Adherence: meaningful outcome measure or explanatory variable?

Title: Adherence – meaningful outcome measure or explanatory variable?

Lead Investigator: Gene Colice, Pulmonary, Critical Care and Respiratory Services, Washington Hospital Center, and The George Washington University School of Medicine.
Research Team:

  • Cynthia Rand, USA
  • David Price, UK
  • Hilary Pinnock, UK
  • Iain Small, UK
  • Janet Holbrook, USA
  • Randall Brown, USA
  • Miguel Román Rodríguez, Spain
  • Alex Dima, The Netherlands
  • Michelle Eakin, USA
  • Eric van Ganse, France
  • Nemr Eid, USA


  • Good medication adherence is typically encouraged to improve treatment outcomes. Thus, good adherence can commonly be assumed to be associated with good treatment-related outcomes.
  • In clinical practice, adherence to ICS in excess of the label-defined dosing interval appears to be a marker of poorer asthma control. 
  • A medication possession ratio in excess of 100% (i.e. prescribing in excess of the label-defined dosing period) may be a simple tool to identify patients in need of more intensive evaluation – exploratory data (submitted to the 2013 ERS for consideration) show severe exacerbations are more common and asthma control attainment lower in patients with MPR >100% than in patients with MPR≤100%

Work is required to further investigate the true relationships between medication adherence, disease severity and treatment outcomes so that “drug consumption” can be meaningfully interpreted as either a treatment-related outcome, or as an explanatory variable.

Dataset: This study is its early planning phase and the dataset for use has yet to be decided. Options include:

  • The ELEVATE dataset: ELEVATE were two parallel, multicenter, pragmatic trials to evaluate the real-world effectiveness of a leukotriene-receptor antagonist (LTRA) as compared with either an  inhaled glucocorticoid for first-line asthma-controller therapy or a long-acting beta(2)-agonist (LABA) as add-on therapy in patients already receiving inhaled glucocorticoid therapy. The resultant dataset includes: demographic data (age, sex), comorbid chronic respiratory conditions, comorbid rhinitis and adherence to medication (evaluated vs questionnaire reported [RQLQ]), reversibility, smoking status, ACQ, MiniAQLQ, Royal College of Physicians’ 3 / 21 questions and patient-defined targets and symptom diary card, etc. 
  • The CYMPLA dataset: Mobile phone-based structured intervention to achieve asthma control in patients with uncontrolled persistent asthma: a pragmatic randomised controlled trial.
  • Optimum Patient Care Research Database (OPCRD)The OPCRD is a UK respiratory dataset containing anonymized, longitudinal, research-quality clinical records and patient-reported outcome data from practices that subscribe to OPC for respiratory review services; the database includes in excess of 341,000 patients at 176 practices. It has Multicentre Research Ethics Committee (MREC) approval for medical research.

Sponsor: The study analysis is funded by the Respiratory Effectiveness Group. Co-funding may be provided by Research in Real Life Ltd (depending on the dataset selected to optimise the analysis)


  • Study protocol approved and finalised by the Working group.
  • Annonymised Data Ethics and Protocol Transparency (ADEPT) Committee approval secured for use of the OPCRD for the proposed study (ADEPT approval number 2.9)
  • Study registered with the European Network of Centres for Pharmacoepidemiology and Pharmacovigilance Research (ENCePP) – click here to access the ENCePP study record
  • Study to commence February 2014.

Links (these links will become activated as the various study outputs become available):

  • Abstracts (an abstract has been submitted to the European Respiratory Society for their September 2013 Conference)
  • Posters
  • Presentations
  • Final publications

Related reading:

Contact us at if you are interested in collaborating on this study, or would like to find out further information about the protocol.

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