Abstract

Background

Venous thromboembolism (VTE) is a frequent complication in patients with underlying cancer. This risk is higher during hospitalization for acute medical conditions. Consequently, routine thromboprophylaxis is recommended in hospitalized cancer patients. A retrospective review of admissions to the Leukemia/Bone Marrow Transplant (LBMT) unit at our institution between January and June 2010 demonstrated that VTE prophylaxis was prescribed in only 6.6% of admissions. In March 2012, a mandatory VTE risk assessment and thromboprophylaxis protocol was introduced in the LBMT unit as part of a hospital-wide policy to improve thromboprophylaxis compliance for all hospitalized patients.

Objectives

The primary goal is to assess the impact of the VTE thromboprophylaxis protocol on the use of thromboprophylaxis in the LBMT unit. Secondary aims of this study are to evaluate the incidence of VTE (including catheter-related thrombosis [CRT]) and bleeding after the introduction of the protocol.

Methods

A retrospective chart review of all admissions to the Vancouver General Hospital LBMT unit between March 1, 2012 and February 28, 2013 was performed (intervention cohort [IC]). Only the first admission for each patient during the study period was included in the analysis. Data were extracted from electronic medical records using standardized forms. The primary outcome, rate of VTE prophylaxis, was compared to historical data from January 2010 to June 2010 (historical cohort [HC]).

Results

361 patients were included in the IC and 166 patients were included in the HC. All baseline patient characteristics, thrombotic risk factors and bleeding risk factors were similar between the cohorts with the exception of the presence of thrombocytopenia (82.0% IC vs. 68.7% HC, p=0.001) (Table 1 

Table 1

Patient Characteristics.

Historical CohortIntervention Cohort
 N=166 N=349 
Median age (range), years 52 (18-76) 55 (18-84) 
Median length of stay (range), days 19 (2-182) 18 (1-221) 
Male Sex, n (%) 102 (61.4) 218 (60.4) 
Underlying diagnosis, n (%)   
Acute leukemia 86 (51.8) 155 (42.9) 
Lymphoma 47 (28.3) 94 (26) 
Myelodysplastic syndrome 5 (3.0) 14 (3.9) 
Multiple myeloma 14 (8.4) 47 (13) 
Chronic myeloid leukemia 4 (2.4) 15 (4.2) 
Aplastic anemia 4 (2.4) 10 (2.8) 
Other 6 (3.6) 26 (7.2) 
Treatment Received During Admission, n (%)   
Chemotherapy 65 (39.1) 162 (44.9) 
Stem cell transplant 54 (32.6) 94 (26) 
Immunosuppressive therapy 5 (3.0) 12 (3.3) 
Supportive Care 42 (25.3) 91 (25.2) 
Other 0 (0) 8 (2.2) 
Thrombotic Risk Factors, n (%)   
Second active malignancy 3 (1.8) 3 (0.8) 
Indwelling catheter 144 (87.6) 307 (85) 
Prior VTE 16 (9.6) 33 (9.1) 
Surgery within 3 months of admission 3 (1.8) 8 (2.2) 
Surgery during admission 6 (3.6) 22 (6.4) 
Bleeding Risk Factors, n (%)   
Thrombocytopeniaa 114 (68.7) 296 (82) 
Coagulopathyb 8 (4.8) 14 (3.9) 
Renal dysfunctionc 15 (9.0) 33 (9.1) 
Hepatic Dysfunctiond 38 (22.9) 101 (28) 
Historical CohortIntervention Cohort
 N=166 N=349 
Median age (range), years 52 (18-76) 55 (18-84) 
Median length of stay (range), days 19 (2-182) 18 (1-221) 
Male Sex, n (%) 102 (61.4) 218 (60.4) 
Underlying diagnosis, n (%)   
Acute leukemia 86 (51.8) 155 (42.9) 
Lymphoma 47 (28.3) 94 (26) 
Myelodysplastic syndrome 5 (3.0) 14 (3.9) 
Multiple myeloma 14 (8.4) 47 (13) 
Chronic myeloid leukemia 4 (2.4) 15 (4.2) 
Aplastic anemia 4 (2.4) 10 (2.8) 
Other 6 (3.6) 26 (7.2) 
Treatment Received During Admission, n (%)   
Chemotherapy 65 (39.1) 162 (44.9) 
Stem cell transplant 54 (32.6) 94 (26) 
Immunosuppressive therapy 5 (3.0) 12 (3.3) 
Supportive Care 42 (25.3) 91 (25.2) 
Other 0 (0) 8 (2.2) 
Thrombotic Risk Factors, n (%)   
Second active malignancy 3 (1.8) 3 (0.8) 
Indwelling catheter 144 (87.6) 307 (85) 
Prior VTE 16 (9.6) 33 (9.1) 
Surgery within 3 months of admission 3 (1.8) 8 (2.2) 
Surgery during admission 6 (3.6) 22 (6.4) 
Bleeding Risk Factors, n (%)   
Thrombocytopeniaa 114 (68.7) 296 (82) 
Coagulopathyb 8 (4.8) 14 (3.9) 
Renal dysfunctionc 15 (9.0) 33 (9.1) 
Hepatic Dysfunctiond 38 (22.9) 101 (28) 

aplatelets <50 x 109/L; bINR > 2.0 without warfarin; ccreatinine >200 μmol/L; dbilirubin > twice upper limit of normal (ULN) or transaminases > 3 x ULN.

). At least one dose of thromboprophylaxis was prescribed in 14.0% of admissions in the IC vs. 6.6% of admissions in the HC. This increase was statistically significant (p=0.01). Despite the low prophylaxis prevalence, VTE was uncommon, occurring in only 1.9% patients in the IC (pulmonary embolism [PE] in 5 patients, CRT in 1 patient and left ventricular thrombus in 1 patient) vs. 2.4% patients in the HC (deep vein thrombosis +/- PE in 3 patients, CRT and PE in 1 patient) (p=0.7). In contrast, bleeding complications were frequent (even in the absence of anticoagulants), with 13.3% of patients in the IC and 19.3% of patients in the HC experiencing at least one bleeding episode (p=0.08). 22 patients (6.1%) in the IC and 8 patients (4.8%) in the HC died during the study period. While fatal bleeding events occurred in 2 patients in each cohort in the absence of anticoagulation, no deaths due to VTE were observed.

Conclusions

After introduction of a standardized protocol, VTE prophylaxis rate in hospitalized LBMT patients significantly increased by over 2-fold but remains low. No changes in bleeding and VTE rates were observed despite the increase in prophylaxis compliance. Although thrombocytopenia is likely the prime reason for withholding prophylaxis, further review is ongoing to elucidate the reasons why thromboprophylaxis was not prescribed in the majority of patients.

Disclosures:

No relevant conflicts of interest to declare.

Author notes

*

Asterisk with author names denotes non-ASH members.