Review Question - QID 214451

Patients in factorial randomized control trials (RCT) are assigned to groups that receive a specific combination of interventions and non-interventions.

In factorial RCTs, patients are randomized to groups receiving treatment A and B, treatment A or control, treatment B or control, or no treatment. This study design is useful because two interventions can be assessed with the same study population and any interaction between the treatments can be determined (for example, does treatment A work differentially when combined with treatment B). Other randomized control trial designs include parallel, cluster, and crossover. Parallel studies are performed by having two or more groups that exclusively have one intervention without group overlap. Crossover studies have each group receive each intervention in a random sequence. Cluster design studies have pre-existing groups of participants (such as schools, or cities) that are randomly selected to receive or not receive an intervention.

Karlsson and the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine published an exhaustive guide to research for evidence-based medicine in a step-wise fashion. They cover levels of evidence, design for randomized control trials and the CONSORT checklist. They also describe proper study design of cohort, case-control, case series, systematic review, meta-analysis studies. The second half of the guide discusses appropriate outcome measures, statistical analyses, and data interpretation, reporting complications, and concludes with steps to writing a scientific article.

Incorrect Answers:
Answer 1: Parallel RCTs are when each study group receives or does not receive an intervention.
Answer 2: Cluster RCTs are when pre-existing groups are assigned to receive or not receive an intervention.
Answer 3: This is not an RCT. Cohort studies are longitudinal studies looking at a known exposure for a possible later outcome (such as a disease).
Answer 5: Crossover RCTs are when each study group receives or does not receive an intervention in a random sequence.