Selecting and describing control conditions in mobile health randomized controlled trials : A proposed typology

Hundreds of randomized controlled trials (RCTs) have tested the efficacy of mobile health(mHealth) tools for a wide range of mental and behavioral health outcomes. These RCTs haveused a variety of control condition types which dramatically influence the scientific inferencesthat can be drawn from a given study. Unfortunately, nomenclature across mHealth RCTs isinconsistent and meta-analyses commonly combine control conditions that differ in potentiallyimportant ways. We propose a typology of control condition types in mHealth RCTs. We define11 control condition types, discuss key dimensions on which they differ, provide a decision treefor selecting and identifying types, and describe the scientific inferences each comparisonallows. We propose a five-tier evidence quality gradation along with four simplifiedcategorization schemes. Lastly, we discuss unresolved definitional, ethical, and meta-analyticissues related to categorization of control conditions in mHealth RCTs.