Table 4 Explanatory and practical clinical trials: Two options for clinical trials in community settings [7, 42]
From: Bridging the gap between basic science and clinical practice: a role for community clinicians
| Â | Explanatory clinical trials: | Practical clinical trials: |
|---|---|---|
Hypothesis and design | Hypothesis and study questions are designed to improve the understanding of the mechanism by which an intervention works | Hypothesis and study questions are designed to facilitate decision making |
Research question | How effective is a treatment under ideal, experimental conditions? | How effective is a treatment in every-day practice? What are the risks, benefits, and costs in every-day practice? |
Defining the patient sample | Rigorous inclusion/exclusion criteria to create a well-defined, homogenous sample of patients | Wide inclusion/exclusion criteria to reflect actual, often diverse, patient populations in clinical practices |
Practice setting | Homogeneous | Many and diverse |
Intervention | Well-specified, precise protocol with limited variation allowed; often involves treatment vs. placebo | Well-specified, precise protocol allowing variation in implementation from site to site to capture actual patient and care characteristics; often compares existing, clinically-relevant, feasible treatment alternatives (often head-to-head) |
Adequate sample size | Enough to assemble a homogenous group that will enable a study of a relationship between a single intervention and a dominant outcome measure | Often requires large sample size to account for heterogeneity in sample and long-term nature of studies |
Outcome | Well-defined; often a specific biological effect of an intervention | Often defined broadly in relation to patient's function or quality of life so effect sizes on personal and population health can be calculated |