Clinical Briefs in Primary Care
The Canadian CT Head Rule for Patients with Minor Head Injury
Source: Stiell IG, et al. Lancet. 2001; 357:1391-1396.
Minor head injury (MHI), defined 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%.
Validation of Clinical Classification Schemes for Predicting Stroke: Results from the National Registry of Atrial Fibrillation
Source: Gage BF, et al. JAMA. 2001;285:2864-2870.
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.
High Density Lipoprotein Cholesterol and Ischemic Stroke in the Elderly
Source: Sacco RL, et al. JAMA. 2001;285:2729-2735.
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.
Microalbuminuria as a Marker of Preclinical Diastolic Dysfunction in Never-Treated Essential Hypertensives
Source: Grandi AM, et al. Am J Hypertens. 2001;14:644-648.
Normal urinary albumin excretion does not exceed 30 mg/24 h. Microalbuminuria (MAU), defined as 30-300 mg/24 h albumin excretion, is seen in hypertensive and diabetic patients and has been shown to reflect, in addition to propensity for decline in renal function, cardiovascular risk. For instance, MAU is associated with greater incidence of left ventricular hypertrophy (LVH) and LV systolic dysfunction (SDF). LV diastolic dysfunction (DDF) is considered one of the earliest detectable myocardial derangements attributed to hypertension, antedating SDF, but studies have not previously been done relating MAU to DDF in never-treated hypertensives.
This study included never-treated hypertensives (n = 87) that were divided into MAU+ (= 30-300 mg/d albuminuria) and MAU- (= normal albumin excretion) categories, and evaluated for DDF. Diastolic function, as measured by peak LV lengthening rate, was found in MAU+ patients 3 times as often as MAU- patients (67.8% vs 22%).
Grandi and colleagues conclude that in addition to the acknowledged association between MAU+ and other cardiovascular risk, MAU+ is associated with impairment of diastolic ventricular function in asymptomatic hypertensive patients.
Smoking Cessation and the Course of Major Depression: A Follow-Up Study
Source: Glassman AH, et al. Lancet. 2001;357:1929-1932.
It has been previously noted that persons attending smoking-cessation clinics have a statistically greater frequency of past episodes of depression than nonsmoking comparators. Additionally, previous depression is linked with smoking recidivism.
The issue of new episodes of major depression attendant to smoking cessation efforts has been little examined. Glassman and colleagues examined 100 smokers with a previous history of major depression who participated in a smoking cessation trial for 2 months. Sertraline was the active agent used to assist smoking cessation (placebo controlled). Patients were not taking antidepressant medications during the 6- month observation period after smoking cessation intervention.
Comparing persons who successfully stopped smoking with those who continued to smoke, the frequency of major depression was 5 times as likely among abstinent persons (31% vs 6%). Interestingly, among abstinent smokers, those who had used placebo were twice as likely to suffer subsequent depression than the group who received active pharmacotherapy (43% vs 19%). Glassman et al conclude that smoking cessation is associated with an elevated risk of recurrence of depression; nicotine may have some effect that alters vulnerability to depression. The evenly distributed frequency of depressive episodes throughout the 6 months postcessation observation period argues against a "sertraline halo" effect.
Prophylaxis with Single-Dose Doxycycline for the Prevention of Lyme Disease After an Ixodes Scapularis Tick Bite
Source: Nadelman RB, et al. N Engl J Med. 2001;345:79-84.
Though lyme disease may be prevented by vaccination, the cost and need for multiple doses are substantial obstacles to implementation, in addition to imperfect protective effects. To test the applicability of using single-dose pharmacotherapy (200 mg doxycycline PO) in persons who have recently suffered a tick bite from Ixodes scapularis, Nadelman and colleagues performed a placebo-controlled trial (n = 482) among persons who had removed a tick within 72 hours of attachment. Subjects underwent physical examination, blood cultures, and Borrelia burgdorferi antibody tests at baseline, 3 weeks, and 6 weeks.
Erythema migrans was infrequent, but doxycycline did statistically significantly reduce its occurrence (0.4% vs 3.2%). In regard to the primary end point of the trial (development of erythema migrans), the overall efficacy of doxycycline was 87%.
Nadelman et al conclude that when given within 72 hours of a recognized tick bite, a single dose of 200 mg of doxycycline is highly effective in preventing development of Lyme disease.
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