Randomized Controlled Trial

From Health Facts
Jump to: navigation, search
Latest Edit: Iva 2012-08-04 (EDT)

Randomized controlled trials (RCTs) are considered the 'gold standard' of conventional scientific research. The intention of RCTs is to prove statistically the efficacy of a given intervention under investigation. RCTs are based on mechanist and reductionist concepts; of all study designs, the RCT is best suited to establish a linear causal relationship between a given treatment and effect. Patients in an RCT are randomly allocated to either the treatment or control group. Often this control group receives a “dummy” or inactive placebo pill in order to control for the potential psychological effects that may impact the efficacy of treatment. In this manner, RCTs attempt to isolate the effect of a single variable or treatment in order to prove the efficacy of the treatment.

There are several subtypes and ways of classifying RCTs. One of these is the pragmatic trial, which is of interest because of its use in conducting whole systems research. Pragmatic trials are "designed to find out about how effective a treatment (or group of treatments) actually is in routine, everyday practice.[1]. Explanatory RCTs typically follow the design decribed above: conducted under ideal conditions, isolating the effect of a single treatment, and comparing the efficacy of this treatment to a placebo. In a pragmatic trial, the whole combined effect of a "body" of treatments may be investigated and compared to the effect of other treatments. This type of study better mimics health care as it happens in the real world, and can help show the effectiveness of an entire system of practice, rather than of a single intervention. Several such studies conducted by the Research Department of the Canadian College of Naturopathic Medicine have shown the effectiveness of naturopathic medicine for prevention of cardiovascular disease.[2], shoulder and pain[3], [4], [5] and anxiety.[6]


  • Human level study
  • Highly controlled to limit bias
  • May establish a linear causal relationship between interventions and outcomes
  • Pragmatic trials may assess the real world effectiveness of a complex, holistic system of health care


  • The quality of findings depends on the quality of the design, including dose, outcome measures used
  • Often conducted in a highly specific population with limited generalizability to patients outside this group
  • Generally quite costly to conduct
  • Limited ability to investigate harmful effects of a treatment, due to ethical considerations towards participants
  • Difficult to study effects on events in the distant future
  • The existence of incongruent findings between industry-funded and non-industry funded trials in some areas suggests a novel source of bias
  • Not suited to testing situations or conditions involving a number of different factors or where mutual causality is a factor

For more information, see: wikipedia reference


  1. MacPhearson H (2004) Pragmatic clinical trials. Complementary Therapies in Medicine;12: 136—140.
  2. Seely D, Szczurko O, Cooley K, Fritz H, Aberdour S, Herrington C, Herman P, Rouchotas P, Lescheid D, Bradley R, Gignac T, Bernhardt B, Zhou Q, Guyatt G (2011) Naturopathic Medicine for the Prevention of Cardiovascular Disease: A Pragmatic Randomized Controlled Trial. 'CCNM.
  3. Herman PM, Szczurko O, Cooley K, Mills EJ (Mar-Apr 2008) Cost-effectiveness of naturopathic care for chronic low back pain. Altern Ther Health Med;14(2):32-9. PubMed PMID: 18383988.
  4. Szczurko O, Cooley K, Busse JW, Seely D, Bernhardt B, Guyatt GH, Zhou Q, Mills EJ (Sep 2007) Naturopathic care for chronic low back pain: a randomized trial. PLoS One;2(9):e919. PubMed PMID: 17878954.
  5. Szczurko O, Cooley K, Mills EJ, Zhou Q, Perri D, Seely D (Aug 2009) Naturopathic treatment of rotator cuff tendinitis among Canadian postal workers: a randomized controlled trial. Arthritis Rheum;61(8):1037-45. PubMed PMID: 19644905.
  6. Cooley K, Szczurko O, Perri D, Mills EJ, Bernhardt B, Zhou Q, Seely D (Aug 2009)Naturopathic care for anxiety: a randomized controlled trial. ISRCTN78958974. PLoS One;31;4(8):e6628. PubMed PMID: 19718255.