Influence of the duration of hospital length of stay on frequency of prophylaxis and risk for venous thromboembolism among patients hospitalized for acute medical illnesses in the USA.

Background: We evaluated whether the duration of hospital stay influences venous thromboembolism (VTE) prophylaxis patterns and VTE risk during hospitalization and post-discharge among patients hospitalized for acute illnesses in the USA.

Methods: Patients hospitalized for acute illnesses were identified from the US MarketScan Commercial and Medicare databases (January 1, 2012-June 30, 2015). Patients were stratified by index hospital length of stay (LOS), with study groups with 1-3 day, 4-6 day, and ≥7 day LOSs. Use of VTE prophylaxis and VTE event rates during and after hospitalization (6-month follow-up) were evaluated.

Results: Of the overall population, 8647 had a 1-3 day LOS, 5551 had a 4-6 day LOS, and 3697 had a ≥7 day LOS. A greater proportion of patients with a 1-3 day LOS (66.2%) did not receive any VTE prophylaxis in comparison to patients with a 4-6 day LOS (55.0%) and ≥7 day LOS (48.8%; p <0.001). Proportions of patients with VTE events during the index hospitalization increased with longer hospital LOS (1-3 day LOS: 0.5%; 4-6 day LOS: 1.3%; ≥7 day LOS: 5.4%), as did proportions of patients with VTE events during the 6-month follow-up (1-3 day LOS: 2.4%; 4-6 day LOS: 2.7%; ≥7 day LOS: 4.2%).

Conclusion: Among this study population of hospitalized acutely ill patients in the USA, VTE pharmacologic prophylaxis was underutilized, regardless of the duration of hospital stay. However, the risk for VTE events was substantial, with nearly 10% of those with a ≥7 day LOS having suffered a VTE event within 6 months.