Incidence of Venous Thromboembolism in Patients with Cushing's Syndrome: A Multicenter Cohort Study

Venous thrombosis has frequently been reported in patients with endogenous Cushing's syndrome (CS).The aim of this study was to evaluate the incidence of venous thromboembolism (VTE) in patients with CS prior to treatment and after surgery.We conducted a multicenter cohort study at all university medical centers in The Netherlands.Consecutive patients diagnosed with endogenous CS of benign origin between January 1990 and June 2010 were eligible for inclusion. Patients surgically treated for nonfunctioning pituitary adenoma served as controls for the incidence of postoperative VTE in ACTH-dependent CS.We documented all objectively confirmed VTE during 3 yr prior to, and 3 yr after treatment onset. The incidences of VTE were expressed as incidence rates.A total of 473 patients (mean age 42 yr, 363 women) were included (360 ACTH-dependent pituitary CS). The total number of person-years was 2526. Thirty-seven patients experienced VTE during the study period, resulting in an incidence rate of 14.6 [95% confidence interval (CI) 10.3-20.1] per 1000 person-years. The incidence rate for first-ever VTE prior to treatment was 12.9 (95% CI 7.5-12.6) per 1000 person-years (17 events). The risk of postoperative VTE, defined as risk within 3 months after surgery, was 0% for ACTH-independent and 3.4% (95% CI 2.0-5.9) for ACTH-dependent CS (12 events in 350 patients); most events occurred between 1 wk and 2 months after surgery. Compared with the controls, the risk of postoperative VTE in patients undergoing transsphenoidal surgery was significantly greater (P = 0.01).Patients with CS are at high risk of VTE, especially during active disease and after pituitary surgery. Guidelines on thromboprophylaxis are urgently needed.