Since the incorporation of the ACC/ESC guidelines, the diagnosis of ACS has substantially increased. It is critical to distinguish between ACS and NTTE when using these very sensitive biomarkers, because the underlying cause of NTTE usually requires a drastically different therapy than that of ACS; in addition, misdiagnosing a myocardial infarction may lead to potentially harmful diagnostic studies and therapies in the form of coronary angiography, antithrombotics, and antiplatelet agents. Hospitalists should look for ACS when troponin T levels exceed 1.0 ng/mL in the face of normal renal function. Based on their data, the authors present an algorithm for working up ACS and NTTE that takes into consideration the clinical presentation, age, renal function, electrocardiographic changes, and troponin T levels. Though this is a retrospective trial, it provides guidance for a very common clinical scenario. We should be concerned about a patient’s prognosis when we encounter an elevated troponin in a setting of NTTE.
Guiding Antibiotic Therapy for COPD Exacerbations
Stolz D, Christ-Crain M, Bingisser R, et al. Antibiotic treatment of exacerbations of COPD: a randomized, controlled trial comparing procalcitonin-guidance with standard therapy. Chest. 2007 Jan;131(1):9-19.
Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality in the United States. Exacerbations of COPD (ECOPD) that require hospitalization are both common and costly. Though recent literature suggests that antibiotic therapy during exacerbations reduces morbidity and mortality and lowers the lack of response to treatment, controversy persists concerning whether or not these results are applicable to all patients with this condition. Procalcitonin is a protein not typically measurable in plasma. Levels of this protein rise with bacterial infections, but appear to be unaffected by inflammation from other etiologies such as autoimmune processes or viral infections. Measuring procalcitonin levels has already been shown to safely decrease the use of antibiotics in lower respiratory infections.
This single-center trial from Switzerland evaluated consecutive patients admitted from the emergency department with ECOPD. For 226 enrolled patients, symptoms were quantified, sputum was collected, spirometry was measured, and procalcitonin levels were evaluated. Attending physicians chose antibiotics, using current guidelines, for patients randomized to the standard therapy group. In the group randomized to procalcitonin guidance, antibiotics were given according to serum levels. No antibiotics were administered for levels below 0.1 micrograms (mcg)/L; antibiotics were encouraged for levels greater than 0.25 mcg/L. For levels between 0.1 and .25 mcg/L, antibiotics were encouraged or discouraged based on the clinical condition of the patient. The primary outcomes evaluated were total antibiotics used during hospitalization and up to six months following hospitalization. Secondary endpoints included clinical and laboratory data and six-month follow-up for exacerbation rate and time to the next ECOPD.
Procalcitonin guidance significantly decreased antibiotic administration compared with the standard-therapy arm (40% versus 72% respectively; P<0.0001) and antibiotic exposure (RR, 0.56; 95% CI, 0.43 to 0.73; P<0.0001). The absolute risk reduction was 31.5% (95% CI, 18.7 to 44.3%; p<0.0001). No difference in the mean time to the next exacerbation was noticed between the two groups. Clinical and laboratory measures at baseline and through the six-month follow-up demonstrated no significant differences.
Using procalcitonin levels to guide antibiotic therapy for ECOPD is a practice that is exciting and full of promise. Not only could costs be cut by omitting antibiotics for this treatment regimen in select patients, but some pressure will be relieved in terms of decreasing emerging bacterial resistance. Because procalcitonin levels have a lab turn-around time of approximately one hour, this test becomes even more attractive: decisions for treatment can be made while patients are still in the emergency department. On a cautionary note, there is more than one method of testing for procalcitonin levels, and this trial was done at only one center. Before widespread use of this test is applied, these results should be validated in a multicenter trial. In addition, one test should be used consistently for measuring procalcitonin levels.