Long-term changes and risk factors for persistent cough and sputum in adult patients with asthma treated by Japanese specialists: The SARAS study (1997–2023)

BACKGROUND: Advances in pharmacologic therapy have improved asthma outcomes, yet persistent symptoms can challenge a subset of patients, thereby hindering clinical remission. This study aimed to assess longitudinal trends in symptom control and identify factors associated with persistent symptoms in adult patients with asthma receiving established treatments in Japan. METHODS: We analyzed data from the SApporo Real-world Asthma Survey, a repeated cross-sectional study conducted in Japan over a 26-year period (1997-2023). The participants were adult patients with asthma receiving guideline-based care from respiratory and/or allergy specialists. Data were collected through patient questionnaires and physician records. Multivariable logistic regression analysis was performed to identify risk factors for persistent symptoms. RESULTS: The median age of the analyzed 13,243 patients increased during the study (from 52 years in 1997 to 60 years in 2023), as did the proportion of women. Although nighttime symptoms, dyspnea, and unscheduled visits for exacerbation declined, 10 %-30 % of patients reported persistent cough and 20 %-40 % had sputum despite therapeutic advances. Chronic rhinosinusitis and current smoking were significant predictors of persistent symptoms. Patients undergoing intensive therapies had a higher symptom burden, although the symptom severity and unscheduled visit rates decreased within each treatment category over time. CONCLUSIONS: Despite therapeutic advances and guideline-based specialist care, residual symptoms, especially cough and sputum, persisted in a significant proportion of Japanese adult patients with asthma. Comprehensive management strategies targeting comorbidities such as chronic rhinosinusitis and smoking are essential to achieve clinical remission and improve patient-centered outcomes.