Symptomatic venous thromboembolism following fractures distal to the knee: a nationwide Danish cohort study.

Background: Our aims were to determine the incidence of symptomatic deep venous thrombosis (DVT) and pulmonary embolism (PE) that required inpatient or outpatient treatment, and to identify specific risk factors associated with DVT/PE in patients who had undergone surgery for a fracture distal to the knee. Methods: Using individual linkage of nationwide registries, we included all Danish patients who had undergone surgery for a fracture distal to the knee between 1999 and 2011. Patients were followed for 180 days from discharge. Event rates of DVT/PE were calculated, and significant risk factors were identified with use of multivariable Cox regression analyses. Routine postdischarge antithrombotic chemoprophylaxis was not given to these patients. Results: The study included 57,619 patients, 594 of whom had a venous thromboembolic event during the follow-up period. Thirty-nine (6.6%) of the 594 events were death due to PE. The overall event rate during the 180-day study period was 1.0%. The incidence rate was 7.28 events per 100 person-years before discharge, decreasing to a stable level below one event per 100 person-years in week 13 to 14 after discharge. Use of oral contraception by patients eighteen to fifty years of age (hazard ratio [HR] = 5.23, 95% confidence level [CI] = 3.35 to 8.18), previous DVT (HR = 6.27, 95% CI = 4.18 to 9.40), previous PE (HR = 5.45, 95% CI = 3.05 to 9.74), coagulopathy (HR = 2.47, 95% CI = 1.07 to 5.72), and peripheral artery disease (HR = 2.34, 95% CI = 1.20 to 4.56) were the factors associated with the highest risk of postoperative DVT/PE. Also, increasing age, increasing body mass index, cancer, and treatment with nonsteroidal anti-inflammatory drugs were associated with a significantly increased risk of DVT/PE. Conclusions: The incidence of DVT/PE was low following surgery for fractures distal to the knee; however, the risk was increased in the presence of a number of risk factors. This study suggests that specific groups of patients undergoing surgery for a fracture distal to the knee might benefit from postdischarge antithrombotic treatment.