Etiology of Chronic Cough

Advancing science is broadening our understanding of the potential mechanisms of

Advancing Science Is Broadening Our Understanding of the Potential Mechanisms of Chronic Cough
Etiology of Chronic Cough

Both animal and human studies support the science used to illustrate pathways in this figure. Clinical significance of animal data is unknown.1,4

These potential mechanisms differ from the protective-cough reflex, which is important for clearing the airways of inhaled particles.1,5,7

These Potential Mechanisms Differ From the Protective-Cough Reflex, Which Is Important for Clearing the Airways of Inhaled Particles

These potential mechanisms differ from the protective-cough reflex, which is important for clearing the airways of inhaled particles.1,5,7

These Potential Mechanisms Differ From the Protective Cough Reflex, Which Is Important for Clearing the Airways of Inhaled Particles

Cough hypersensitivity is a common characteristic in patients with chronic cough2,8

Learn more about evolving scientific research on potential mechanisms of chronic cough2

These Potential Mechanisms Differ From the Protective Cough Reflex, Which Is Important for Clearing the Airways of Inhaled Particles

Both mechanical and chemical stimuli within the airways can evoke coughing.1

—Mazzone et al, Physiological Reviews, 2016

The 2017 American College of Chest Physicians (CHEST) Expert Panel published updated clinical guidelines THAT INCLUDE INFORMATION for THE management OF chronic cough9

The guidelines recommend following the steps summarized below:

Conduct an initial investigation of patients with chronic cough (>8 weeks) to assess patient history, which includes any red flags (shown below), occupational and environmental issues, travel exposures, physical exam, and chest radiograph. Always consider smoking history, medications known to cause cough, and whether the cause of cough suggests a life-threatening condition.9

In patients whose initial assessment does not reveal factors that may contribute to cough, further investigation into common underlying conditions (eg, asthma, GERD, UACS [postnasal drip], NAEB) is needed.9

  • Other investigations may be considered including swallow evaluations, sinus imaging, cardiac workup, and occupation assessments9

GERD, gastroesophageal reflux disease; UACS, upper airway cough syndrome; NAEB, nonasthmatic eosinophilic bronchitis.

If cough persists despite appropriate investigation and treatment for each diagnosis or suspected diagnosis, consider referral to a cough clinic for investigation of refractory chronic cough or unexplained chronic cough.9

What are potential red flags when assessing patients presenting with chronic cough?

Red flags include9:

  • HemoptysisHemoptysis
  • Smoker >45 With a New Cough, Change in Cough, or Coexisting Voice DisturbanceSmoker >45 years with a new cough, change in cough, or coexisting voice disturbance
  • Adults Aged 55-80 Years: 30 pack-year Smoking History and Current Smoker or Quit <15 Years AgoAged 55-80 years: 30 pack-year smoking history, and current smoker or quit <15 years ago
  • Prominent Dyspnea, Especially at Rest or at NightProminent dyspnea, especially at rest or at night
  • HoarsenessHoarseness
  • Systemic Symptoms, Including Fever, Weight Loss, and/or Peripheral Edema With Weight GainSystemic symptoms, including fever, weight loss, and/or peripheral edema with weight gain
  • Trouble Swallowing When Eating or DrinkingTrouble swallowing when eating or drinking
  • VomitingVomiting
  • Recurrent PneumoniaRecurrent pneumonia
  • Abnormal Respiratory Exam and/or Abnormal Chest Radiograph Coinciding With Duration of CoughAbnormal respiratory exam and/or abnormal chest radiograph coinciding with duration of cough

Important reminders9:

Check for red flags (shown above) and address them

  • Optimize therapy for each diagnosis
  • Check compliance during regularly scheduled and frequent follow-ups (assess for patient barriers to enactment or receipt of instructions)
  • Due to the possibility of multiple causes, maintain all partialIy effective treatment
  • Routinely assess for environmental and occupational factors
  • Routinely assess cough severity and HRQoL with validated tools
  • Routinely follow up with patient in 4-6 weeks
  • Consider a referral to a cough clinic for refractory cough

References: 1. Mazzone SB, Undem BJ. Physiol Rev. 2016;96:975-1024. 2. Mazzone SB et al. Lancet Respir Med. 2018;6:636-646. 3. Bonvini SJ, Belvisi MG. Pulm Pharmacol Ther. 2017;47:21-28. 4. West PW et al. Am J Respir Crit Care Med. 2015;192:30-39. 5. Smith JA, Badri H. J Allergy Clin Immunol Pract. 2019;7:1731-1738. 6. Canning BJ et al. Chest. 2014;146:1633-1648. 7. Canning BJ. Pulm Pharmacol Ther. 2011;24:295-299. 8. Roe NA et al. Curr Otorhinolaryngol Rep. 2019;7:116-128. 9. Irwin RS et al. Chest. 2018;153:196-209.