Objective Evidence of Asthma
Polyphonic wheezing with exercise (Option A) represents objective evidence of asthma, as it is a cardinal clinical sign that can be directly observed and documented during physical examination. 1
Understanding Objective vs. Subjective Evidence
Objective evidence refers to findings that can be directly observed, measured, or documented by the clinician, rather than symptoms reported by the patient alone. 1
Why Polyphonic Wheezing with Exercise is Objective:
Polyphonic wheeze is a cardinal sign of asthma that is usually diffuse, bilateral, and particularly expiratory, and should be documented in clinical notes when present. 1
Exercise-induced wheezing is highly characteristic of asthma, as the hallmark of asthma includes symptoms that are provoked by triggers including exercise. 1, 2
This finding can be directly auscultated and observed by the clinician during or after exercise challenge, making it objective physical examination evidence. 1
Exercise testing can serve as a diagnostic test, where patients are asked to exercise for six minutes (e.g., running), with measurements taken before, during, and after to document decreased peak flow or wheeze. 1
Why the Other Options Are NOT Objective Evidence:
Normal X-ray between episodes (Option B):
- A normal chest X-ray between episodes is not specific to asthma and can be seen in many intermittent respiratory conditions. 2
- The diagnosis of asthma is clinical and there is no confirmatory radiographic investigation. 1, 2
- Chest radiograph may be needed to exclude alternative diagnoses but is not routinely required for asthma diagnosis. 3
Family history of asthma (Option C):
- Family history is additional information that contributes to clinical suspicion, not objective evidence. 1
- Personal or family history of asthma or other atopic conditions is considered supportive information rather than objective diagnostic evidence. 1
Clinical Context and Pitfalls:
Important caveat: While polyphonic wheeze is objective evidence when present, outside acute episodes, there may be no objective signs of asthma. 1 This is why additional objective testing with spirometry, peak flow variability, or bronchodilator response is typically needed to confirm the diagnosis. 1, 3, 4
The gold standard for objective asthma diagnosis remains spirometry with bronchodilator reversibility testing, which demonstrates airflow obstruction and reversibility (FEV1 increase ≥15% AND ≥200 mL). 3, 4