Study design
Each participant visited the clinic once and was tested with
a single-breath capsaicin provocation. The cough thresholds
of the study participants were registered manually during
the provocations. Cough was defined as the characteristic
sound that follows a forced expiratory effort against a
closed glottis and distinguished from other sounds such as
clearing the throat [13,26], by a discretionary decision of
the investigator upon observation of the subjects. The total
time for each provocation was about 15 min.