Abstract P253: Impact of Hospital-Acquired Venous Thrombosis on Mortality in Medical Inpatients: The Medical Inpatients and Thrombosis (MITH) Study.

Abstract

Introduction: The Joint Commission mandates assessing risk and providing venous thrombosis (VT) prophylaxis in hospital inpatients. Pharmacologic VT prophylaxis reduces VT among medical inpatients, but the impact on survival is unknown. We studied the association of hospital acquired VT and VT prophylaxis with risk of inpatient mortality. Methods: We identified all cases of VT complicating medical admissions at a 500 bed teaching hospital in Burlington, Vermont from January 2002 to June 2009. VT cases were identified using ICD-9 codes, confirmed by medical record review, and frequency matched 1:2 to patients without VT by admission year and service (oncology, general medicine or cardiology). Death from VT was determined by medical record review and standardized criteria. We calculated odds ratios (OR) of death for hospital-acquired VT and VT prophylaxis using weighted multivariable logistic regression and 95% confidence intervals (CI) using the Taylor series method. Results: Of 64,334 admissions, 299 patients had hospital-acquired VT. 56 of these died from any cause and 24 died due to their VT. For every 1000 admissions, 87 ended in death and 4.6 had a hospital-acquired VT. Hospital-acquired VT was associated with increased odds of death, but this was attenuated by adjustment for other risk factors for death ( Table ). VT prophylaxis was inversely associated with odds of death when similarly adjusted ( Table ). Conclusions: One in 235 deaths in medical patients was attributable to hospital-acquired VT, a potentially preventable event. Occurrence of VT after admission in medical patients was associated with risk of death, but this was mediated by other patient characteristics. Findings suggest providing VT prophylaxis reduces risk of death in hospital, but this requires confirmation due to the low number of deaths in this study. Table Multivariable Model of Risk Factors for In-Hospital Mortality Risk Factor Unadjusted Odds Ratio (95% CI) Adjusted Odds Ratio (95% CI) * VT occurring during admission 2.41 (1.54, 3.77) 1.21 (0.58, 2.53) VT prophylaxis provided throughout admission ** 1.15 (0.51, 2.62) 0.48 (0.16, 1.45) * Model adjusted for the following (measured on admission unless indicated): sex, age, systolic blood pressure, diastolic blood pressure, heart rate, hypoxic or ventilated, pneumonia, metastatic cancer, history of myocardial infarction, dementia, use of full anticoagulation, VT prophylaxis stopped during admission, admitted or transferred to intensive care. ** Reference group: no prophylaxis or anticoagulation during admission.