What are randomized controlled studies, meta-analyses, and systematic reviews? How can I find these kinds of articles?


What are randomized controlled trails (RCT), meta-analyses, and systematic reviews? 

Randomized controlled trials (RCT) are prospective studies that measure the effectiveness of a new intervention or treatment. Although no study is likely on its own to prove causality, randomization reduces bias and provides a rigorous tool to examine cause-effect relationships between an intervention and outcome. This is because the act of randomization balances participant characteristics (both observed and unobserved) between the groups allowing attribution of any differences in outcome to the study intervention. This is not possible with any other study design (Hariton & Locascio, 2018).

Meta-analysis is a quantitative, formal, epidemiological study design used to systematically assess previous research studies to derive conclusions about that body of research. Outcomes from a meta-analysis may include a more precise estimate of the effect of treatment or risk factor for disease, or other outcomes, than any individual study contributing to the pooled analysis (Haidich, 2010).

Systematic reviews, as the name implies, typically involve a detailed and comprehensive plan and search strategy derived a priori, with the goal of reducing bias by identifying, appraising, and synthesizing all relevant studies on a particular topic. Often, systematic reviews include a meta-analysis component which involves using statistical techniques to synthesize the data from several studies into a single quantitative estimate or summary effect size [sic](Petticrew & Roberts, 2006). In contrast to traditional hypothesis testing which can give us information about statistical significance (i.e., did the intervention group differ from the control group) but not necessarily clinical significance (i.e., was this difference clinically meaningful or large), effect sizes measure the strength of the relationship between two variables, thereby providing information about the magnitude of the intervention effect (i.e., small, medium, or large) (Uman, 2011). 

If you are having a difficulty identifying if a source qualifies as any of these, read the abstract of the paper carefully. Frequently papers will explicitly state what if they are an RCT, Meta-analysis, or Systematic Review. Furthermore, RCT's will typically describe their hypothesis, methodology, experimental group, and control group. Meta-analyses and Systematic Reviews will typically describe the intervention under investigation, and the body of studies from which they are drawing data related to the intervention under investigation. If after carefully reading the abstract. 

If after reading the abstract carefully it is unclear what kind of study a source is, consult one of FCC's librarians or your professor. 

How do I find RCTs, Meta-analyses, or Systematic Reviews in the databases?

MEDLINE, CINAHL, and Academic Search Premier are good places to search for these kinds of sources. Try using a search string such as the following examples:

acl AND "systematic review"
"rotator cuff" AND "randomized controlled trial"
"spinal injury" and "meta analysis"


  • Last Updated Sep 30, 2022
  • Views 4
  • Answered By Daniel Gallaher

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