Cough desensitization treatment for patients with refractory chronic cough: results of a second pilot randomized control trial.

OBJECTIVE: The purpose of this study was to collect pilot efficacy data on a novel treatment for refractory chronic cough (RCC), which we call cough desensitization treatment (CDT). DESIGN AND METHODS: In this parallel cohort, sham-controlled, randomized controlled trial, 21 adults with RCC were randomly assigned to 12 sessions of either CDT (progressive doses of aerosolized capsaicin while behaviorally suppressing cough; n = 11) or a sham treatment (repeated exposure to aerosolized saline; n = 9). The Leicester Cough Questionnaire (LCQ) was the primary outcome measure. Perceived cough severity with a visual analogue scale and cough challenge testing (for measuring cough-reflex sensitivity) were secondary outcome measures. Data were analyzed with mixed effects linear regression and follow-up contrasts. RESULTS: Results on all measures favored CDT. Excluding one sham participant, whose baseline LCQ scores were deemed unreliable, mean change in LCQ at 3-weeks post treatment was 6.35 and 2.17 in the CDT and sham groups, respectively. There was moderate to strong evidence of a greater improvement in the CDT group in total LCQ score (p = .058) and LCQ Psychological domain (p = .026) and Physical domain (p = .045) scores. Strong evidence was found for a greater reduction in urge-to-cough during CCT in the CDT group (p = .037) and marginal for a reduction in the capsaicin cough-reflex sensitivity (p = .094). There was weak evidence of a greater reduction in cough severity in the CDT group (p = .103). DISCUSSION: Although the study is limited due to the small sample size, the data provide additional evidence supporting further research on CDT. CDT resulted in a greater change in the primary efficacy measure (LCQ) than both pharmaceutical and behavioral treatments currently found in the literature. TRIAL REGISTRATION: This trial (NCT05226299) was registered on Clinicaltrials.gov on 07/02/2022.

Normative Values for the Leicester Cough Questionnaire in Healthy Individuals.

INTRODUCTION: The primary self-assessment questionnaire used for patients with chronic cough is the Leicester Cough Questionnaire (LCQ). The LCQ is a validated questionnaire that ranges in total score from 3 to 21. While it is known that a higher score on the LCQ reflects a better quality of life, normative data have not been reported for this questionnaire. OBJECTIVE: The purpose of this study was to determine normative LCQ scores on a healthy population without cough. METHODS: The LCQ was distributed via electronic survey to the authors' universities, professional affiliation email lists, and personal contacts. Participants were included if they were at least 18, nonsmokers, and without abnormal cough, without pulmonary disease, and without neurological disease. Participants answered questions regarding age, gender, and race/ethnicity, and completed the 19 LCQ questions. RESULTS: One hundred forty-three (118 women) LCQ responses were analyzed. Average participant age was 47 years (SD = 13) and 133 (93%) were Caucasian. The mean LCQ Total score was 20.23 (SD = 0.85) with scores ranging from 17.05 to 21. CONCLUSIONS: This study determined the following LCQ scores should be considered normal threshold scores: Total score - 17.68, Physical domain - 5.36, Psychological domain - 5.81, and Social domain - 6.06. The findings of this study will assist clinicians in determining severity of cough impact on quality of life using the LCQ. Further research is needed to ensure more complete participant demographic representation.

Cough desensitization treatment: A randomized, sham-controlled pilot trial for patients with refractory chronic cough.

BACKGROUND: The purpose of this study was to determine feasibility of treating refractory chronic cough (RCC) with progressive doses of capsaicin paired with cough suppression. METHODS: In this sham-controlled, parallel RCT, 14 adults with RCC were randomly assigned to either behavioral cough suppression therapy (BCST) plus 6 treatment sessions involving exposure to nebulized capsaicin in progressively larger concentrations while actively suppressing cough (n = 8), or BCST plus 6 sessions of exposure to a single subthreshold dose of capsaicin (sham; n = 6). The Leicester Cough Questionnaire (LCQ) was the primary outcome measure. Urge-to-cough (UTC) testing, measuring both UTC and cough frequency, served as secondary outcome measures. Data was analyzed with mixed effects linear regression and follow-up contrasts. RESULTS: Results on all measures favored the treatment group; however, there was only strong evidence of a difference in treatment effect on cough frequency during UTC testing. Mean change in LCQ at 3-weeks post treatment was 2.95 and 1.75 (p = .23), in the treatment and sham groups, respectively. Cough frequency during UTC testing reduced by 97% and 56% (p < .0001) at three weeks post, respectively. Within-group comparisons revealed strong evidence of change in the treatment group (p < .001) and moderate evidence of a change in the sham group (p = .08) in LCQ. CONCLUSIONS: Conclusions from this study are limited due to the very small sample size; however, the study provides feasibility and proof-of-concept evidence to support further investigation of treating RCC with repeated exposure to nebulized capsaicin paired with BCST.

Evaluation and Management Outcomes and Burdens in Patients with Refractory Chronic Cough Referred for Behavioral Cough Suppression Therapy.

PURPOSE: The purpose of this study was to investigate the typical symptoms and medical management characteristics of adult patients with refractory chronic cough (RCC) who are referred to speech-language pathology (SLP) for behavioral cough suppression therapy (BCST) in order to estimate cost-effectiveness and efficiency of current practice patterns for this population. METHODS: One hundred sixty-four (164) patients with RCC referred for BCST were surveyed. Patients completed an initial survey at BCST onset related to symptom pattern and prior treatment, including the Leicester Cough Questionnaire (LCQ). Every four to six weeks patients completed follow-up surveys to assess their response to BCST. RESULTS: Mean age was 58 years (83.5% women). The majority of patients reported their cough began two or more years prior to BCST. Approximately half (49%) reported seeing four or more physicians (including primary care physicians) and being prescribed four or more medications (57%) prior to BCST. Medications targeting post-nasal drip (72%), reflux (70%), asthma (56%), and allergies (56%) were most commonly prescribed. BCST resulted in a clinically significant improvement in 70.1% of participants. The mean change in LCQ for those who improved with BCST was 6.61. Over half (58%) reported they were quite satisfied to completely satisfied with their treatment response. The average time from enrollment to study completion was 64 days. CONCLUSION: The results of this study suggest early intervention with BCST may be a cost-effective and efficient option for patients with RCC.