Incidence and Risk Factors for Thromboembolism in Patients with Hematologic Malignancies Undergoing Allogeneic and Autologous Stem Cell Transplantation.

Background: Thromboembolism (TE) is a common complication of hospitalized non-transplant cancer patients. To date, the extent and impact of TE in stem cell transplant patients is unknown, in part because it is considered a low risk group given the high prevalence of thrombocytopenia. The purpose of this study is to evaluate the incidence of and risk factors for TE in cancer patients undergoing stem cell transplantation.

Methods: We conducted a retrospective analysis of all discharge summaries from the 115 US academic health centers reporting to the University HealthSystem Consortium from 1995 to 2002. We identified a total of 7,087 patients with hematologic malignancies undergoing allogeneic and autologous stem cell transplantation. The incidence of and risk factors for venous and arterial TE was analyzed in univariate and multivariate logistic regression analysis with adjusted odds ratios as estimates of relative risk.

Results: TE was reported in 389 (5.5%) transplant patients with 4.8% patients developing venous and 0.7% arterial TE. The incidence of TE was greater in allogeneic (6.8%) compared to autologous (4.8%) transplant patients (p<0.0001). Among those receiving allogeneic transplantations, BMT patients experienced a higher rate of TE than PBSC patients (7.5% vs 5.6%; p<0.05). In multivariate logistic regression analysis, the following clinical variables were significantly associated with TE in stem call transplant patients with hematologic malignancies: gram negative sepsis (OR=1.76; 1.02–3.02; p=0.04), gram positive sepsis (OR=1.75; 1.25–2.45; p=0.001), line infections (OR=1.48; 1.11–1.97; p=0.008), central venous catheters (OR=1.74; 1.39–2.17; P<0.0001), pulmonary disease (OR=1.87; 1.47–2.37; p<0.0001), liver disease (OR=1.31; 1.01–1.70; p=0.04) and length of stay >30 days (OR=1.66; 1.30–2.13; p<0.0001). Hodgkin’s disease (OR= 0.59; 0.37–0.94; p=0.026) was associated with a lower risk of TE. In multivariate analysis, the type of transplant failed to remain an independent risk factor for TE after controlling for other transplant complications.

Conclusions: This is the first substantive report on the incidence of thromboembolism in stem cell transplant patients. We found that thromboembolic events are a frequent complication in patients with hematologic malignancies undergoing stem cell transplantation. The incidence of TE is high among most subgroups studied. Prospective studies are needed to evaluate the efficacy and safety of thromboprophylaxis in this high-risk population.