Effect of a near-universal hospitalization-based prophylaxis regimen on annual number of venous thromboembolism events in the US

The annual number of US venous thromboembolism (VTE) events, the number of potentially preventable events, and the effect of hospitalization-based prophylaxis are uncertain. We estimated VTE attack (incident plus recurrent VTE) rates and the total annual number of US VTE events related and unrelated to hospitalization using Rochester Epidemiology Project resources to identify all Olmsted County, Minnesota, residents with incident or recurrent VTE over the 6-year period 2005-2010. The average annual VTE attack rates related and unrelated to hospitalization were 282 and 8 per 10 000 person-years, respectively. The estimated average number of US VTE events was 495 669 per year (48% unrelated to hospitalization). Among Olmsted County residents hospitalized at a Mayo Clinic hospital from 2005 to 2010, the proportion of patients receiving VTE prophylaxis or with an indication that prophylaxis was unnecessary increased from ∼40% in 2005 to ∼90% by 2010. The annual age- and sex-adjusted hospitalization-related (in-hospital) VTE attack rates from 2005 to 2010 ranged from 251 to 306 (1155 to 1751) per 10 000 person-years (bed-years) and did not change significantly. The median durations of hospitalization and in-hospital prophylaxis were 3 days and 70 hours, respectively. A total of 75% of VTE events occurred after hospital discharge, with a 19.5-day median time to VTE. Additional efforts are needed to identify the individual inpatient and outpatient at high risk for incident and recurrent VTE and target (longer duration) primary and secondary prophylaxis to high-risk individuals who would benefit most.