When should a chest x-ray be ordered for a patient presenting to a general practice in New Zealand with symptoms of a lower respiratory tract infection?

From the Guidelines

In New Zealand general practice, a chest x-ray should be ordered for patients with lower respiratory tract infection symptoms who have risk factors or concerning clinical features, as identified by the most recent and highest quality study 1. The decision to order a chest x-ray is guided by the presence of specific clinical features and risk factors, rather than routine use for all patients with lower respiratory tract infections.

• Key risk factors and clinical features that warrant a chest x-ray include:
  • Patients over 65 years
  • Smokers
  • Significant comorbidities (such as COPD, heart failure, or immunosuppression)
  • Persistent symptoms despite appropriate treatment
  • Hemoptysis
  • Suspected pneumonia
  • Abnormal chest examination findings
• A chest x-ray is also indicated when symptoms persist beyond 2-3 weeks, when there are recurrent infections, or when there is clinical suspicion of underlying pathology such as malignancy or tuberculosis, as suggested by the guidelines for community-acquired pneumonia 1. The rationale for selective chest x-ray use is to identify complications or underlying conditions that may require different management approaches while avoiding unnecessary radiation exposure and healthcare costs for uncomplicated infections, as supported by the study published in Chest in 2019 1. Most uncomplicated lower respiratory tract infections in otherwise healthy adults can be managed without imaging, as clinical assessment is often sufficient for diagnosis and treatment planning. If ordering a chest x-ray, both posteroanterior and lateral views are typically recommended for comprehensive evaluation, as outlined in the guidelines for the management of adults with community-acquired pneumonia 1.

From the Research

Ordering a Chest X-ray in General Practice in New Zealand

When a patient presents to a general practice in New Zealand with symptoms of a lower respiratory tract infection, the decision to order a chest x-ray should be based on clinical judgement and the patient's specific symptoms and risk factors.

• The study by 2 found that routine chest radiography does not affect the clinical outcomes in adults and children presenting to a hospital with signs and symptoms suggestive of a lower respiratory tract infection.
• However, the same study found that chest radiographs may be beneficial in a subgroup of patients with an infiltrate on their radiograph, with a reduction in length of illness and duration of symptoms.
• Another study by 3 found that magnetic resonance imaging (MRI) is an accurate and effective method for diagnosing outpatient pneumonia, with better accuracy compared to chest radiography.
• The study by 4 found that antibiotics are of limited overall clinical benefit for uncomplicated lower respiratory tract infection, but there is uncertainty about their effectiveness for patients with features associated with higher levels of antibiotic prescribing.
• The study by 5 recommends that diagnosis of community-acquired pneumonia (CAP) is based on symptoms and imaging study results, and that ultrasonography is more accurate than chest x-rays.
• The study by 6 found that symptoms, signs, erythrocyte sedimentation rate, and C-reactive protein can be used to diagnose pneumonia in acute lower respiratory tract infection, and that a prediction rule for low-risk patients can help reduce unjustified antibiotic prescribing.

Indications for a Chest X-ray

A chest x-ray may be indicated in the following situations:

• Patients with severe symptoms or high-risk features, such as older age, underlying comorbidities, or immunosuppression.
• Patients with suspected pneumonia or other complications of lower respiratory tract infection.
• Patients who do not respond to initial treatment or have worsening symptoms.
• Patients with a history of significant comorbidities, as they may be more likely to benefit from antibiotics and a chest x-ray may help guide treatment decisions.

Considerations for General Practice in New Zealand

In general practice in New Zealand, the decision to order a chest x-ray should be based on clinical judgement and the patient's specific symptoms and risk factors.

• GPs should consider the patient's medical history, physical examination, and laboratory results when deciding whether to order a chest x-ray.
• GPs should also consider the potential benefits and harms of chest x-ray, including the risk of radiation exposure and the potential for false-positive or false-negative results.
• The use of clinical prediction rules, such as the one developed by 6, may help GPs identify low-risk patients who do not require a chest x-ray or antibiotics.