(in)Appropriate LAMA Prescribing in Asthma patients: a Cohort Analysis (the ALPACA study)

Abstract

Introduction: Although long-acting muscarinic antagonists (LAMA) are only indicated as add-on therapy in asthmatic patients, there are concerns of monotherapy use. Aim: To study the prevalence of LAMA monotherapy and its potential association with severe asthma exacerbations (SAE) in patients with asthma. Methods: A cohort study (2007-2017) in the IPCI primary care database, in asthma patients aged 6-50, using LAMA during follow-up. Respiratory prescriptions were retrieved from the electronic medical records based on ATC code. Asthma treatment periods were categorized as LAMA mono, double (LAMA+ICS), or triple therapy (LAMA+ICS+LABA). Patients characteristics (age, sex, history of exacerbations, and comorbidities) were collected at the start of each treatment period. A Poisson regression analysis was performed to calculate the relative rate (RR) of SAE, adjusting for patient characteristics. Results: From a total of 66,508 asthma patients, 1,238 (1.9%) LAMA users were identified, with a median age of 41 years and 65.9% females. From a total of 3,596 LAMA treatment periods, 1,390 (38.7%) were considered LAMA mono therapy, 553 (15.4%) double therapy and 1,653 (46.0%) triple therapy. In all patients using LAMA, the RR of SAE during monotherapy compared to double therapy was 1.6 (p=0.42). When excluding patients who ever used triple therapy the RR increased to 5.7 (p=0.02). Conclusions: This observational study shows that LAMA is frequently prescribed as monotherapy (i.e. without concurrent ICS) which is associated with an increased risk of exacerbations. This emphasizes the need to check for ICS use when prescribing LAMA to asthmatic patients.