title: Waiting list randomized controlled trial within a case-finding design: methodological considerations.
abstract: OBJECTIVE
  Randomized controlled trials (RCTs) are widely used in health care research to provide high-quality evidence of effectiveness of an intervention. However, sometimes a study does not require an RCT in order to answer its primary objective; a case-finding design may be more appropriate. The aim of this paper was to introduce a new study design that nests a waiting list RCT within a case-finding study.
  
  
  METHODS
  An example of the new study design is the DOC Study, which primarily aims to determine the diagnostic accuracy of lung function tests for chronic obstructive pulmonary disease. It also investigates the impact of lung function tests on smoking behaviour through use of a waiting list design. The first step of the study design is to obtain participants' consent. Individuals are then randomized to one of two groups; either the 'intervention now' group or the 'intervention later' group, that is, participants are placed on a waiting list. All participants receive the same intervention; the only difference between the groups is the timing of the intervention.
  
  
  CONCLUSIONS
  The design addresses patient preference issues and recruitment issues that can arise in other trial designs. Potential limitations include differential attrition between study groups and potential demoralization for the 'intervention later' group. The 'waiting list case-finding trial' design is a valuable method that could be applied to case-finding studies; the design enables the case-finding component of a study to be maintained while simultaneously exploring additional hypotheses through conducting a trial.
authors.affiliation: York Trials Unit, Department of Health Sciences, University of York, York, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Ronaldson
authors.forename: Joy
authors.initials: J
authors.lastname: Adamson
authors.forename: Lisa
authors.initials: L
authors.lastname: Dyson
authors.forename: David
authors.initials: D
authors.lastname: Torgerson
mesh_terms: D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000453:epidemiology; D012107:Research Design; D012129:Respiratory Function Tests; D012680:Sensitivity and Specificity; D012907:Smoking / Q000453:epidemiology / Q000523:psychology*; D013997:Time Factors; D014850:Waiting Lists
keywords: COPD; case finding; diagnostic accuracy; method; randomized controlled trial; waiting list