title: A Method to Calculate Adherence to Inhaled Therapy that Reflects the Changes in Clinical Features of Asthma.
abstract: Currently, studies on adherence to inhaled medications report average adherence over time. This measure does not account for variations in the interval between doses, nor for errors in inhaler use.
  
  
  
  To investigate whether adherence calculated as a single area under the (concentration-time) curve (AUC) measure, incorporating the interval between doses and inhaler technique, was more reflective of patient outcomes than were current methods of assessing adherence.
  
  
  
  We attached a digital audio device (INhaler Compliance Assessment) to a dry powder inhaler. This recorded when the inhaler was used, and analysis of the audio data indicated if the inhaler had been used correctly. These aspects of inhaler use were combined to calculate adherence over time, as an AUC measure. Over a 3-month period, a cohort of patients with asthma was studied. Adherence to a twice-daily inhaler preventer therapy using this device and clinical measures were assessed.
  
  
  
  Recordings from 239 patients with severe asthma were analyzed. Average adherence that was based on the dose counter was 84.4%, whereas the ratio of expected to observed accumulated AUC, actual adherence, was 61.8% (P < 0.01). Of all the adherence measures, only adherence calculated as AUC reflected changes in asthma quality of life, β-agonist reliever use, and peak expiratory flow over the 3 months (P < 0.05 compared with other measures of adherence).
  
  
  
  Adherence that incorporates the interval between doses and inhaler technique, and calculated as AUC, is more reflective of changes in quality of life and lung function than are the currently used measures of adherence. Clinical trial registered with www.clinicaltrials.gov (NCT 01529697).
authors.affiliation: 1 Department of Respiratory Medicine.|2 Clinical Research Centre.
authors.forename: Imran
authors.identifier: 0000-0003-1992-0280
authors.initials: I
authors.lastname: Sulaiman
authors.affiliation: 3 Special Chemistry Division, Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA.
authors.forename: Jansen
authors.initials: J
authors.lastname: Seheult
authors.affiliation: 2 Clinical Research Centre.
authors.forename: Elaine
authors.initials: E
authors.lastname: MacHale
authors.affiliation: 4 Population Health Sciences, and.
authors.forename: Fiona
authors.initials: F
authors.lastname: Boland
authors.affiliation: 5 School of Pharmacy and Pharmaceutical Sciences.
authors.forename: Susan M
authors.initials: SM
authors.lastname: O'Dwyer
authors.affiliation: 2 Clinical Research Centre.
authors.forename: Viliam
authors.initials: V
authors.lastname: Rapcan
authors.affiliation: 2 Clinical Research Centre.
authors.forename: Shona
authors.initials: S
authors.lastname: D'Arcy
authors.affiliation: 1 Department of Respiratory Medicine.
authors.forename: Breda
authors.initials: B
authors.lastname: Cushen
authors.affiliation: 1 Department of Respiratory Medicine.
authors.forename: Matshediso
authors.initials: M
authors.lastname: Mokoka
authors.affiliation: 2 Clinical Research Centre.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Killane
authors.affiliation: 5 School of Pharmacy and Pharmaceutical Sciences.
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Ryder
authors.affiliation: 6 Trinity Centre of Bioengineering.|7 School of Medicine, and.|8 School of Engineering, Trinity College, The University of Dublin, Dublin, Ireland.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Reilly
authors.affiliation: 1 Department of Respiratory Medicine.|2 Clinical Research Centre.|9 Department of Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Costello
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001249:Asthma / Q000188:drug therapy*; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007494:Ireland; D008297:Male; D008875:Middle Aged; D009330:Nebulizers and Vaporizers / Q000706:statistics & numerical data; D011446:Prospective Studies; D011788:Quality of Life; D016037:Single-Blind Method; D016896:Treatment Outcome; D016903:Drug Monitoring
chemical_list: D001993:Bronchodilator Agents
keywords: adherence; asthma; clinical outcomes; inhaler