Hospitalization-associated VTE attack (incident plus recurrent VTE) rates over the 6-year period, 2005-2010, did not change significantly despite achieving near-universal in-hospital VTE prophylaxis; 75% of these VTE events occurred after hospital discharge with a median of 19.5 days from hospital discharge to VTE. The median durations of hospitalization and in-hospital prophylaxis were 3 days and 70 hours, respectively, suggesting that VTE prophylaxis was inadequate. However, the hospital population that would benefit most from post-hospitalization VTE prophylaxis is uncertain. Our study aim was to test hospital length of stay (LOS) as a potential predictor of post-hospital-discharge incident or recurrent VTE.
Using the resources of the Rochester Epidemiology Project, we identified all unique Olmsted County, MN residents hospitalized at least once at a Rochester, MN Mayo Clinic hospital and all such residents with objectively-diagnosed occurrence of first or recurrent VTE during hospitalization or within 92 days after hospital discharge, 2005-2010. We tested LOS as a potential predictor of post-hospital-discharge VTE (conditional on surviving to hospital discharge free of VTE) using the Anderson-Gill version of Cox regression modeling and adjusting for age, sex, any surgery performed during that hospitalization, and Charlson Comorbidity Index calculated from conditions recorded from 1/1/2005 until the day of hospital discharge.
Over the period, 2005-2010, 31,588 unique Olmsted County residents were hospitalized at least once at a Rochester Mayo Clinic hospital. The distribution of LOS was: 1-2 (3.8%), 3 (24.2%), 4 (23.3%), 5 (16.4%), 6 (8.8%), 7-9 (12.4%), 10-19 (8.4%) and 20+ (2.3%). Of the 253 VTE events identified within 92 days post-hospital discharge, 6, 29, 31, 38, 38, 53, 42 and 16 had been hospitalized for 1-2, 3, 4, 5, 6, 7-9, 10-19 and 20+ days, respectively. The hazard ratios (HR) for post-hospital-discharge VTE were similar for hospital LOS ≤4 days; compared to LOS ≤3 days, the HRs were significantly increased for hospital LOS of 5 (HR=1.78), 6 (HR=2.86), 7-9 (HR=2.71), 10-19 (HR=3.16) and 20+ (HR=4.20) days (Table 1).
The adjusted hazards of post-hospital discharge VTE for hospital LOS > 4 days were significantly increased 1.8 to 4.2-fold compared to LOS ≤3 days, suggesting that hospital LOS may be useful for identifying hospitalized patients suitable for longer duration VTE (including post-discharge) prophylaxis. Future studies should be aimed at identifying additional predictors of post-hospital-discharge VTE such that extended prophylaxis can be targeted to those patients who would benefit most.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.