Clinical Briefs-By Louis Kuritzky, MD
Clinical Briefs-By Louis Kuritzky, MD
The Canadian CT Head Rule for Patients with Minor Head Injury
Minor head injury (mhi), de-fined as injuries associated with loss of consciousness, amnesia, or disorientation, and a Glasgow Coma Scale (GCS) score of 13-15, are an important public health concern, since as many as 1 million such cases are reported annually in North America. CT scans used in the course of evaluation for MHI have an extraordinarily low yield of pathology (0.7-3.7%), and, hence, represent a substantial financial burden.
In this prospective study, Stiell and colleagues developed a CT head decision rule based upon experience involving adult patients (n = 3121) with MHI and GCS scores of 13-15. CT was deemed merited only in persons who had positive responses to screening of high-risk and medium-risk criteria.
High-risk (for likelihood of neurologic intervention) criteria were: GCS score < 15 at 2 hours after injury, suspected open or depressed skull fracture, signs of basal skull fracture, > 2 vomiting episodes, or age > 65; medium-risk (for brain injury detected on CT) screening criteria were: amnesia before the impact lasting > 30 minutes, or what is described as a "dangerous mechanism" of injury, such as a pedestrian struck by a car, passenger thrown from a vehicle, or fall from height > 3 feet. Using the CT Head Rule should effectively reduce the ordering of CT scans by 32-54%.
Stiell IG, et al. Lancet. 2001;357:1391-1396.
Validation of Clinical Classification Schemes for Predicting Stroke: Results from the National Registry of Atrial Fibrillation
Hypertension is responsible for the highest attributable stroke risk, but of individual risk factors, atrial fibrillation (AF) is the most potent. Since antithrombotic therapies (ie, ASA, warfarin) have consistently demonstrated benefit for stroke prevention in AF, but the risk profiles for the 2 therapies are quite different, it is necessary for clinicians to have appropriate stratification schema to provide guidance in how best to apply such treatment.
Gage and colleagues examined data during 2121 patient-years of follow-up for AF patients, during which there were 94 strokes. To stratify patients, they incorporated information from the Atrial Fibrillation Investigators (AFI) and Stroke Prevention and Atrial Fibrillation (SPAF) investigators to form a composite risk classification scheme called CHADS2, which includes a single risk point for each of the following: congestive heart failure, hypertension, age > 75, and diabetes; stroke (or TIA) was assigned 2 points. According to this scoring system, for every point increase in CHADS2, the risk of stroke increases 1.5 fold.
ASA provides less stroke risk reduction than warfarin, but also provides less adverse event risk. Gage et al suggest that for patients with a CHADS2 risk of 0, aspirin would be the clearly preferred treatment.
Gage BF, et al. JAMA. 2001;285: 2864-2870.
High Density Lipoprotein Cholesterol and Ischemic Stroke in the Elderly
The linear relationship between cholesterol and CHD end points has not been clearly established with stroke. On the other hand, use of statins for persons with CAD has demonstrated impressive reductions in stroke, prompting closer scrutiny of the relationship between lipids, especially lipid subfractions, and cerebrovascular end points.
Sacco and colleagues used a population (n = 688) of persons older than age 39 suffering their first cerebral infarction, and compared these individuals on a case-control basis with 905 controls.
Higher levels of high-density lipoprotein (HDL; > 50 mg/dL) cholesterol were associated with a 0.5 odds ratio for stroke. The relationship of HDL to stroke did not change when LDL, triglycerides, ethnicity, gender, or race were factored in through multivariate analysis.
Previous trials have shown that use of statins for stroke prevention is of greater benefit for those with lower baseline HDL levels. Another recent trial using gemfibrozil in patients with isolated low HDL (LDL not elevated) resulted in favorable effect upon stroke and other vascular outcomes associated with improvements in HDL. Sacco et al suggest that greater attention to HDL as a cerebrovascular risk factor, and subsequent modification, may significantly affect the burden of stroke.
Sacco RL, et al. JAMA. 2001;285: 2729-2735.
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