What is the basis of a bronchitis diagnosis?

From the Guidelines

Bronchitis is diagnosed primarily based on clinical symptoms and physical examination findings, with no routine investigation with chest x-ray, spirometry, peak flow measurement, sputum for microbial culture, respiratory tract samples for viral PCR, serum C-Reactive Protein (CRP) or procalcitonin required for immunocompetent adult outpatients 1. The diagnosis of bronchitis involves evaluating symptoms such as persistent cough (often productive with mucus), chest discomfort, mild fever, fatigue, and shortness of breath. During the physical examination, the doctor will listen to the lungs with a stethoscope to detect abnormal sounds like wheezing or crackling. In most cases of acute bronchitis, laboratory tests or imaging studies are not necessary, as emphasized by the Chest expert panel report in 2020 1. However, for chronic bronchitis, pulmonary function tests may be performed to assess lung function, and a chest X-ray might be ordered to rule out other conditions like pneumonia or lung cancer. Sputum cultures may occasionally be collected if a bacterial infection is suspected, particularly in cases that don't improve with standard treatment or in patients with underlying lung disease, as suggested by the guidelines 1. The diagnosis is often confirmed by the characteristic pattern of symptoms and their duration, with acute bronchitis typically lasting less than three weeks, while chronic bronchitis is defined as a productive cough occurring for at least three months in two consecutive years. Key considerations in the diagnosis include:

• Excluding other differential diagnoses such as pneumonia, the common cold, acute asthma, or an exacerbation of COPD 1
• Evaluating the patient's preexisting health conditions, exposure history, and considering differential diagnoses such as cough variant asthma, acute exacerbation of chronic bronchitis in a smoker, acute exacerbation of bronchiectasis, and acute rhinosinusitis 1
• Avoiding routine prescription of antibiotic therapy, antiviral therapy, antitussives, inhaled beta agonists, inhaled anticholinergics, inhaled corticosteroids, oral corticosteroids, oral NSAIDs or other therapies until such treatments have been shown to be safe and effective at making cough less severe or resolve sooner 1.

From the Research

Basis of Bronchitis Diagnosis

The diagnosis of bronchitis is primarily clinical, relying on the presentation of symptoms rather than diagnostic testing. Key points to consider include:

• Acute bronchitis is characterized by cough due to acute inflammation of the trachea and large airways without evidence of pneumonia 2.
• The differential diagnosis includes exacerbations of preexisting conditions, such as asthma, chronic obstructive pulmonary disease, and heart failure, as well as other causes of acute cough, including pertussis, COVID-19, influenza, and community-acquired pneumonia 3.
• Symptoms of bronchitis typically last about two to three weeks 4, 2.

Diagnostic Considerations

When diagnosing bronchitis, it's essential to:

• Differentiate it from other common diagnoses, such as pneumonia and asthma, which may require specific therapies not indicated for bronchitis 4.
• Consider the presence or absence of colored sputum, which does not reliably differentiate between bacterial and viral lower respiratory tract infections 4.
• Rule out secondary causes for cough, such as pneumonia, and educate patients about the natural course of the disease 2, 5.

Role of Diagnostic Testing

Diagnostic testing is not typically indicated for bronchitis unless there is concern for other potential causes, such as:

• Community-acquired pneumonia 3.
• Influenza or COVID-19 3.
• Pertussis, especially if the cough persists for more than two weeks and is accompanied by symptoms such as paroxysmal cough, whooping cough, and post-tussive emesis 2.