Prospective Study to Evaluate the Effectiveness of Guideline-Based Therapy for Chronic Cough and Refractory Chronic Cough (PROCOUGH)

Rationale Chronic cough is a common and burdensome condition with limited licensed therapies. Current guidelines recommend identifying treatable traits and using off-label therapies based largely on small clinical trials, but the real-world effectiveness of this approach remains unclear. Objective To evaluate the effectiveness of guideline-based therapies on objective and patient-reported outcomes in patients with chronic cough attending a tertiary cough clinic. Methods PROCOUGH was a prospective, single-centre, observational cohort study conducted at McMaster University Medical Centre (December 2021–May 2025). Adults with chronic cough (>8 weeks) underwent comprehensive assessment, including lung function testing, airway inflammation measures, sputum cytology, and 24-hour cough monitoring (VitaloJAK™), alongside patient-reported outcomes. Patients were treated according to ERS guideline recommendations, with all assessments repeated after a treatment trial. The primary outcome was change in 24-hour cough frequency. Secondary outcomes included Leicester Cough Questionnaire (LCQ) and Cough Severity VAS (CS-VAS). Responder analyses were based on ≥30% cough frequency reduction, ≥30 mm CS-VAS improvement, and ≥1.3-point LCQ increase. Results One hundred patients completed follow-up (mean age 58.1±14.0 years; 58% female; median cough duration 7 years). Treatment resulted in a 54% reduction in 24-hour cough frequency (95% CI 42.0–62.9%), a 20.2-mm decrease in CS-VAS (95% CI −26.2 to −14.2), and a 3.4-point increase in LCQ (95% CI 2.6–4.2). Individually, 56%, 36%, and 64% met cough frequency, CS-VAS, and LCQ responder criteria, respectively, but only 14% met all three. Despite treatment, 71% reported insufficient cough control. Conclusion Guideline-based therapy improves objective and subjective cough outcomes; however, most patients fail to achieve satisfactory symptom control, highlighting a substantial unmet need for effective treatments for refractory unexplained chronic cough.