Clinical Characteristics of Cough Frequency Patterns in Patients with and without Asthma.

BACKGROUND

Cough is a frequent symptom of asthma. Cough frequency (CoFr) monitoring devices are now available to objectively measure cough counts and offer a novel endpoint to assess asthma. However, little is known about CoFr in asthma.

OBJECTIVE

The aims were, first, to determine whether unique features of CoFr exist in asthmatic and nonasthmatic patients and, secondly, to evaluate relationships between CoFr and pathophysiological parameters of asthma.

METHODS

In the current study, 73 asthmatic and 63 nonasthmatic patients suffering from persistent cough were enrolled. At study entry, the Leicester Cough Questionnaire (LCQ health status), cough visual analog scale (VAS), Leicester Cough Monitor (LCM), fractional exhaled nitric oxide (FeNO) measurements, and spirometry were performed. In asthmatic patients, the bronchial hyperresponsiveness (BHR) test was conducted if applicable. In 28 asthmatic and 17 nonasthmatic patients, LCQ, VAS, and LCM were examined before and after treatment.

RESULTS

CoFr during nighttime (asleep) was significantly higher in asthmatic patients than in nonasthmatic patients. Twenty-four-hour CoFr significantly decreased after appropriate treatment and was correlated with changes in VAS and LCQ in all patients. The improvement in cough in asthmatic patients was greater during nighttime than during daytime (awake). CoFr in asthmatic patients was significantly correlated with BHR, but not with FeNO.

CONCLUSIONS

In asthmatic patients, nocturnal CoFr can be associated with BHR, was significantly higher before treatment, but improved more after treatment compared with nonasthmatic patients. Monitoring nocturnal CoFr may provide unique and valuable information on making an early prediction of therapeutic effects in asthma.