Objectives: The primary aim of this study was to assess the efficacy of internet-based behavioral cough suppression therapy (IBCST). The secondary aim was to understand the experience of IBCST users through semi-structured interviews.

Design: The study included a prospective, single-blind, randomized, controlled trial comparing the efficacy of a five-week IBCST and control intervention consisting of healthy lifestyle education in patients with refractory chronic cough. Semi-structured qualitative interviews were also conducted and analyzed using grounded theory methodology.

Participants: Thirty-nine adult participants with refractory chronic cough were enrolled. Of these, 30 completed the intervention.

Interventions: Both IBCST and the healthy lifestyle education control included five weeks of asynchronous content delivered via video and text on a study-specific website. The participants accessed new content and home exercise recommendations each week. The IBCST intervention included education on cough hypersensitivity syndrome and the rationale for BCST, vocal hygiene education, instruction in cough suppression strategies, functional practice of cough suppression in daily life, and implications for long-term management. The healthy lifestyle education intervention was based on publicly available information from the Centers for Disease Control and Prevention, and included general education, physical activity, healthy eating, stress management, and relaxation techniques. Ambulatory cough frequency monitoring with a smartwatch was completed in a subgroup of participants.

Outcomes: The Leicester Cough Questionnaire (LCQ) and Cough Severity Visual Analog Scale (VAS) were the primary and secondary outcome measures, respectively, and were administered at baseline, one-week post-treatment, and one-month post-treatment. Semi-structured qualitative interviews were conducted with a subgroup of IBCST participants.

Results: Thirty participants (27 women; mean age, 61 years) with refractory chronic cough were included (18 IBCST, 12 control). IBCST resulted in clinically significant improvements in LCQ total score at one-week post-treatment (mean = 3.74) compared to the control group (mean difference between groups = 3.24, 95% CI = 0.72-5.76, standard error = 1.227, p=0.014), and one-month post-treatment (mean = 4.1) compared to the control group (mean difference between groups = , 95% CI = 0.286 to 6.32, p = 0.033). VAS changes did not reach the minimum clinically meaningful threshold but trended in that direction for the IBCST group at one-week post-treatment (mean difference between groups = -16.1, 95% CI = -32.7-0.46, p = 0.056). Qualitative analysis revealed that IBCST participants liked the convenience and quality of treatment and experienced improvements in symptom control. Ambulatory cough frequency monitoring for the target period of six weeks was difficult for most participants to achieve.

Conclusions: IBCST was feasible, efficacious, and resulted in total LCQ score changes on par with what has been reported for other BCST interventions (approximately 4-point change). This work paves the way for future adaptations of other specialized voice and upper airway treatments to asynchronous, online modalities and supports the future adaptation of BCST into a digital therapeutic.