Clinical Health Updates

NT-BNP reduces cost and rehospitalization rates in dyspneic patients.

Clinical Question:
Does the use of B-natriuretic peptide testing improve clinical and economic outcomes in patients hospitalized with dyspnea?

Bottom Line:
The use of the N-terminal B natriuretic peptide (NT-BNP) reduces the cost of care, the length of the emergency department (ED) visit, and the likelihood of rehospitalization when used in the evaluation of patients presenting to the ED with dyspnea. However, it does not reduce mortality or hospital length of stay.

Reference:
Moe GW, Howlett J, Januzzi JL, Zowall H; Canadian Multicenter Improved Management of Patients With Congestive Heart Failure (IMPROVE-CHF) Study Investigators. N-terminal pro-B-type natriuretic peptide testing improves the management of patients with suspected acute heart failure: primary results of the Canadian Prospective Randomized Multicenter IMPROVE-CHF study. Circulation 2007;115(24):3103-3110.

Study Design:
Randomized controlled trial (single-blinded)

Synopsis:
Sometimes new tests are just, well, more tests. Ultimately, we should not only ask whether a new test is accurate (disease-oriented evidence), but also ask whether the use of the test improves clinical outcomes. This is one of the few studies to do just that. The authors of this study, sponsored by the test manufacturer, identified 534 adults presenting to a Canadian ED with dyspnea. Patients with advanced renal disease, acute myocardial infarction, malignancy, and dyspnea due to “clinically overt” origins, such as pneumothorax or chest trauma, were excluded, leaving 500 patients for the final study. The ED physician was asked to commit to a diagnosis of heart failure or no heart failure without knowledge of NT-BNP. Patients were then randomized to receive care guided by NT-BNP or care without knowledge of that test result. The results of the test were given to the ED physician and all physicians involved in the patient’s care, and the test was repeated 72 hours later in hospitalized patients. The final diagnosis of heart failure (present in 46% of patients) was made by 2 cardiologists who were given all of the clinical data except the NT-BNP result (having knowledge of the NT-BNP result as part of the reference standard would bias the study and inflate the accuracy of the test).

Patients were followed up at 60 days for clinical and economic outcomes. Groups were balanced at the start of the study, and analysis was by intention to treat. Patients in the group whose care was informed by the NT-BNP result had a shorter ED visit (5.6 vs 6.3 hours; P = .03), lower total direct cost (CAN $5180 vs $6129; P = .02), and fewer rehospitalizations (13% vs 20%; P = .046). There was also a nonsignificant trend toward less use of outpatient diagnostic testing, but no difference in hospital length of stay or mortality rates. Benefits were greater in patients with an intermediate clinical probability of heart failure; that is, those for whom the diagnosis was in question. The researchers also looked at the accuracy of clinical judgment alone versus judgment supplemented by the NT-BNP result, and found that the test increased the accuracy of diagnosis (area under the receiver operating characteristic curve 0.90 vs 0.83, where 1.0 = a perfect test and 0.5 = a worthless test).

MRI = contrast enhanced CT for assessment of acute pancreatitis

Clinical Question:
Is nonenhanced magnetic resonance imaging comparable with contrast enhanced computed tomography for assessing severity and predicting outcome in patients with acute pancreatitis?

Bottom Line:
NEMRI is comparable to CECT in the early assessment of the severity of AP, and both methods are equally efficient in predicting local and systemic complications of AP. MRI has a potential advantage over CT in detecting bile duct lithiasis and pancreatic hemorrhage.

Reference:
Stimac D, Miletic D, Radic M, et al. The role of nonenhanced magnetic resonance imaging in the early assessment of acute pancreatitis. Am J Gastroenterol 2007;102:997-1004.

Study Design:
Diagnostic test evaluation

Synopsis:
Consecutive patients admitted with acute pancreatitis were included. Between the third and fifth hospital days, patients underwent spiral computed tomography with intravenous contrast and NEMRI, including MR cholangiopancreatography (MRCP). Fourteen patients were excluded because of contrast allergy, metal implants, and inability to undergo MRI because of mechanical ventilation. Two radiologists who were masked to patients’ clinical data independently reviewed both imaging studies. Disease severity on imaging was graded by the Balthazar grade, a scoring system based on radiographic findings of pancreatic enlargement, inflammation, fluid collections, and percent necrosis. This was compared with clinical disease severity, as assessed primarily with the Atlanta criteria, and secondarily with several other prognostic measures including the Ranson score, the Acute Physiology and Chronic Health Outcomes (APACHE) II score, and C-reactive protein levels.

A total of 101 patients were studied. The patients’ median age was 62 years and the causes of acute pancreatitis were primarily biliary (63%) and alcoholic (18%). Pancreatitis was classified as severe according to the Atlanta score in approximately 33% of patients, and by the Ranson score in 64% (Ransom score > 2). CECT and NEMRI showed significant correlation for Balthazar grade, assessment of pancreatic necrosis, and combined severity indices (Balthazar grade plus points for percent necrosis). Magnetic resonance severity indices also correlated with the Ranson score, systemic complications, and length of hospital stay. Using CECT as the gold standard, NEMRI had a sensitivity of 79% and specificity 92% for detection of severe pancreatitis (positive likelihood ratio = 10; negative likelihood ratio = 0.23).

Rapid antigen test reduces antibiotic use in adult sore throat

Clinical Question:
What is the best strategy for diagnosing strep throat in adults?

Bottom Line:
The use of a rapid antigen test reduces antibiotic use in adults with sore throat better than usual care and better than the use of a clinical decision rule alone. A combined approach using a clinical decision rule plus a rapid antigen test when the clinical rule is equivocal may be the most efficient approach.

Reference:
Worrall G, Hutchinson J, Sherman G, Griffiths J. Diagnosing streptococcal sore throat in adults: randomized controlled trial of in-office aids. Can Fam Physician 2007;53:666-671.

Study Design:
Randomized controlled trial (nonblinded)

Synopsis:
Sore throat is among the most common problems seen in primary care practices, and it is evaluated using a variety of strategies. In this study, 37 Canadian family doctors were asked to recruit 20 successive adults with sore throat. The physicians were randomized to use 1 of 4 strategies: usual clinical practice, decision rule only, rapid antigen test only, and clinical decision rule plus rapid antigen test if the decision rule was equivocal. The clinical decision rule was based on the well-validated Centor rule, with 1 point each for fever, swollen glands, absence of cough, and tonsillar exudate, and 1 point subtracted for presence of cough. Interpretation of the rule was as follows: Antibiotics were not recommended for a patient with less than 2 points; antibiotics were recommended for a patient with 3 or 4 points; and no recommendation was made if a patient had 2 points. Between 102 and 170 patients were recruited into each arm and 47% of all patients received a prescription for an antibiotic. The percentage of visits resulting in an antibiotic prescription was 27% for rapid antigen test alone; 38% for clinical decision rule plus rapid antigen test; 55% for clinical rule only; and 58% for usual practice. The difference between the 2 rapid antigen groups and the usual care group was statistically significant, but the difference between clinical rule plus rapid antigen test and the rapid antigen test alone was not. We are not told how many patients had the rapid antigen test in the combined approach group, but presumably it was fewer than in the group where all patients received rapid antigen testing. We are also not told clinical outcomes such as the percentage of patients cured at 2 weeks or the percentage returning because of treatment failure.

Rapid antigen test for yeast more sensitive than wet mount

Clinical Question:
Is a rapid antigen test more accurate than wet mount to diagnose vaginal yeast?

Bottom Line:
The detection of vaginal yeast by rapid antigen testing is feasible for office practice and more sensitive than wet mount. A negative test result, however, is not sensitive enough to rule out yeast and avoid a culture. If this test is made available over the counter, the impact on self-diagnosis and self-treatment with over-the-counter products should be evaluated.

Reference:
Chatwani AJ, Mehta R, Hassan S, Rahimi S, Jeronis S, Dandolu V. Rapid testing for vaginal yeast detection: a prospective study. Am J Obstet Gynecol 2007;196:309.e1-e4.

Study Design:
Diagnostic test evaluation

Synopsis:
Wet mount of vaginal secretions has a sensitivity of only approximately 50% to detect yeast. More accurate testing at the point of care is needed and over-the-counter availability for self-testing is being considered. These investigators recruited 104 women, including 70 who were symptomatic and 34 asymptomatic for yeast vaginitis. Women underwent a vaginal examination performed by a physician who obtained a sample of vaginal secretion, which was tested for yeast by wet mount using 10% potassium hydroxide, by culture, and by a rapid yeast detection test manufactured by Sayyon Diagnostics. Culture was the reference standard. The cost of culture was estimated at $65, the cost of the rapid antigen test was estimated at less than $10. After the examination women were asked to perform their own antigen test for yeast using the instructions provided by the manufacturer. Sensitivity was 73%, with a negative predictive value 82% in the entire group of symptomatic and asymptomatic women. Specificity was 84%, with 16% false-positives. Patient-performed antigen tests had results similar to physician-performed tests. Although it is not specifically stated that the interpretation of the wet mount and antigen test results was blinded with regard to the interpretation of the culture, we may assume this to be the case since wet mount and antigen tests were performed and interpreted by the physician who examined the patient and the culture results were interpreted by laboratory personnel.

Multislice CT is safe and efficient for evaluation of low-risk chest pain

Clinical Question:
Is an algorithm using multi-slice coronary computed tomography a safe and effective diagnostic approach for patients with acute chest pain?

Bottom Line:
Multi-slice coronary computed tomography (MSCT) effectively diagnoses or excludes coronary disease as the cause of acute chest pain in the majority of patients, reducing time to final diagnosis.

Reference:
Goldstein JA, Gallagher MJ, O’Neill WW, et al. A randomized controlled trial of multi-slice coronary computed tomography for evaluation of acute chest pain. J Amer Coll Cardiol 2007;49:863-871.

Study Design:
Randomized controlled trial (nonblinded)

Synopsis:
The authors ompared the safety, diagnostic efficacy, and efficiency of multi-slice computed tomography (MSCT) with standard diagnostic evaluation of low-risk acute chest pain patients. Over 1 million patients have emergency center evaluations for acute chest pain annually, at an estimated diagnostic cost of over $10 billion. Multi-slice computed tomography has a high negative predictive value for exclusion of coronary artery stenoses. So what they did, they randomized patients to MSCT (n = 99) versus SOC (n = 98) protocols. The MSCT patients with minimal disease were discharged; those with stenosis >70% underwent catheterization, whereas cases with intermediate lesions or non-diagnostic scans underwent stress testing. Outcomes included: safety (freedom from major adverse events over 6 months), diagnostic efficacy (clinically correct and definitive diagnosis), as well as time and cost of care. Both approaches were completely (100%) safe. The MSCT alone immediately excluded or identified coronary disease as the source of chest pain in 75% of patients, including 67 with normal coronary arteries and 8 with severe disease referred for invasive evaluation. The remaining 25% of patients required stress testing, owing to intermediate severity lesions or non-diagnostic scans. During the index visit, MSCT evaluation reduced diagnostic time compared with SOC (3.4 h vs. 15.0 h, p < 0.001) and lowered costs (1,586 dollars vs. 1,872 dollars, p < 0.001). Importantly, MSCT patients required fewer repeat evaluations for recurrent chest pain (MSCT, 2 of 99 (2.0%) patients vs. SOC, 7 of 99 (7%) patients; p = 0.10).

Guideline: Mammography optional in women 40-49

Clinical Question:
Should screening mammography be used in women between the ages of 40 years and 49 years?

Bottom Line:
Although few women 50 years of age or older have risks from mammography that outweigh the benefits, the evidence suggests that more women 40 to 49 years of age have such risks.

Reference:
Armstrong K, Moye E, Williams S, Berlin JA, Reynolds EE. Screening mammography in women 40 to 49 years of age: a systematic review for the American College of Physicians. Ann Intern Med 2007;146:516-526.

Study Design:
Practice guideline

Synopsis:
The risks and benefits of mammography screening among women 40 to 49 years of age remain an important issue for clinical practice. The authors evaluated the evidence about the risks and benefits of mammography screening for women 40 to 49 years of age. They looked at only english-language publications in MEDLINE (1966-2005), Pre-MEDLINE, and the Cochrane Central Register of Controlled Trials and references of selected studies through May 2005. Selected only previous systematic reviews; randomized, controlled trials; and observational studies. In addition to publications from the original mammography trials, 117 studies were included in the review. Meta-analyses of randomized, controlled trials demonstrate a 7% to 23% reduction in breast cancer mortality rates with screening mammography in women 40 to 49 years of age. Screening mammography is associated with an increased risk for mastectomy but a decreased risk for adjuvant chemotherapy and hormone therapy. The risk for death due to breast cancer from the radiation exposure involved in mammography screening is small and is outweighed by a reduction in breast cancer mortality rates from early detection. Rates of false-positive results are high (20% to 56% after 10 mammograms), but false-positive results have little effect on psychological health or subsequent mammography adherence. Although many women report pain at the time of the mammography, few see pain as a deterrent to future screening. Evidence about the effect of negative screening mammography on psychological well-being or the subsequent clinical presentation of breast cancer is insufficient.