What is the most likely indicator of asthma in a patient with recurrent upper respiratory tract infections (URTI), wheezing when playing, and a family history of asthma?

Most Likely Indicator of Asthma in This Clinical Scenario

The wheezing triggered by physical activity (exercise-induced bronchospasm) is the most likely indicator of asthma in this patient.

Diagnostic Reasoning

Why Exercise-Induced Wheezing is Most Specific

Wheezing provoked by exercise is a hallmark feature of asthma and represents variable airflow obstruction triggered by a specific stimulus, which is characteristic of the disease 1. The British Thoracic Society guidelines explicitly state that asthma symptoms are "provoked by triggers including exercise" and that this pattern is a defining feature of the condition 1.

• Exercise-induced bronchospasm demonstrates the key pathophysiologic feature of asthma: reversible airway hyperresponsiveness 1
• This symptom has higher specificity for asthma compared to other presenting features 1
• The European Respiratory Society found that wheeze has a sensitivity of 0.55-0.86 and specificity of 0.64-0.90 for asthma diagnosis, making it reasonably specific when present 1

Why Other Features Are Less Specific

Recurrent URTIs are common in childhood and do not specifically indicate asthma:

• Viral respiratory infections are the most common trigger for asthma exacerbations in children, but they occur frequently in all children, not just those with asthma 2
• Recurrent URTIs alone have poor specificity for asthma diagnosis 1
• Many children with recurrent infections never develop asthma 1

Family history, while important, is a risk factor rather than a diagnostic feature:

• Family history of atopy is "the most important clearly defined risk factor for atopy in children" but does not confirm the diagnosis 1
• It increases the probability of asthma but many children with positive family history never develop the disease 3
• The British Thoracic Society considers family history as "additional information which may contribute towards a clinical suspicion" rather than a diagnostic criterion 1

Normal chest X-rays are expected in asthma:

• Chest X-rays are typically normal in asthma between exacerbations 1
• Normal imaging does not increase or decrease the likelihood of asthma diagnosis 1
• This finding has no discriminatory value for asthma diagnosis 1

Clinical Application

The combination of exercise-induced wheeze with family history creates a strong clinical picture:

• When exercise-induced symptoms are combined with family history and recurrent respiratory symptoms, the Asthma Predictive Index suggests high risk for persistent asthma 4
• The presence of wheeze triggered by a specific stimulus (exercise) is more diagnostically valuable than non-specific symptoms like cough or recurrent infections 1

Common Pitfall to Avoid

Do not diagnose asthma based solely on recurrent respiratory infections or family history without documenting variable airflow obstruction or characteristic symptom patterns like exercise-induced bronchospasm 1. The European Respiratory Society explicitly states that symptoms alone result in misdiagnosis in a considerable number of children 1.