Routine deep vein thrombosis screening after lung transplantation: Incidence and risk factors

Abstract

BackgroundDeep vein thrombosis (DVT) remains a common complication following lung transplantation despite universal routine DVT screening. Moreover, many of the previously reported risk factors are incompletely defined. We sought to explore the influence of DVT screening and to more definitively assess predisposing risk factors. MethodsA single-institution, retrospective, cohort study of 1141 patients undergoing lung transplantation from January 1, 2005, to December 31, 2014, was performed evaluating for the rate of DVT. Patients were given prophylactic subcutaneous heparin postoperatively. DVT events were noted if they occurred before 90 days after transplant. We compared DVT rates before and after 2008 when universal screening was implemented. We also evaluated the timing of DVT event and location (above the knee vs below the knee). DVTs were treated with standard anticoagulation therapy or an inferior cava filter when patients were unable to tolerate anticoagulation treatment. Univariable and multivariable models were used to identify risk factors for occurrence. A propensity match was performed to match groups across the eras, and a Cox regression was performed to identify differences in 1-year survival trajectory between cohorts. ResultsThe rates of DVT before and after routine screening were 8.8% (36 DVT out of 412 transplants) and 17.3% (126 out of 729 transplants), respectively. These 2 rates were significantly different (P < .01); moreover, the observed DVT incidence per year was not significantly different across the 6 years after universal DVT screening was implemented (P > .90 for all comparisons). Observed DVT incidence at day 0 and day 14 were 3.8% and 3.8%, respectively, for the cohort before DVT protocols were established. Observed DVT incidence for the cohort after protocols were established at the same time points was 8.7% and 3.7%, respectively. Univariable analysis revealed that significant factors associated with a DVT include hypercholesterolemia (odds ratio [OR], 6.90; 95% confidence interval [CI], 1.82-26.13; P < .01), the number of days in the intensive care unit (OR, 1.03; 95% CI, 1.00-1.01; P < .01), and the length of stay in the hospital (OR, 1.01; 95% CI, 1.01-1.02; P < .01), whereas having quit smoking (vs never smoked) was associated with a decrease in DVT development (OR, 0.50; 95% CI, 0.33-0.75; P < .01). Multivariable analysis revealed 2 significant variables: hypercholesterolemia (OR, 8.13; 95% CI, 1.22-54.37; P = .03) and length of stay (OR, 1.03; 95% CI, 1.01-1.05; P < .01). There was a trend for better 1-year survival in the post-2008 era (Exp[β], 1.49; P = .09). ConclusionsThe rate of DVT diagnosis significantly increased after universal DVT screening was implemented. Furthermore, those patients undergoing lung transplantation with extended length of stay and hypercholesterolemia were prone to increased rates of DVT. There was a trend toward better 1-year survival in DVT-screened patients, suggesting DVT screening may result in beneficial outcomes.