Serum Procalcitonin Levels in Acute Respiratory Illness
Serum Procalcitonin Levels in Acute Respiratory Illness
Background: Clinical diagnosis of pneumonia is difficult and chest radiographs often indeterminate, leading to incorrect diagnoses and antibiotic overuse.
Objective: To determine if serum procalcitonin (ProCT) could assist in managing patients with respiratory illness and indeterminate radiographs.
Design: Subjects were prospectively enrolled during 2 consecutive winters.
Setting: A 520-bed hospital in Rochester, NY.
Patients: Five hundred twenty-eight adults admitted with acute respiratory illness were enrolled.
Measurements: Serum ProCT, admission diagnoses, and chest radiographic findings were used to derive receiver operating characteristics curves to assess predictive accuracy of ProCT for the presence of infiltrates.
Results: Subjects with pneumonia had higher ProCT (median 0.27 ng/ml) than those with exacerbations of chronic obstructive pulmonary disease (0.08 ng/ml), acute bronchitis (0.09 ng/ml), or asthma (0.06 ng/ml). ProCT had moderate accuracy for the presence of infiltrates (area under curve [AUC] 0.72), when indeterminate radiographs were independently classified as infiltrates by a pulmonologist evaluating patients.
Conclusions: ProCT may be useful in diagnosing pneumonia when chest radiographs are indeterminate. Journal of Hospital Medicine 2013;8:61–67. © 2012 Society of Hospital Medicine
Pneumonia is a common reason for hospitalization and major rationale for administration of antibiotics in the United States. Management guidelines for patients hospitalized with community-acquired pneumonia recommend early antibiotic therapy. Quality measures adopted by the Centers for Medicare and Medicaid Services include antibiotic administration within 6 hours of presentation, based on a relationship between early administration and improved survival. However, this imperative has been associated with an increase in incorrect diagnoses of pneumonia. While pneumonia diagnosis would seem straightforward, clinical findings frequently do not differentiate pneumonia from other respiratory illnesses. Thus, an infiltrate on chest radiographs (CXR) is commonly used to assign an admitting diagnosis of pneumonia. However, radiographic reports are often inconclusive and frequently fail to discriminate pneumonic infiltrates from atelectasis, edema, small pleural effusions, or chronic abnormalities. In cases of uncertainty, physicians invariably initiate antibiotics, even when the illness is more consistent with viral bronchitis or asthma, resulting in unnecessary antibiotic use. Previously considered relatively harmless, antibiotic complications can be lethal, and excessive use promotes antimicrobial resistance.
Procalcitonin (ProCT), a calcitonin precursor normally produced in the thyroid and lungs, is secreted by cells throughout the body in response to bacterial infections. Elevated ProCT is used to screen patients with suspected bacterial infection and predict mortality in critically ill patients. Recently, European investigators have used ProCT to guide more selective antibiotic use in patients with symptoms of lower respiratory tract infection (LRTI), including pneumonia. However, few reports describe the relationship of ProCT with radiographic features in hospitalized patients with LRTI, and none focus on patients with indeterminate radiographic readings.
We sought to determine if elevated serum ProCT in adults hospitalized with LRTI symptoms correlates with the clinical diagnosis of pneumonia and definitive infiltrates on CXRs. We specifically assessed ProCT as a diagnostic marker of pneumonia to augment clinical judgment in patients when radiographic findings are indeterminate.
Abstract and Introduction
Abstract
Background: Clinical diagnosis of pneumonia is difficult and chest radiographs often indeterminate, leading to incorrect diagnoses and antibiotic overuse.
Objective: To determine if serum procalcitonin (ProCT) could assist in managing patients with respiratory illness and indeterminate radiographs.
Design: Subjects were prospectively enrolled during 2 consecutive winters.
Setting: A 520-bed hospital in Rochester, NY.
Patients: Five hundred twenty-eight adults admitted with acute respiratory illness were enrolled.
Measurements: Serum ProCT, admission diagnoses, and chest radiographic findings were used to derive receiver operating characteristics curves to assess predictive accuracy of ProCT for the presence of infiltrates.
Results: Subjects with pneumonia had higher ProCT (median 0.27 ng/ml) than those with exacerbations of chronic obstructive pulmonary disease (0.08 ng/ml), acute bronchitis (0.09 ng/ml), or asthma (0.06 ng/ml). ProCT had moderate accuracy for the presence of infiltrates (area under curve [AUC] 0.72), when indeterminate radiographs were independently classified as infiltrates by a pulmonologist evaluating patients.
Conclusions: ProCT may be useful in diagnosing pneumonia when chest radiographs are indeterminate. Journal of Hospital Medicine 2013;8:61–67. © 2012 Society of Hospital Medicine
Introduction
Pneumonia is a common reason for hospitalization and major rationale for administration of antibiotics in the United States. Management guidelines for patients hospitalized with community-acquired pneumonia recommend early antibiotic therapy. Quality measures adopted by the Centers for Medicare and Medicaid Services include antibiotic administration within 6 hours of presentation, based on a relationship between early administration and improved survival. However, this imperative has been associated with an increase in incorrect diagnoses of pneumonia. While pneumonia diagnosis would seem straightforward, clinical findings frequently do not differentiate pneumonia from other respiratory illnesses. Thus, an infiltrate on chest radiographs (CXR) is commonly used to assign an admitting diagnosis of pneumonia. However, radiographic reports are often inconclusive and frequently fail to discriminate pneumonic infiltrates from atelectasis, edema, small pleural effusions, or chronic abnormalities. In cases of uncertainty, physicians invariably initiate antibiotics, even when the illness is more consistent with viral bronchitis or asthma, resulting in unnecessary antibiotic use. Previously considered relatively harmless, antibiotic complications can be lethal, and excessive use promotes antimicrobial resistance.
Procalcitonin (ProCT), a calcitonin precursor normally produced in the thyroid and lungs, is secreted by cells throughout the body in response to bacterial infections. Elevated ProCT is used to screen patients with suspected bacterial infection and predict mortality in critically ill patients. Recently, European investigators have used ProCT to guide more selective antibiotic use in patients with symptoms of lower respiratory tract infection (LRTI), including pneumonia. However, few reports describe the relationship of ProCT with radiographic features in hospitalized patients with LRTI, and none focus on patients with indeterminate radiographic readings.
We sought to determine if elevated serum ProCT in adults hospitalized with LRTI symptoms correlates with the clinical diagnosis of pneumonia and definitive infiltrates on CXRs. We specifically assessed ProCT as a diagnostic marker of pneumonia to augment clinical judgment in patients when radiographic findings are indeterminate.
