Abstract
BackgroundMany patients with chronic cough respond to treatment with inhaled corticosteroids but it is difficult to predict which patients are likely to respond. The primary aim of the present study was to define the capability of hypertonic saline cough provocation test to predict the responsiveness to inhaled corticosteroids in chronic cough. The secondary aim was to assess the ability of the saline test to monitor the healing of cough during corticosteroid treatment.MethodsForty-three patients with chronic cough were recruited. Before therapy, spirometry, ambulatory peak flow monitoring, nitric oxide measurement, histamine airway challenge, and saline test were performed. Those responding to the first saline test repeated it and the nitric oxide measurement during the subsequent visits. The patients used inhaled budesonide, 400 ug twice daily, for twelve weeks. The treatment response was assessed by Leicester Cough Questionnaire at baseline, and at one, four, and twelve weeks.ResultsSeventy-seven % of the patients demonstrated the minimal important difference in the Leicester Cough Questionnaire indicating a symptomatic response. Neither the response magnitude nor the speed was predicted by the saline test. Histamine challenge showed the strongest predictive ability: The maximal improvement in Leicester Cough Questionnaire total score was 5.08 (3.76 – 6.40) points in the histamine positive and 2.78 (1.55 – 4.01) points in the histamine negative subjects (p = 0.006). Baseline nitric oxide level also associated with the improvement in Leicester Cough Questionnaire total score (p = 0.02). During the treatment, the cough sensitivity to saline gradually decreased among the budesonide responders but not in the non-responders. Nitric oxide levels decreased very rapidly among the responders.ConclusionsSaline test cannot predict the responsiveness to inhaled corticosteroids in chronic cough but it may be utilized to monitor the effect of this treatment.Trial registrationThe study was registered in ClinicalTrials.gov database (KUH5801112). ClinicalTrials.gov Identifier: NCT00859274
Highlights
Many patients with chronic cough respond to treatment with inhaled corticosteroids but it is difficult to predict which patients are likely to respond
There were no significant correlations between Leicester Cough Questionnaire [19] (LCQ) total score or saline CDR and the other tests
Hypertonic saline cough provocation test The test has been described in detail previously [13]
Summary
Many patients with chronic cough respond to treatment with inhaled corticosteroids but it is difficult to predict which patients are likely to respond. The primary aim of the present study was to define the capability of hypertonic saline cough provocation test to predict the responsiveness to inhaled corticosteroids in chronic cough. The secondary aim was to assess the ability of the saline test to monitor the healing of cough during corticosteroid treatment. Current guidelines on chronic cough suggest defining the underlying medical condition and specific treatment directed at it [1,2,3]. Presence of sputum eosinophilia and elevated exhaled nitric oxide (NO) levels have been shown to predict the response to a two-week treatment with ICS in patients with chronic cough [4,5]. All the above-mentioned prospective studies may be criticized for short duration and lack of a pre-determined, well validated end point to define a positive clinical response
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