Outcomes and Benefits of Using Twice Daily Nebulised Hypertonic Saline in T2-Low and T2-High Asthma With Bronchial Hypersecretion: A Retrospective Cohort Study

Objective Patients with T2-low and T2-high asthma have limited treatment options. Our study aims to evaluate the efficacy of nebulised hypertonic saline (HS) as an adjunctive treatment in this cohort. Specifically, the study aims to evaluate whether HS is tolerated in these patients, given the historical concerns with HS-induced bronchoconstriction. Additionally, it aims to determine whether nebulised HS reduces the frequency of exacerbations and hospital admissions in patients with T2-low and T2-high asthma. Methods This retrospective cohort study reviewed adults with T2-low and T2-high asthma with a bronchial hypersecretion phenotype who underwent a successful trial of nebulised HS across two district general hospitals within Betsi Cadwaladr University Health Board in the United Kingdom between February 2023 and August 2025. We included patients who successfully tolerated the initial HS trial and remained on treatment for at least 12 months. Of the 48 people who passed the initial HS tolerance test, only 44 went on to continue the treatment for over a year. The clinical data, including asthma exacerbations requiring primary care treatment or hospital admissions, were compared between 12 months prior to starting treatment and 12 months after HS initiation. Pre- and post-treatment exacerbation frequencies and hospital admissions were compared using the paired Wilcoxon signed-rank test, with a statistical significance of p < 0.05. Results Of the 48 patients who passed the trial of nebulised HS, 44 remained on treatment after one year. The mean number of asthma exacerbations decreased significantly from 2.18 in the year before HS initiation to 1.20 in the year after treatment (p < 0.001). Mean hospital admissions due to acute asthma exacerbations significantly decreased, from 0.43 to 0.15 (p-value 0.006). Eleven patients (25%) were commenced on biologic therapy during the year following HS initiation. Conclusion Patients with T2-low and T2-high asthma who were started on long-term nebulised HS tolerated treatment well, and most remained on therapy at one year. Comparing the 12 months before and after starting HS, we found a statistically significant reduction in both exacerbations and hospital admissions. These findings suggest a potential role for nebulised HS as an adjunctive treatment in this patient group. However, this was an observational study, so we cannot establish causality, and confounding factors such as initiation of biologic therapy may have an influence. The findings are also limited as patients included are only from two hospitals, which results in reduced confidence in the generalisability of the findings to the wider population with the same diagnosis. Large-scale, prospective, controlled studies are required to confirm the efficacy of nebulised HS in this population.