Prospective Study on the Evaluation, Patient Reported Outcomes and Effectiveness of Treatment for Chronic Cough

Chronic cough is a common troublesome symptom which has a global prevalence of approximately 10%, but with wide variations across continents. The aim of this study is to evaluate the effectiveness of treatment, patient-reported outcomes and burden of disease in patients with chronic cough referred to a specialist clinic. The proposed study will use pre-defined diagnostic criteria, investigations and treatment algorithms such that all recruited patients will undergo the same investigations and follow a set management algorithm. This study will objectively and subjectively assess coughing at baseline and after treatment in a real-world clinical setting. This will allow us to understand the relationship between any objective reduction in cough after treatment, and whether this translates to any significant improvement in subjective questionnaire scores. We will assess the impact of health conditions on lost productivity in monetary units and assess the amount of absenteeism, presenteeism and daily activity impairment attributable to unexplained chronic cough/refractory chronic cough. Finally, a patient survey at the end of the study will evaluate the patients' satisfaction and experience of investigation, management trials and use of questionnaires.

This is a prospective observational single-center study of patients referred to secondary care for investigation and management of explained chronic cough, refractory chronic cough, and unexplained chronic cough. The study will have 4 research visits integrated between standard clinical visits. Patients will be recruited from secondary care clinics. Patient eligibility will be assessed against the study inclusion/exclusion criteria and patients will undergo informed consent in the research centre. Subjects who provide informed consent and are enrolled in the study will undergo screening procedures.

At Visit 1 (screening) data on demographics and medical history will be collected and a complete physical examination will be conducted. Subjects will undergo skin prick testing and spirometry and complete self-reported questionnaires (Leicester Cough Questionnaire, Valuation of Lost Productivity, Work Productivity, Activity, and Impairment, Healthcare Resource Utilization, Reflux Disease Questionnaire, Sino-Nasal Outcome Test, and Global Rating of Change Scale). Subjects will be fitted with a 24-hour cough monitor.

At Visit 2, the 24-hour cough monitor will be removed. Subjects will undergo blood sampling, methacholine challenge, sputum induction, and provide a urine sample.

Between Visits 2 and 3, physicians will provide a single clinical treatment pathway to address the most likely cause of chronic cough. Treatment for chronic cough will be in line with current clinical practice guidelines published by the European Respiratory Society Taskforce on Chronic Cough. Treatment plans will range from 2 weeks to 3 months.

Visit 3 will occur 2 weeks to 3 months following subjects' second clinical visit. Subjects will complete self-reported questionnaires (Leicester Cough Questionnaire, Valuation of Lost Productivity, Work Productivity, Activity, and Impairment, Reflux Disease Questionnaire, Sino-Nasal Outcome Test, and Global Rating of Change Scale) and be fitted with a 24-hour cough monitor.

At Visit 4 the 24-hour cough monitor will be removed. Subjects will undergo blood sampling, sputum induction, and provide a urine sample. Subjects will complete a patient satisfaction survey.

All study procedures will be performed according to local standard operating procedures and be conducted by trained and experienced staff with supervision by medical doctors. Safety will be assessed throughout the study by monitoring for adverse events and serious adverse events.

Eligibility Criteria:
Inclusion Criteria:

1. Aged ≥18-75
2. Patients referred to a specialist primarily with a history of chronic cough (cough lasting \>8 weeks)
3. Normal Chest X-ray
4. No Evidence of Airflow Obstruction

Exclusion Criteria:

1. Subjects who are currently established on treatment and their chronic cough is well controlled.
2. Unable to perform acceptable and reproducible spirometry.
3. Current smoker or ex-smoker with ≥20 pack-year smoking history and abstinence of ≤6 months
4. Symptoms of upper respiratory tract infection in the last 1 month which have not resolved
5. Lower respiratory tract infection or pneumonia in the last 1 month
6. Asthma exacerbation in the previous month requiring an increase or start of an inhaled corticosteroid or oral corticosteroid
7. Significant other primary pulmonary disorders in particular; pulmonary embolism, pulmonary hypertension, lung cancer, cystic fibrosis, significant radiologically proven emphysema, interstitial lung disease or bronchiectasis.
8. Any centrally acting medication within the last 2 weeks which in the view of the investigator could influence the coughing. Any participant who is taking amitriptyline, dextromethorphan, pregabalin, gabapentin or opioids will not be eligible to take part in this study unless they are willing and medically able to withdraw from such medication before the start of visit 1. The reason for this is that centrally-acting medications may influence coughing rates at baseline.
9. History of psychiatric illness, drug or alcohol abuse which may interfere in the participation of the trial.
10. Positive Covid-19 test within 2 weeks of screening visit.