Two common scoring systems include the Geneva and Wells criteria, which employ a combination of historical information, clinical and laboratory data to stratify patients into three risk groups.1,2 It has recently been shown that a single negative D-dimer test safely excludes patients with suspected VTE in a large cohort, with a three-month follow-up rate of VTE of 0%.3 Criticism of current clinical probability assessment strategies include the inclusion of subjective criteria or the need for blood gas values.1,2 In this paper, the authors sought to derive and validate a scoring system based on readily available objective clinical data.
Methods: The cohort evaluated in this study consists of the same 965 patients used to prospectively evaluate an emergency department diagnostic strategy of VTE.3 Patients presenting to the emergency ward with complaints of chest pain or shortness of breath were evaluated with a standard diagnostic workup that included a checklist of demographic and historical information, signs and symptoms possibly consistent with VTE, ABG, chest X-ray, and EKG results, as well as the likelihood of another diagnosis. However, the goal was to create a scoring system based on readily available objective data, so ABG, chest X-ray and electrocardiogram results were not evaluated as possible components of the score. Clinical variables associated with pulmonary embolism were evaluated for statistical significance in both a univariate and multivariate model. These variables were then validated both internally and with an external cohort.
Results: The incidence of VTE was 23% (222/965). Ten clinical variables were found to be statistically significantly associated with VTE; these comprise the Revised Geneva Score.
Clinical probability is based on points: 0-3 is low probability; 4-10 is intermediate probability, and >10 is high probability. Low, intermediate, and high clinical probabilities had respective rates of VTE of 8%, 28%, and 74%. These percentages were found in the validation cohort and were similar to those in the derivation cohort.
Discussion: This study focuses on the derivation and validation of a clinical scoring system that can provide a numerical estimate of likelihood of VTE. The diagnostic strategy by which VTE is confirmed or excluded is from derivation cohort and is published elsewhere.3 In that study patients classified as no VTE and not treated had a 90-day risk of VTE of 1%. The nine-point revised Geneva score does indeed provide an accurate assessment of risk of VTE, and can thus help guide clinical decision-making. However it is not clear that the revised Geneva score will help decrease invasive diagnostic tests. In the low-risk group, 8% is too great a risk of a life-threatening illness to forego further diagnostic evaluation. Coupled with a negative ELISA D-dimer, exclusion of these patients is safe, but these patients cannot be safely excluded without risk stratification.3
- Wells PS, Anderson DR, Rodger M, et al. Derivation of a simple clinical model to categorize patients’ probability of pulmonary embolism: increasing the model’s utility with the SimpliRED D-dimer. Thromb Haemost. 2000 Mar;83:416-420.
- Wicki J, Perneger TV, Junof AF, et al. Assessing clinical probability of pulmonary embolism in the emergency ward: a simple score. Arch Intern Med. 2001 Jan 8;161(1):92-97.
- Perrier A, Roy PM, Aujesky D, et al. Diagnosing pulmonary embolism in outpatients with clinical assessment, D-dimer measurement, venous ultrasound and helical computed tomography: a multicenter management study. Am J Med. 2004 Mar 1;116(5):291-299.
LMWH for Inpatient Palliative Care
By Jeanie Youngwerth, MD
Noble SI, Nelson A, Turner C, et al. Acceptability of low molecular weight heparin thromboprophylaxis for patients receiving palliative care: qualitative study. BMJ. 2006 Mar 11:332(7541);577-580.ePub 2006 Feb 3.