Sunday, January 1, 2012
COAGULATION CORNER: JANUARY 2012
Just wanted to wish all of my readers a very happy and healthy 2012- all the best to you and your family!
January 2012: BLEEDING SCORES IN THE ASSESSMENT OF BLEEDING RISKS
One of the most effective tools in the assessment of bleeding is symptoms and bleeding history, however this is still a subjective evaluation. In order to standardize this quantitative bleeding assessment tools (BAT) have been developed. The issue is there are so many of them, their results may actually be conflicting. Questionnaires on bleeding history have been proposed, and validated as diagnostic tools by comparing data obtained from patients with normal controls.
Von Willebrand Disease
The Vincenza Bleeding Score (BS) has shown good sensitivity and specificity for the diagnosis of type 1 VWD. This can be integrated in a full diagnostic algorithm that also accounts for laboratory and family data and can be correlated with several biological variables, including VWF and FVIII:C levels, platelet function analyzer (PFA-100) closure times, and platelet glycoprotein haplotypes. . Collection of the BS at the time of the diagnosis may be a useful addition in the evaluation of the bleeding patients. In a study 215 patients were evaluated: bleeding symptoms (n = 71), abnormal laboratory clotting test results (n = 105) or family investigation (n = 39). Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were computed for a predefined bleeding score (BS) cut-off (BS of > 3). Receiver operating characteristic curves were used to establish a diagnostic prediction rule. Results: Assuming the prevalence of mild bleeding disorders (MBD) in the general population to be 1%, a normal BS (≤ 3) had a very high NPV (99.2%). The PPVs in patients referred for hemostatic or family evaluation were estimated to be 71.0% and 77.5% (assuming MDB prevalences of 20% and 50%, respectively, in these settings). Measurement of BS in addition to activated partial thromboplastin time significantly increased the diagnostic efficiency of the BAT instrument (NPV of 99.6%). BAT use improves the evaluation of patients with suspected MBD, and we propose its use in a clinical prediction guide based on BAT and activated partial thromboplastin time for the exclusion of patients with suspected MBD in a low-prevalence setting.
Warfarin is effective for the prevention of thromboembolism in a variety of conditions, but hemorrhage is a major side effect. Physicians use their clinical judgment to estimate the risk of bleeding in an individual patient. Prediction rules can help physicians more accurately weigh the risks and benefits of warfarin therapy. The Outpatient Bleeding Risk Index (BRI) included patients initiating warfarin upon discharge from the hospital, regardless of their indication for therapy, and prospectively classified patients who were at high-, intermediate-, or low-risk for major bleeding. This index considered age > 65 years, prior stroke, prior GI bleed, and any of four comorbidities (recent myocardial infarction, anemia, diabetes, or renal insufficiency) in order to stratify patients into three risk groups. In the original validation cohort, the index predicted major bleeding better than physicians, who estimated the probability of major bleeding no better than that expected by chance. The cumulative incidence at 48 months was 3% in 80 low-risk patients, 12% in 166 intermediate-risk patients, and 53% in 18 high-risk patients.
The second model was developed by Kuijer using age > 60 years, gender, and malignancy to stratify patients into three risk groups based on a calculation score with the formula (1.6 × age) + (1.3 × sex) + (2.2 × malignancy). They evaluated this score in an initial cohort of 241 patients with venous thromboembolism and, subsequently, in an independent cohort of 780 patients and found that it was possible to identify a subgroup of patients who would be high risk for bleeding, although clear discrimination was lacking in low-risk groups.
Non-ST-segment elevation myocardial infarction (NSTEMI):
The CRUSADE Bleeding Score was developed help clinicians estimate a patient's baseline risk of in-hospital major bleeding during non-ST-segment elevation myocardial infarction (NSTEMI). This initiative was designed to increase the practice of evidence-based medicine for patients diagnosed with non-ST segment elevation acute coronary syndromes (NSTE ACS) (i.e., unstable angina or NSTE myocardial infarction). Data include demographic and clinical information, medical history, use of antiplatelet, anti-thrombin and anti-ischemic therapies and use of invasive procedures, laboratory results, in-hospital outcomes, physician and hospital characteristics, and discharge medications and interventions.
Using data from over 89,000 "real-world" patients enrolled in the CRUSADE Quality Improvement Initiative that presented with NSTEMI. The CRUSADE Bleeding Score was created by assigning a weighted integer to each predictor based on its coefficient in the regression model. A patient's CRUSADE Bleeding Score equals the sum of the weighted scores for the independent predictors (range 1-100 points).
This core considers baseline patient characteristics (female sex, history of diabetes, peripheral vascular disease), admission clinical variables (heart rate, systolic blood pressure, signs of CHF), and admission laboratory values (hematocrit, calculated creatinine clearance) to estimate the patient's likelihood of having an in-hospital major bleed event (www.crusadebleedingscore.org). While treatments increase the likelihood of bleeding, they were not included in the model as they are post-admission variables.
A score for predicting bleeding risk in patients with atrial fibrillation (AF), has been developed called HAS-BLED. This is an easy assessment tool used to help doctors make informed decisions.
HAS-BLED stands for hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile INR, Elderly (>65), and drugs/alcholo concomitantly. Each component is 1 point with a maximum score of 9. Drugs include any medications that increase bleeding risks during anticoagulation (aspirin, NSAIDS, steriods).
The score can also be modified. For example, physicians can choose to stop aspirin to reduce bleeding risk or controlling hypertension.
Upper Gastrointestinal bleeding
In a study 16% of patients presenting with UGIB had a GBS score of "0", considered low. Among these patients there were no deaths or interventions needed and the patients were able to be effectively treated in an outpatient setting. In the validation group, scores of 6 or more were associated with a greater than 50% risk of needing an intervention.
Score is equal to "0" if the following are all present:
Clearly BATs come in a variety of shapes and sizes. Their goal, as is any scoring tool, is to remove subjectivity and provide a standardized assessment of a patient risk of bleeding.
The ISTH has established a new SSC standing committee: the ISTH-BAT Standing Committee. They have provided a tool that provides a web based accessible platform to aid in the standardization and collection of bleeding histories. This database will capture bleeding symptoms throughout the world encouraging sharing of de-identified phenotypic and laboratory data. This will enhance statistical power and provide important genotype-phenotype-environment correlations. This tool can be accessed online at:
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