Cough Suppressive Therapy in Patients With Chronic Cough

In this randomized, placebo-controlled, interventional study on chronic cough a non-pharmacological cough suppressive therapy is the intervention to be studied, with a control group receiving treatment consisting of general healthy lifestyle advice. The following data will be collected before, after and up to six months after treatment: Standardized questionnaires for diagnosis of background factors, Leicester Cough Questionnaire (LCQ), Work Ability Index (WAI), and cough frequency as well as lung function and biomarkers. The primary treatment effect measurement will be changes in chronic cough-related quality of life, measured by the Leicester Cough Questionnaire (LCQ).

The study will be carried out in collaboration between respiratory physicians, clinical physiologists, physiotherapists, speech- and language therapists and gastroenterologists. The primary hypothesis of the planned study is: The cough suppressive therapy improves chronic cough-related quality of life and work ability, and is sustained over six months after treatment. The secondary hypotheses of the planned study are: Treatment of chronic cough by the cough suppressive therapy can reduce cough frequency (measured by an automated cough detector), airway inflammation and airway resistance. Baseline differences in clinical findings, biomarkers and physiologic measurements predict different treatment effects. The following data will be collected before and after treatment: Standardized questionnaires for diagnosis of background factors and cough duration, LCQ, WAI, questions on sick leave days, voice disturbance questionnaire. Physiological measurements: Spirometry with reversibility test, impulse oscillometry before and after provocation with hypertonic saline inhalation. 24 hours cough frequency analysis, voice analysis. Biomarkers: Fractional exhaled nitric oxide (FeNO), blood-eosinophils and eosinophil cationic protein in serum, proteomics in particles in exhaled air (PExA)

The cough suppressive therapy consists of four one-to-one treatment sessions, 45 minutes per session, over a 2 months period. The sessions include patient education about chronic cough; negative effects of repeated cough as well as patient education of voluntary control of cough; identification of cough triggers and learning cough suppression techniques, and psychoeducational counselling including patient self-motivation, repetition of aims and techniques, behavior modification regarding over-awareness of the need to cough. The sessions will be conducted by a specially trained physiotherapist or speech and language therapist. All components of the cough suppressive therapy will be delivered to each participant but the focus and emphasis on individual techniques will be individually tailored for each participant, determined by the physio- or speech and language therapist together with the participant.

The Healthy lifestyle instructions consists of four one-to-one treatment sessions, 30 minutes per session, over a 2 months period. The sessions will be conducted by a specially trained physiotherapist or speech and language therapist. The sessions include patient education and motivational conversation about healthy eating habits, physical activity, stress and relaxation.

The cough suppressive therapy based on the treatment regime "Physiotherapy, and speech and language therapy intervention for patients with refractory chronic cough (PSALTI) developed by S. Chamberlain et al (Thorax. 2017 Feb;72(2):129-136).

The general healthy lifestyle instructions are based on the recommendations from the The Public Health Agency of Sweden.

Leicester Cough Questionnaire (LCQ) is an English-born self-reporting quality of life measure of chronic cough,

WAI is a questionnaire, which serves to conduct a self-assessment. The focus is on the employees and their work ability assessed by themselves

Change from baseline inflammation biomarkers (eosinophil count) in blood at one week after completed intervention

Inclusion Criteria: Chronic cough (duration >2 months) without a structural lung disease and a normal chest X-ray, which have failed pharmacological treatment. Being able to understand the swedish language. Exclusion Criteria: Pulmonary abnormalities on a chest X-ray, structural lung disease, or chronic obstructive pulmonary disease (COPD) of spirometry stage Global Initiative for Obstructive Lung Disease (GOLD) 2 or higher. Smoking under the last three months. Ongoing or recent treatment with angiotensin-converting enzyme (ACE) inhibitor Active aspiration, vocal cord nodules or upper respiratory tract infection in the previous 4 weeks.