Determinants of asthma control and quality of life in stable asthma: evaluation of two new cough provocation tests

Authors


  • Authorship and contributorship

    Minna Purokivi designed the study, recruited the subjects, and collected and analysed the data. She had the main responsibility of writing the manuscript. Heikki Koskela took part in the study planning, recruited the subjects and took part in the writing process. Kirsi Kontra took part in the study planning, was responsible for production of hypertonic saline solutions and quality control, and took part in the writing process.

  • Ethics

    The present study has been reviewed by the Research Ethics Committee, Hospital District of Northern Savo, and it has been performed in accordance with the ethical standards laid down on the 2000 Declaration of Helsinki. All patients gave their written informed consent.

  • Conflicts of interest

    The authors have stated explicitly that there are no conflicts of interest in connection with this article.

Correspondence

Minna Purokivi, MD, Center for Medicine and Clinical Research, Division of Respiratory Medicine, Kuopio University Hospital, P.O.Box 1777, 70211

Kuopio, Finland.

Tel: +358 44 717 4795

Fax: +358 17 17 2683

email: minna.purokivi@kuh.fi

Abstract

Introduction

Asthma control and quality of life are poorly associated with traditional asthma biomarkers.

Objectives

In the present study, we evaluated two new cough provocation tests in this respect.

Methods

Asthma Control Questionnaire and Leicester Cough Questionnaire were completed by 36 stable asthmatics. Cough provocation tests with hypertonic saline and isocapnic hyperpnoea of dry air were performed, as well as spirometry, ambulatory peak expiratory flow (PEF) monitoring and exhaled nitric oxide (eNO) measurement.

Results

Leicester Cough Questionnaire score correlated closely with cough responsiveness to hypertonic saline and isocapnic hyperpnoea (R = −0.66, P < 0.001 and R = −0.49, P = 0.002, respectively). Asthma Control Questionnaire score also correlated with the cough responsiveness to these tests (R = 0.52, P = 0.001 and R = 0.43, P = 0.008, respectively). Forced expiratory volume in 1 s (%predicted), diurnal PEF variation and eNO did not correlate with cough-related quality of life but showed some association with asthma control. There was a significant correlation between Leicester Cough Questionnaire and Asthma Control Questionnaire (R = −0.54, P = 0.001).

Conclusions

Asthma control and cough-related quality of life are more closely associated with cough responsiveness to the investigated cough provocation tests than to eNO and traditional indices of bronchial obstruction. Cough is a major contributor to poor asthma control.

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