Cough reflex sensitivity improves with speech language pathology management of refractory chronic cough.
BACKGROUND
Speech language pathology is an effective management intervention for chronic cough that persists despite medical treatment. The mechanism behind the improvement has not been determined but may include active cough suppression, reduced cough sensitivity or increased cough threshold from reduced laryngeal irritation. Objective measures such as cough reflex sensitivity and cough frequency could be used to determine whether the treatment response was due to reduced underlying cough sensitivity or to more deliberate control exerted by individual patients. The number of treatments required to effect a response was also assessed.


OBJECTIVE
The aim of this study was to investigate subjective and objective measures of cough before, during and after speech language pathology treatment for refractory chronic cough and the mechanism underlying the improvement.


METHODS
Adults with chronic cough (n = 17) were assessed before, during and after speech language pathology intervention for refractory chronic cough. The primary outcome measures were capsaicin cough reflex sensitivity, automated cough frequency detection and cough-related quality of life.


RESULTS
Following treatment there was a significant improvement in cough related quality of life (Median (IQR) at baseline: 13.5 (6.3) vs. post treatment: 16.9 (4.9), p = 0.002), objective cough frequency (Mean +/- SD at baseline: 72.5 +/- 55.8 vs. post treatment: 25 +/- 27.9 coughs/hr, p = 0.009), and cough reflex sensitivity (Mean +/- SD log C5 at baseline: 0.88 +/- 0.48 vs. post treatment: 1.65 +/- 0.88, p < 0.0001).


CONCLUSIONS
This is the first study to show that speech language pathology management is an effective intervention for refractory chronic cough and that the mechanism behind the improvement is due to reduced laryngeal irritation which results in decreased cough sensitivity, decreased urge to cough and an increased cough threshold. Speech language pathology may be a useful and sustained treatment for refractory chronic cough.


BACKGROUND
Australian New Zealand Clinical Trials Register, ACTRN12608000284369.
Ryan
Nicole M
NM
Centre for Asthma and Respiratory Diseases, School of Medicine and Public Health, The University of Newcastle, Newcastle, 2308, NSW, Australia. Nicole.Ryan@newcastle.edu.au.
Vertigan
Anne E
AE
Bone
Sarah
S
Gibson
Peter G
PG