatively when compared to matched patients receiving the same surgery at a lower altitude (< 100 feet). TSA patients at high altitude should be counseled on these increased risks.

Risk factors for venous thromboembolism in total shoulder arthroplasty

“…Although we analyzed patient demographic characteristics, comorbidities, and complications associated with VTE, many risk factors found in prior studies were not found to be risk factors for VTE in our study. For example, inpatient status, sex, anesthesia type, obesity, smoking, malignancy, operative time, CHF, COPD, anemia, and independent functional status were not associated with VTE occurrence as loosely suggested in previous literature 12, 14, 15, 33, 36, 38. However, even in recent studies, these risk factors and pre-existing conditions have not been replicated, with statistical significance often not having been met 21, 40.…”

“…Previous studies have suggested that patients with comorbidities including prior VTE, advanced age, critical care hospitalization, diabetes, heart disease, malignancy, lung disease, renal disease, obesity, pregnancy, and blood disorders are thought to have an increased risk of VTE 12, 15, 33. In addition, modifiable factors such as mobility, smoking, prolonged operative time, patient positioning, intramedullary instrumentation, and alcohol use have been implicated in the increased risk of VTE in TSA patients 12, 14, 33, 42.…”

“…Previous studies have suggested that patients with comorbidities including prior VTE, advanced age, critical care hospitalization, diabetes, heart disease, malignancy, lung disease, renal disease, obesity, pregnancy, and blood disorders are thought to have an increased risk of VTE 12, 15, 33. In addition, modifiable factors such as mobility, smoking, prolonged operative time, patient positioning, intramedullary instrumentation, and alcohol use have been implicated in the increased risk of VTE in TSA patients 12, 14, 33, 42. However, these preoperative factors are not consistently associated with an increased risk of VTE in the literature, as numerous studies have failed to show notable associations between VTE and malignancy, increasing age, prior VTE, reduced mobility, blood disorders, and obesity 14, 21, 38, 40.…”

High Altitude Is an Independent Risk Factor for Developing a Pulmonary Embolism, but Not a Deep Vein Thrombosis Following a 1- to 2-Level Lumbar Fusion

“…While this may under report actual VTE rates, theoretically these errors would occur at equal rates in both cohorts studied. It is also possible that our elevation parameters, which we based on prior non-spinerelated studies, 7,8,27 may not adequately identify if altitude was a risk factor for this cohort and other elevations would instead show a risk. Additionally, there is an inability to screen patients preoperatively based on our methods, and so preexisting DVTs or PEs may not have been excluded.…”

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

“…Within the field of orthopaedic surgery, several studies have found an increased incidence rate of VTEs with higher altitude following arthroscopic knee surgery as well as total joint replacements. 11,12 However, there is minimal data investigating the effect that altitude plays on the development of VTEs in pelvic ring and acetabular fractures.…”