A Higher Altitude Is an Independent Risk Factor for Venous Thromboembolisms After Total Hip Arthroplasty.

BACKGROUND: High altitudes lead to physiological changes that may predispose to venous thromboembolisms (VTEs) including deep vein thrombosis and pulmonary embolism (PE). No prior study has evaluated if there is also a higher risk of VTEs for total hip arthroplasties (THAs) performed at higher elevations. The purpose of this retrospective study was to identify if undergoing THA at a higher altitude center (>4000 feet above sea level) is an independent risk factor for a postoperative VTE. METHODS: A thorough evaluation of the Pearl Diver Database was performed for patients undergoing THAs from 2005 to 2014. Using International Classification of Diseases Ninth Edition facilitated in ascertaining patients who underwent THA. Using the ZIP codes of the hospitals where the procedure occurred, we separated our groups into high-altitude (>4000 ft) and low-altitude (<100 ft) groups. RESULTS: In the first 30 postoperative days, patients undergoing THA at a higher altitude experienced a significantly higher rate of PEs (odds ratio, 1.74; P = .003) when compared to similar patients at lower altitudes. This trend was also present for PE (odds ratio, 1.59; P < .001) at 90 days postoperatively. CONCLUSION: THAs performed at higher altitudes (>4000 feet) have a higher rate of acute postoperative PEs in the first 30 days and also 90 days postoperatively when compared to matched patients receiving the same surgery at a lower altitude (<100 feet). THA patients at high altitude should be counseled on these increased risks; however, owing to retrospective nature and confounders, prospective studies are necessary to explore this outcome in more detail.