Occurrence and predictors of recurrence after a first episode of acute venous thromboembolism: population-based Worcester Venous Thromboembolism Study.

Venous thromboembolism (VTE) has multiple risk factors and tends to recur. Despite the benefits of anticoagulation, the prevalence of, and case-fatality rate associated with, recurrent VTE remains a concern after an acute episode; it is particularly high during the acute treatment phase. We sought to quantify the magnitude, identify predictors, and develop risk score calculator of recurrence within 3 years after first-time VTE. This was a population-based surveillance study among residents of central Massachusetts (MA), USA, diagnosed with an acute first-time pulmonary embolism and/or lower-extremity deep vein thrombosis from 1999 to 2009 in hospital and ambulatory settings in all 12 central MA hospitals. Medical records were reviewed and validated. The 2989 study patients were followed for 5836 person-years [mean follow-up 23.4 (median 30) months]. Mean age was 64.3 years, 44 % were men, and 94 % were white. The cumulative incidence rate of recurrent VTE within 3 years after an index VTE was 15 % overall, and 25, 13, and 13 % among patients with active cancer, provoked, or unprovoked VTE, respectively. Multivariable regression indicated that active cancer, varicose vein stripping, and inferior vena cava filter placement were independent predictors of recurrence during both 3-month and 3-year follow-up. A risk score calculator was developed based on the 3-month prognostic model. In conclusion, the rate of VTE recurrence over 3 years of follow-up remained high. The risk score calculator may assist clinicians at the index encounter in determining the frequency of clinical surveillance and appropriate outpatient treatment of VTE during the acute treatment phase.