Clinical Remission in Severe Asthma: A Comparative Analysis of Patients with and Without Biologics from the Swiss Severe Asthma Registry.

Background: Severe asthma is a complex chronic airway disease. Biologic therapies are targeted monoclonal antibody treatments used in patients with uncontrolled, severe asthma, but real-world data from long-term registries and on patients who remain biologic-naïve are limited. This study compared severe asthma patients with and without biologic therapy and identified predictors of key clinical remission components. Methods: In this cross-sectional analysis of adult patients from the Swiss Severe Asthma Registry (SSAR), we compared patients treated with a biologic for ≥6 months to biologic-naïve patients (never exposed to biologics). Baseline characteristics were summarized descriptively. Multivariable logistic regression was used to identify predictors of four remission components: good asthma control (ACT ≥ 20), absence of exacerbations, no maintenance oral corticosteroid (OCS) use, and preserved lung function (FEV1 > 80% predicted). Results: Of 394 patients, 298 (75.6%) were biologic-treated and 96 (24.4%) were biologic-naïve. Biologic-treated patients more often had allergic asthma and type-2-related comorbidities, and showed better outcomes, including fewer exacerbations (0.49 vs. 1.09/year; p < 0.001) and higher ACT scores (20.0 vs. 17.2; p < 0.001). Biologic therapy was independently associated with higher odds of asthma control (OR 3.96; p = 0.006), no exacerbations (OR 5.11; p = 0.001), no OCS use (OR 6.27; p = 0.002), and FEV1 > 80% predicted (OR 4.42; p = 0.011). Overall, 24.2% of biologic-treated patients and 6.2% of biologic-naïve patients fulfilled all four remission components. Conclusions: In this real-world registry cohort, biologic-treated patients were more likely to meet individual and composite remission criteria than biologic-naïve patients. The relatively low proportion of patients achieving all four stringent criteria highlights the need to revisit current remission definitions and to adopt individualized, multidimensional treatment goals in severe asthma.