Table 2.

Key Clinical Trial Terminology for this Topical Review

Explanatory Trial	Primary aim of determining how an intervention performs under ideal conditions (i.e. efficacy).
Pragmatic Trial	Primary aim of determining how an intervention performs in real world conditions (i.e. effectiveness).
Embedded Trial	Performed in clinical setting with interventions delivered by health care providers as part of routine care.
Cluster Randomized Trial	Unit of randomization is at a level other than individual (e.g., clinic or hospital).
Type 1 Hybrid Effectiveness-Implementation Trial	Primary aim is to determine intervention effectiveness and secondary aim is to gain better understanding of implementation of intervention. Example Primary Aim: Determine if mindfulness-based stress reduction improves physical function for those with chronic low back, when compared to usual medical care. Example Secondary Aim: Determine what percentage of individuals with chronic low back pain completed the entire mindfulness-based stress reduction program.
Type 2 Hybrid Effectiveness-Implementation Trial	Co-primary aims to simultaneously determine intervention effectiveness and impact of implementation strategies. Example Primary Aim: Determine if mindfulness-based stress reduction improves physical function for those with chronic low back, when compared to usual medical care. Example Primary Aim: Determine best method of mindfulness-based stress reduction program training (in-person vs. on-line vs. hybrid) for improving provider competence.
Type 3 Hybrid Effectiveness-Implementation Trial	Primary aim is to test implementation strategy and secondary aim is to describe associated clinical outcomes. Example Primary Aim: Determine best method of mindfulness-based stress reduction program training (in-person vs. on-line vs. hybrid) for improving provider competence. Example Secondary Aim: Compare clinical outcomes for patients seeking care from providers that completed in-person training vs. on-line training.