Background: Venous thromboembolisms (VTEs) are a significant cause of mortality in hospitalized patients and a burden to hospital resources (Khera, SA, 2014; Lyman, GA, 2014). Besides the known risk factors for VTE as mentioned by multiple past studies (Goldhaber, SZ, 2010; Martinelli, I, 2001; Heit, JA, 2002; and Ocak, G, 2013), there has been no study, to our knowledge, that has determined if transferred patients are at a higher risk for VTE
Methods: Utilizing the University Health Consortium (UHC) Database, we looked at VTE rates in transferred and non-transferred patients in the years 2012, 2013 and 2014. This was completed using the Clinical Database Resource Manager (CDRM) provided by UHC. We determined the VTE rates in transferred patients and non-transferred patients in all listed institutions. We utilized a chi-square analysis on an aggregate of all hospitals in the above years. Statistical significance was assigned to p-value of < 0.05. Two variables we were able to obtain from the UHC Database were “Level 1 Trauma” status and “Case-Mix Index” (CMI). We ran separate chi-square analyses for these two variables as well.
Results: For the years 2012-2014, a total of 225 hospitals and 12,039,520 patients were separated into transferred patients (1,445,786 patients) and non-transferred patients (10,593,734 patients). While the total incidence rate averaged 2.09% over 3 years, the incidence of VTE in transferred patients versus non-transferred patients was 3.43% versus 1.91% (RR 1.80, p = <0.001). VTE incidence in Level 1 Trauma Centers for transferred versus non-transferred patients was 3.44% versus 1.88% (RR 1.83, p = <0.001). The CMI over this time period for all 251,926 VTE patients in transferred versus non-transferred patients was 3.53 versus 2.44 (p = <0.001). This significant difference in VTE rates was maintained (p = <0.001) even after stratifying for Level 1 trauma centers (transfer rate 13.36%) versus non-Level 1 trauma centers (transfer rate 10.55%).
Conclusions: Across all variety of hospitals over a three year period, our analysis found that transfer status was correlated with a higher risk for developing VTEs. Level 1 Trauma Centers were also noted to have a statistically significant increased rate of VTEs in their transferred patients. Lastly, the CMI was significantly higher in transferred patients, meaning that these patients are more ill than their non-transferred counter-parts. We believe that further studies are needed to elucidate appropriate screening of transferred patients and the impact to higher-level of care institutions on hospital acquired VTE penalties. This also raises the question of the potential utilization of ultrasound screening in transferred patients and further studies to define its role.