Treatment response trajectories for speech pathology intervention in chronic cough.

Background: Speech pathology intervention is an effective treatment for refractory and unexplained chronic cough (RUCC); however, data regarding treatment outcomes in real-world settings are limited. Similarly, the influence of cough phenotypes on treatment response variability is unknown. This study aimed to 1) identify trajectories of response to speech pathology intervention and 2) determine predictors of treatment response trajectories. Methods: The medical records of 205 participants referred to speech pathology for assessment and management of RUCC were reviewed. Data included demographics, medical comorbidities, appointment dates, Leicester Cough Questionnaire (LCQ) scores and clinical outcome. Participants with three or more LCQ scores were included in the analysis. A growth mixture model was used to estimate participant treatment response trajectories and logistic regression models identified baseline predictors of trajectory membership. Results: Three treatment response trajectory groups were identified: Severe Cough-Slow Response (21%), Severe Cough-Rapid Response (23%) and Moderate Cough-Slow Response (56%). Asthma diagnosis (p=0.034) and baseline LCQ score (p≤0.001) were predictors of trajectory group. Most patients (76%) achieved improvement exceeding the LCQ minimally clinically important difference. Notably, the Severe Cough-Rapid Response group demonstrated marked improvement in LCQ score with a shorter treatment duration (median 56 days). Conclusions: This novel application of trajectory analysis to investigate treatment response to speech pathology intervention in RUCC supports the heterogeneous nature of RUCC. We identified a group with severe cough who demonstrated a faster and greater treatment response. Our findings demonstrate the effectiveness of speech pathology intervention and support further exploration of cough phenotyping.