Performance of four clinical decision rules in patients with malignancy and suspected pulmonary embolism

Diagnostic Approach for Venous Thromboembolism in Cancer Patients

Venous thromboembolic disease (VTE) is a common complication in cancer patients. The currently recommended VTE diagnostic approach involves a step-by-step algorithm, which is based on the assessment of clinical probability, D-dimer measurement, and/or diagnostic imaging. While this diagnostic strategy is well validated and efficient in the noncancer population, its use in cancer patients is less satisfactory. Cancer patients often present nonspecific VTE symptoms resulting in less discriminatory power of the proposed clinical prediction rules. Furthermore, D-dimer levels are often increased because of a hypercoagulable state associated with the tumor process. Consequently, the vast majority of patients require imaging tests. In order to improve VTE exclusion in cancer patients, several approaches have been developed. The first approach consists of ordering imaging tests to all patients, despite overexposing a population known to have mostly multiple comorbidities to radiations and contrast products. The second approach consists of new diagnostic algorithms based on clinical probability assessment with different D-dimer thresholds, e.g., the YEARS algorithm, which shows promise in improving the diagnosis of PE in cancer patients. The third approach uses an adjusted D-dimer threshold, to age, pretest probability, clinical criteria, or other criteria. These different diagnostic strategies have not been compared head-to-head. In conclusion, despite having several proposed diagnostic approaches to diagnose VTE in cancer patients, we still lack a dedicated diagnostic algorithm specific for this population.

Usefulness of Clinical Prediction Rules, D-dimer, and Arterial Blood Gas Analysis to Predict Pulmonary Embolism in Cancer Patients

OBJECTIVES

Pulmonary embolism (PE) is seven times more common in cancer patients than non-cancer patients. Since the existing clinical prediction rules (CPRs) were validated predominantly in a non-cancer population, we decided to look at the utility of arterial blood gas (ABG) analysis and D-dimer in predicting PE in cancer patients.

METHODS

Electronic medical records were reviewed between December 2005 and November 2010. A total of 177 computed tomography pulmonary angiograms (CTPAs) were performed. We selected 104 individuals based on completeness of laboratory and clinical data. Patients were divided into two groups, CTPA positive (patients with PE) and CTPA negative (PE excluded). Wells score, Geneva score, and modified Geneva score were calculated for each patient. Primary outcomes of interest were the sensitivities, specificities, positive, and negative predictive values for all three CPRs.

RESULTS

Of the total of 104 individuals who had CTPAs, 33 (31.7%) were positive for PE and 71 (68.3%) were negative. There was no difference in basic demographics between the two groups. Laboratory parameters were compared and partial pressure of oxygen was significantly lower in patients with PE (68.1 mmHg vs. 71 mmHg, p = 0.030). Clinical prediction rules showed good sensitivities (88-100%) and negative predictive values (93-100%). An alveolar-arterial (A-a) gradient > 20 had 100% sensitivity and negative predictive values.

CONCLUSIONS

CPRs and a low A-a gradient were useful in excluding PE in cancer patients. There is a need for prospective trials to validate these results.

Performance of the age-adjusted cut-off for D-dimer in patients with cancer and suspected pulmonary embolism

BACKGROUND

Cancer patients frequently present with suspected pulmonary embolism (PE). The D-dimer (DD) test is less useful in excluding PE in cancer patients due to the lower specificity. In the general population, the age-adjusted cutoff for DD combined with a clinical decision rule (CDR) improved specificity in the diagnosis of PE.

OBJECTIVES

To evaluate the safety and efficacy of the age-adjusted cutoff (defined as age∗10μg/L in patients >50years) combined with a CDR for the exclusion of PE in cancer patients.

METHODS

We conducted a prospective study to evaluate the age-adjusted cutoff in patients with suspected PE. Here we report a post-hoc analysis on the performance of the age-adjusted cutoff in patients with and without cancer. The primary outcome was the rate of venous thromboembolic events (VTE) during three-month follow-up.

RESULTS

Of 3324 patients with suspected PE, 429 (12.9%) patients had cancer. The prevalence of PE was 25.2% in cancer patients and 18% in patients without cancer (p<0.001). Among cancer patients with an unlikely CDR, 9.9% had a DD <500μg/L as compared with 19.7% using the age-adjusted cutoff. In patients without cancer, these rates were 30.1% and 41.9%. The proportion of cancer patients in whom PE could be excluded by CDR and DD doubled from 6.3% to 12.6%. No VTE occurred during three-month follow-up (failure rate 0.0% (95% CI 0.0-6.9%)).

CONCLUSION

Compared with the conventional cutoff, the age-adjusted D-dimer cutoff doubles the proportion of patients with cancer in whom PE can be safely excluded by CDR and DD without imaging.

The diagnosis and treatment of venous thromboembolism

Venous thromboembolism (VTE) is a common condition that can lead to complications such as postphlebitic syndrome, chronic pulmonary artery hypertension, and death. The approach to the diagnosis of has evolved over the years and an algorithm strategy combining pretest probability, D-dimer testing, and diagnostic imaging now allows for safe, convenient, and cost-effective investigation of patients. Patients with low pretest probability and a negative D-dimer can have VTE excluded without the need for imaging. The mainstay of treatment of VTE is anticoagulation, whereas interventions such as thrombolysis and inferior vena cava filters are reserved for special situations. Low-molecular-weight heparin has allowed for outpatient management of most patients with deep vein thrombosis at a considerable cost savings to the health care system. Patients with malignancy-associated VTE benefit from decreased recurrent rates if treated with long-term low-molecular-weight heparin. The development of new oral anticoagulants further simplifies treatment. The duration of anticoagulation is primarily influenced by underlying cause of the VTE (whether provoked or not) and consideration of the risk for major hemorrhage. Testing for genetic and acquired thrombophilia may provide insight as to the cause of a first idiopathic deep vein thrombosis, but the evidence linking most thrombophilias to an increased risk of recurrent thrombosis is limited.