Cough

Question 1

DDx of cough

Answer 1

Chronic upper airway cough syndrome (postnasal drip)
Chronic sinusitis
GORD
ACE-I coughs
Vocal cord dysfunction (inducible laryngeal obstruction)
Eosinophilic bronchitis
Cough variant asthma

Question 2

What is the definition of chronic cough?

Reference: 2020 ERS guideline on Dx & Mx of chronic cough in adults and children
https://doi.org/10.1183/ 13993003.01136-2019

Answer 2

Cough lasting ≥8w

Question 3

What are the phenotypes of chronic cough?

Answer 3

1) Asthmatic cough/ eosinophilic bronchitis
Ix:
- sputum eosinophil >3% – most accurate but not readily available
- FeNO – but no consensus re cut-off value
- Blood eosinophilia >0.3cells/microL – as surrogate to indicate eosinophilic airway inflammation
- Spirometry

2) Reflux cough

3) Post nasal drip syndrome/ Upper airway cough syndrome (UACS)

4) Iatrogenic cough
Meds involved: ACEi, bisphosphonate, CCB, Latanoprost eye drop

5) Chronic refractory cough/ Idiopathic chronic cough
= chronic cough despite thorough Ix and Rx
Rx: Neuromodulatory drugs: Opioid (most effective is morphine), Gabapentine (less effective than opioid with more SE)

6) Chronic cough in other diseases
e.g. lung cancer, infection, chronic bronchitis

7) Chronic cough caused by tobacco/ nicotine
- Studies have shown that healthy smokers have suppressed cough reflex sensitivity  may explain the transient increase in cough within 1m after smoking cessation

Question 4

What is the approach to assessing cough?

Answer 4

1) Hx taking
- Cough duration/ impact/ triggers/ assoc Sx
- FHx
- Cough score (using visual analogue score, Hull Airway Reflux Questionnaire HARQ)
- Risk factors: ACEi, smoking, OSA

2) Examination
- Throat, chest, ear

3) Ix
- Spirometry
- CXR
- Sputum eosinophil (>3% suggestive of eosinophilic bronchitis)
- FeNO – but no clear cut off point
- Blood eosinophilia >0.3cells/microL – as surrogate to indicate eosinophilic airway inflammation
- Sputum AFB/ C&S
- Additional:
i) HRCT: not recommended if CXR & examination normal
ii) Bronchoscopy
iii) Laryngoscopy
iv) High resolution oesophageal manometry
v) Methacholine challenge

Question 5

Mx and monitoring in chronic cough

Answer 5

1) Mx:
- Stop risk factors
- Initiate high dose of ICS (stop if not responding in 2-4w)
- Initiate LTRA esp in eosinophilic bronchitis/ asthma
- Initiate PPI if with peptic Sx
- Initiate antihistamine if UACS
2) Monitoring
- If there is improvement, continue Rx for 3m then attempt to withdraw
- If no improvement:
Consider promotility meds: e.g. macrolide/ metoclopramide/ domperidone
Consider neuromodulators e.g. opioid (slow-release morphine 5-10mg BD), pregabalin, gabapentin
Consider non-pharmacological Rx: cough control therapy