Ethics approval and participants
respiratory or pulmonary condition, neurological abnormality, cough, asthma, word of mouth
PATHOLOGY, ASTHMA
This randomized, parallel-group, sham-controlled trial was approved by the Food and Drug Administration (Investigational New Drug (IND) #142,148) on March 1, 2021, and the University of Montana Institutional Review Board (#188 − 18) on March 25, 2021. All methods were carried out at the University of Montana in accordance with relevant guidelines and regulations. Power analysis based on projected rate of improvement (estimated from initial pilot trial results) for each group was completed to estimate sample size. A sample size of 30 was estimated for 80% power.Participants were recruited from speech-language pathology clinics in western Montana, a regional social media campaign, and word of mouth. Inclusion criteria included adults with a cough of at least eight weeks duration that had been treated unsuccessfully by at least one physician, normal chest x-ray and spirometry (unless diagnosed with asthma, further detail below), and no evidence of anatomical or neurological abnormality on laryngoscopy. Exclusion criteria included current smokers, individuals who were pregnant or trying to become pregnant, diagnosis of a respiratory or pulmonary condition other than asthma, positive case of COVID-19 within 14 days of enrollment or any active symptoms of COVID-19 (based on CDC guidelines), and those not currently or recently on an ACE-inhibitor or neuromodulator prescribed for cough. Individuals with asthma were allowed to enroll in the study if they were regularly followed by a pulmonologist who provided written documentation that the individual’s asthma was well controlled, and the participant had an FEV1% predicted of at least 0.60 prior to the beginning of each session. All participants signed an IRB-approved informed-consent form which included an agreement to avoid new cough treatments during the study. None of the participants in this trial were enrolled in the pilot 1 trial.