Incidence of venous thromboembolism and bleeding events in patients with lower extremity orthopedic surgery: a retrospective analysis of a Japanese healthcare database

Background: Orthopedic surgeries of lower extremities such as total knee arthroplasty (TKA), total hip arthroplasty (THA), and hip fracture surgery (HFS) are widely considered to carry a high risk of developing deep venous thrombosis (DVT) and pulmonary thromboembolism (PTE). Growing attention to epidemiological studies using a healthcare database led us to quantify the risks using a Japanese database to reveal recent medical care for such events. Methods: The study comprised 36,947 patients who had undergone orthopedic surgeries of the lower extremities and whose medical information from April 2008 to September 2013 was available. The source population of the database was derived from 100 acute-care hospitals with Diagnosis Procedure Combination. The events were defined by diagnosis, medication, imaging, and laboratory tests. Results: A breakdown of patients who underwent orthopedic surgeries by type of surgery showed 13.6% for TKA, 10.4% for THA, 56.8% for HFS, 1.5% for rupture of Achilles tendon, and 18.0% for simple fracture of lower extremities. The incidence for DVT, PTE, and bleeding events by type of surgery was 1.3, 0.2, and 1.0% for TKA; 0.9, 0.2, and 1. 1% for THA; and 0.4, 0.1, and 1.8% for HFS, respectively. The population for risk factor analysis consisted of patients with similar background factors who underwent TKA, THA, or HFS. The statistically significant risk factors for PTE analyzed by the backward elimination procedure in a multivariate model were female sex, history of venous thromboembolism (VTE), thrombophilia, and varicose veins of lower extremity. Conclusions: The incidence of DVT, PTE, and bleeding events and the risk factors for DVT and PTE in patients by type of orthopedic surgeries of lower extremities found in our study are considered to be rational as they reflect evidence from real-world cases.