Nonadherence to inhaled preventers impairs asthma control. Electronic monitoring devices (EMDs) can objectively measure adherence. Their use has not been reported in difficult asthma patients potentially suitable for novel therapies, i.e. biologics and bronchial thermoplasty.Consecutive patients with difficult asthma were assessed for eligibility for novel therapies. Medication adherence, defined as taking >75% of prescribed doses, was assessed by EMD and compared with standardised clinician assessment over an 8-week period.Among 69 difficult asthma patients, adherence could not be analysed in 13, due to device incompatibility or malfunction. Nonadherence was confirmed in 20 out of 45 (44.4%) patients. Clinical assessment of nonadherence was insensitive (physician 15%, nurse 28%). Serum eosinophils were higher in nonadherent patients. Including 11 patients with possible nonadherence (device refused or not returned) increased the nonadherence rate to 31 out of 56 (55%) patients. Severe asthma criteria were fulfilled by 59 out of 69 patients. 47 were eligible for novel therapies, with confirmed nonadherence in 16 out of 32 (50%) patients with EMD data; including seven patients with possible nonadherence increased the nonadherence rate to 23 out of 39 (59%).At least half the patients eligible for novel therapies were nonadherent to preventers. Nonadherence was often undetectable by clinical assessments. Preventer adherence must be confirmed objectively before employing novel severe asthma therapies.
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