title: Systematic review of stepped wedge cluster randomized trials shows that design is particularly used to evaluate interventions during routine implementation.
abstract: OBJECTIVE
  To describe the application of the stepped wedge cluster randomized controlled trial (CRCT) design.
  
  
  METHODS
  Systematic review. We searched Medline, Embase, PsycINFO, HMIC, CINAHL, Cochrane Library, Web of Knowledge, and Current Controlled Trials Register for articles published up to January 2010. Stepped wedge CRCTs from all fields of research were included. Two authors independently reviewed and extracted data from the studies.
  
  
  RESULTS
  Twenty-five studies were included in the review. Motivations for using the design included ethical, logistical, financial, social, and political acceptability and methodological reasons. Most studies were evaluating an intervention during routine implementation. For most of the included studies, there was also a belief or empirical evidence suggesting that the intervention would do more good than harm. There was variation in data analysis methods and insufficient quality of reporting.
  
  
  CONCLUSIONS
  The stepped wedge CRCT design has been mainly used for evaluating interventions during routine implementation, particularly for interventions that have been shown to be effective in more controlled research settings, or where there is lack of evidence of effectiveness but there is a strong belief that they will do more good than harm. There is need for consistent data analysis and reporting.
authors.affiliation: York Trials Unit, Department of Health Sciences, University of York, Heslington, York YO10 5DD, UK. nm619@york.ac.uk
authors.forename: Noreen D
authors.initials: ND
authors.lastname: Mdege
authors.forename: Mei-See
authors.initials: MS
authors.lastname: Man
authors.forename: Celia A
authors.initials: CA
authors.lastname: Taylor Nee Brown
authors.forename: David J
authors.initials: DJ
authors.lastname: Torgerson
mesh_terms: D016000:Cluster Analysis; D057186:Comparative Effectiveness Research; D018592:Cross-Over Studies; D003627:Data Interpretation, Statistical; D016206:Databases, Bibliographic; D006801:Humans; D016032:Randomized Controlled Trials as Topic / Q000941:ethics / Q000379:methods* / Q000706:statistics & numerical data; D012107:Research Design; D057212:Therapeutic Equipoise; D013997:Time Factors