title: Systematic review of adherence rates by medication class in type 2 diabetes: a study protocol.
abstract: BACKGROUND
  Treatment options for type 2 diabetes are becoming increasingly complex with people often prescribed multiple medications, and may include both oral and injectable therapies. There is ongoing debate about which drug classes provide the optimum second-line and third-line treatment options. In the real world, patient adherence and persistence determines medication effectiveness. A better understanding of adherence may help inform the choice of second-line and third-line drug classes.
  
  
  METHODS
  This systematic review will compare adherence and persistence rates across the different classes of medication available to people with type 2 diabetes. It will include all identified studies comparing medication adherence or persistence between two or more glucose-lowering medications in people with type 2 diabetes. Research databases (MEDLINE, EMBASE, The Cochrane Library, The Register of Controlled Trials, PsychINFO and CINAHL) will be searched for relevant articles, using a comprehensive search strategy. All identified medication trials and observational studies will be included which compare adherence or persistence across classes of diabetes medication. The characteristics and outcomes of all the included studies will be reported along with a study quality grade, assessed using the Cochrane Risk Assessment Tool. The quality of adjustment for confounders of adherence or persistence will be reported for each study. Where multiple (n ≥ 3) studies provide compare adherence or persistence across the same 2 medication classes, a meta-analysis will be performed.
  
  
  BACKGROUND
  No ethics approval is required. This review and meta-analysis (where possible) will provide important information on the relative patient adherence and persistence, with the different classes of diabetes therapies. Once complete, the results will be made available by peer-reviewed publication.
  
  
  BACKGROUND
  CRD42015027865.
authors.affiliation: Section of Clinical Medicine and Aging, University of Surrey, Guildford, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: McGovern
authors.affiliation: Section of Clinical Medicine and Aging, University of Surrey, Guildford, UK.
authors.forename: Zayd
authors.initials: Z
authors.lastname: Tippu
authors.affiliation: Section of Clinical Medicine and Aging, University of Surrey, Guildford, UK.
authors.forename: William
authors.initials: W
authors.lastname: Hinton
authors.affiliation: Section of Clinical Medicine and Aging, University of Surrey, Guildford, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Munro
authors.affiliation: Section of Clinical Medicine and Aging, University of Surrey, Guildford, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Whyte
authors.affiliation: Section of Clinical Medicine and Aging, University of Surrey, Guildford, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: de Lusignan
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D012107:Research Design; D000078202:Systematic Reviews as Topic; D016903:Drug Monitoring
chemical_list: D007004:Hypoglycemic Agents
keywords: Hypoglycemic Agents; Insulin; Medication Adherence; Patient Compliance; Review; Type 2 Diabetes Mellitus