Odds of Venous Thromboembolims (VTE) Associated with Hospitalization, Surgery, and Cancer Among Nursing Home Residents: A Population-Based Study.

Abstract 2984

Poster Board II-960

In previous studies of venous thromboembolism (VTE) among all residents of Olmsted County, MN, the odds of VTE associated with surgery, medical hospitalization, or active cancer were extremely high (Univariate odds ratio [OR] =14.6; 4.6, and 8.4 respectively). We also showed that nursing home (NH) residency was an independent risk factor for VTE (OR =5.6).

From a clinical practice perspective, it is important to identify which NH residents are at risk of VTE. While it might be assumed that, similar to estimates for the population generally, surgery, medical hospitalization, and cancer are associated with increased risk of VTE within the NH population, the answer remains unclear.

We took advantage of the previous identification of all Olmsted County, MN residents who met research criteria for incident VTE 1998-2005 (N=1168). We then determined which individuals were resident of a local NH at time of symptom onset, regardless of location of symptom onset (i.e., for purposes of this study, individuals whose VTE occurred in-hospital having been admitted from a NH were considered NH residents). For each such NH VTE case (N=96), we identified 2 same sex Olmsted County residents of similar age and duration-of-medical-history who were resident of a local NH at the time of the case's VTE event (i.e., index date) (N=192). The detailed provider-linked medical records of NH VTE cases and NH non-VTE controls were reviewed for 3 months before index for surgery or medical hospitalization and for 6 months surrounding index for active cancer. Using conditional logistic regression, we tested and estimated the odds ratio associated with each of these potential risk factors.

The proportions of NH VTE cases and NH non-VTE controls with surgery (33%, 28%), medical hospitalization (44%, 46%), and active cancer (12%, 9%) were similar. Univariate odds ratios (95% confidence intervals) and p values for surgery, medical hospitalization, and active cancer were 1.5 (0.7-3.1), p=0.30; 1.1 (0.6-2.1), p=0.74; and 1.4 (0.6-3.2), p=0.46 respectively.

Compared to the entire Olmsted County population, the odds of VTE associated with surgery, hospitalization, and cancer are surprisingly much lower for NH residents. Additional investigation is needed to characterize the subset of NH residents at increased risk of VTE.