Diagnostic Criteria for Cough Variant Asthma in a 2-Year-Old with Recurrent URIs
In a 2-year-old with isolated chronic cough and recurrent upper respiratory infections, cough variant asthma is unlikely and should NOT be diagnosed without objective evidence of airway obstruction and documented response to asthma therapy. 1
Critical Diagnostic Principle
Children with chronic cough as the only symptom are unlikely to have asthma and should be investigated according to chronic cough guidelines rather than being empirically treated as asthma. 1 The European Respiratory Society strongly recommends against diagnosing asthma based on symptoms alone, even when classic features are present. 2
Why Cough Variant Asthma is Problematic in This Age Group
Evidence Against the Diagnosis
Airway inflammation studies show that children with isolated chronic cough rarely have asthma-type cellular profiles. 1 Studies examining bronchoalveolar lavage in children with persistent cough found only 3 of 23 had asthma-type airway inflammation. 1
Community studies demonstrate that persistent cough without wheeze differs fundamentally from asthma. 1 Research concluded that "cough variant asthma is probably a misnomer for most children in the community who have persistent cough." 1
Recurrent chest colds and persistent cough without wheeze should not be considered a variant of asthma. 1
Age-Specific Challenges (0-2 Years)
Diagnosis in infants and young children is particularly challenging due to inability to obtain objective lung function measurements. 1
Recurrent wheeze and cough in this age group are commonly associated with viral respiratory infections without representing true asthma. 1, 3
The younger the child, the more other disorders may mimic asthma, including gastroesophageal reflux, cystic fibrosis, and chronic lung disease of prematurity. 1
Diagnostic Criteria IF Cough Variant Asthma is Considered
The diagnosis should only be made after meeting ALL of the following criteria: 1, 4
1. Exclusion of Alternative Diagnoses
Rule out protracted bacterial bronchitis (common cause of chronic cough in preschoolers, diagnosed 3 times more often than in older children). 5
Exclude upper airway cough syndrome, postinfectious cough, gastroesophageal reflux, and foreign body aspiration. 1, 5
Consider that recurrent URIs themselves may explain the cough without asthma being present. 1 Children aged <5 years have 3.8 to 8 acute respiratory infections per year normally. 1
2. Objective Evidence Required
Demonstrate airway hyperresponsiveness through bronchoprovocation testing (though this is rarely feasible in a 2-year-old). 1
Document variable airflow obstruction if possible, though spirometry cannot be performed at age 2. 4
Chest x-ray may be needed to exclude other diagnoses. 1
3. Therapeutic Trial Criteria (Only After Exclusions)
If objective testing is impossible due to age, a therapeutic trial requires: 1, 4
Clear-cut response to moderate-dose inhaled corticosteroids (not just bronchodilators). 4
Relapse of symptoms upon stopping medication. 4
Second response to recommencing treatment. 4
Confirmation by positive response to asthma medications, not just symptom improvement alone. 1
4. Clinical Features Supporting the Diagnosis
Cough should be predominantly dry (not productive). 1
Nocturnal cough lasting more than 2 weeks. 6
Episodes triggered by activity, laughing, crying, or weather changes (not just viral URIs). 3
Recovery from viral URIs takes longer than the usual week. 3
Critical Pitfalls to Avoid
Do NOT diagnose asthma based on cough alone without wheeze. 1 The sensitivity and specificity of cough as a marker for wheeze is poor at 34% and 35% respectively. 1
Do NOT use labels like "reactive airway disease" or "wheezy bronchitis" to avoid proper diagnostic evaluation. 1
Do NOT start empirical inhaled corticosteroids without objective confirmation or proper therapeutic trial criteria. 1, 2
Avoid overdiagnosing asthma in children who have chronic non-specific cough, as these children require no treatment, improve with time, and have normal long-term lung function. 4
Recommended Approach for This 2-Year-Old
Given the recurrent URIs and age, the most likely diagnosis is post-viral cough or protracted bacterial bronchitis rather than cough variant asthma. 5
Consider referral to a pediatric pulmonologist if signs and symptoms are atypical or if there are problems with differential diagnosis. 1
Avoid prolonged inappropriate asthma therapy, but do not miss the opportunity to treat true asthma if present. 1
Monitor for development of wheeze over time, as some children with isolated cough may later develop classic asthma. 4, 6