Attitudes and practices regarding dosing interval extension of biologics in severe asthma: a nationwide survey and real-world data from the Dutch RAPSODI registry

Background: Biologics in severe asthma are an effective but costly treatment. A personalized dosing strategy could reduce treatment burden and improve cost-effectiveness. Objective: To explore physician attitudes and real-world practices regarding dosing interval extensions for biologics in severe asthma. Methods: We assessed attitudes to dosing interval extension among Dutch pulmonologists prescribing biologics through a 28-item nationwide e-survey and investigated clinical practices using data from the Dutch severe asthma registry RAPSODI (Dutch Registry of Adult Patients with Severe asthma for Optimal DIsease management). Results: Of 50 pulmonologists, 39 (78%) reported extending dosing intervals, primarily due to good clinical response (95%) and treatment costs (77%). Most required at least 1 year of stable asthma (82%), which respondents defined as 6-item Asthma Control Questionnaire score less than 1.5, stable lung function, absence of exacerbations, and no maintenance oral corticosteroids. Reported success rates exceeded 50% for 62% of respondents, with failures mainly due to exacerbations or worsening symptoms. Interval extension was more frequent among physicians treating more than 25 patients with severe asthma (P < .01). Major barriers included lack of evidence (63%) and experience (52%), yet 91% expressed a wish to extend intervals more often. In RAPSODI (n = 1603), 159 interval extensions were recorded in 138 patients across 14 hospitals. Median increase in interval relative to the standard interval was 50% (range, 12.5%-300%) with multiple sequential extensions in 14% of patients. In 2024, the annual incidence of extensions was 5.2%, and the prevalence was 11.4%. Conclusions: A vast majority of Dutch pulmonologists already apply dosing interval extension of biologics in severe asthma, however on a limited scale. Although the frequency is increasing, clinicians are reluctant to apply extension broadly due to limited experience and evidence, highlighting the need for evidence-based guidelines.