From the Journals

New CHEST expert panel advice on cough diagnosis


 

FROM THE JOURNAL CHEST®

The CHEST Expert Cough Panel has released two new expert guidelines, one aimed at adult outpatients with a cough likely related to influenza or pneumonia and one for pertussis-associated cough in adults and children.

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Upper and lower respiratory tract infections are a common reason for primary care visits. A cough caused by influenza or pneumonia represents an opportunity to intervene for a significant benefit. The recommendations were published in CHEST®. The panel drafted recommendations based on available evidence and graded them using the CHEST grading system. The grading is based on the strength of the recommendation (either strong or weak) and a rating of the overall quality of the body of evidence. Where available evidence was weak, but guidance was still warranted, a weak suggestion was developed and graded 2C. Recommendations based on consensus in cases of insufficient clinical evidence are labeled “ungraded consensus-based statement.”

Suspected pneumonia or influenza

In adult outpatients with acute cough, the clinical signs of pneumonia include cough, dyspnea, pleural pain, sweating/fevers/shivers, aches and pains, temperature greater than or equal to 38°C, tachypnea, and new and localizing chest examination signs. When pneumonia is suspected to cause acute cough, C-reactive protein (CRP) should be measured. A CRP value higher than 30 mg/L bolsters the case for pneumonia, whereas a CRP value of lower than 10 mg/L, or between 10 mg/L and 50 mg/L in the absence of dyspnea and daily fever, makes pneumonia less likely.

The guidelines recommend against routine measurement of procalcitonin for outpatient adults suspected to have pneumonia. For adults with acute cough and abnormal vital signs believed to be secondary to pneumonia, the guidelines call for a chest x-ray.

Routine microbiological testing need not be performed in suspected pneumonia, but it should be considered if the results could guide or lead to a change in therapy.

When pneumonia is suspected but imaging is unavailable, empiric antibiotics should be used in concordance with local and national guidelines. If imaging turns up negative, antibiotics should not be used. However, if there is no clinical or radiographic evidence of pneumonia, antibiotics should not be used routinely.

Finally, adult patients with acute cough and suspected influenza should begin antiviral treatment within 48 hours of the start of symptoms.

Pertussis

Pertussis has significant morbidity and mortality, with infants being particularly vulnerable, and it is highly contagious. Although antibiotics will not affect the course of the disease, they should be administered as quickly as possible in order to prevent further spread. This puts pressure on the clinician to make a treatment decision before further testing is available.

A prespecified meta-analysis found high sensitivity and low specificity for paroxysmal cough (sensitivity, 93.2%; specificity, 20.6%) and absence of fever (sensitivity, 81.8%; specificity, 18.8%). The study found low sensitivity and high specificity for inspiratory whoop (sensitivity, 29.8%; specificity, 79.5%) and posttussive vomiting (sensitivity, 32.5%; specificity, 77.7%). In children, the review found that posttussive vomiting was moderately sensitive (60.0%) and specific (66.0%).

In adult patients with acute cough (less than 3 weeks’ duration) or subacute cough (3-8 weeks), the new guidelines recommend that physicians consider four key characteristics: the presence of recurrent, prolonged coughing episodes with an inability to breathe during the spell (paroxysmal); posttussive vomiting; inspiratory whooping; and presence of fever.

In acute or subacute cough, if the patient has a fever (body temperature greater than 98.6° F or 37.6° C) or does not have a paroxysmal cough, pertussis is unlikely. On the other hand, posttussive vomiting or an associated inspiratory whooping sound suggests pertussis.

Children with a cough lasting fewer than 4 weeks (acute) should be assessed for paroxysmal cough, posttussive vomiting, and inspiratory whooping. A cough associated with any of these characteristics may be caused by pertussis.

SOURCES: Moore A et al. CHEST. 2019 Jan;155:147-154; Hill A et al. CHEST. 2019 Jan;155:155-167.

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