Table 1.
The utility of spirometry, chest X-ray (CXR), chest computed tomography (CT) scan, flexible bronchoscopy, and further investigations to approach possible causes of chronic cough in children.
| Suspected Cause of Chronic Cough | Initial Investigations * (Recommended for All) | Additional Investigations * (Recommended as Appropriate) | |||
|---|---|---|---|---|---|
| Spirometry | CXR | Chest CT Scan | Flexible Bronchoscopy | Suggested Further Investigation | |
| Asthma [11,12] | To diagnose and monitor airflow obstruction | Likely normal, when no exacerbation | - | - | FeNO, AHR tests, RAST, Therapeutic trial |
| PBB [13] | Likely normal, but monitor disease progression | To identify comorbidity and/or complication | + | + | Therapeutic trial, Respiratory microbiology |
| Bronchiectasis [14] | Findings can vary but monitor disease progression | To identify comorbidity and/or complication | +++ | +++ | Sweat test, immune function tests |
| Cystic fibrosis [15] | Findings can vary but monitor disease progression | To identify comorbidity and/or complication | +++ | +++ | Sweat test, genetic tests |
| Foreign body inhalation [16,17] | May aid in diagnosis: airway obstruction | To identify radio-opaque foreign body and/or air-trapping | +++ | +++ | Rigid bronchoscopy |
| Tracheomalacia [18] | May aid in diagnosis: the ‘knee’ pattern on flow–volume loop | Likely normal, but identify comorbidity and/or complication | + | +++ | Optional to perform dynamic airway CT scan |
| Extrinsic airway compression [19] | Aid for diagnosis: airflow obstruction on flow–volume loop | To identify abnormal intra-thoracic structure | +++ | ++ | Barium swallow |
| Upper airway cough (postnasal drip, rhinitis, rhinosinusitis) [20] | Likely normal | Likely normal | - | - | Allergy tests, therapeutic trial |
| Tracheo-oesophageal fistula [21] | Not applicable for infant presentation | To identify chronic aspiration | + | +++ | Barium swallow, EGDS |
| GORD [22] | Likely normal, unless co-existent with asthma | To identify chronic aspiration | - | +/- | pH/multimodal monitoring, EGDS |
| Chronic infections [23,24] | Findings can vary but monitor disease progression | To identify abnormal lung parenchyma and mediastinum | +++ | +++ | Respiratory microbiology, blood tests |
| Interstitial lung diseases [25,26,27] | Likely restriction or mixed obstruction-restriction in advanced stages | To identify diffuse lung lesions | +++ | ++ | BAL cytology, tissue biopsy, immunology, genetic tests |
| Psychogenic cough [28] | Likely normal | Likely normal | - | - | AHR tests, RAST, psychosocial evaluation, and if possible organic cuases are excluded |
| Cardiovascular-related conditions [29] | Likely normal or non-specific | To identify abnormal intra-thoracic structure | ++ | +/- | ECG, cardiac catheterization |
* The utility of investigation is based on either experts’ opinion or clinical practice guidelines: +++ = definitely beneficial, ++ = probably beneficial, + = possibly beneficial, +/- = unclear benefit, - = unlikely beneficial. FeNO = fractional exhaled nitric oxide, AHR = airway hyperreactivity, PBB = protracted bacterial bronchitis, GERD = gastro-esophageal reflux, EGDS = esophagogastroduodenoscopy, BAL = bronchoalveolar lavage, ECG = electrocardiogram.