Obesity Surgery

, Volume 28, Issue 3, pp 862–863 | Cite as

Randomized Controlled Trials or Observational Studies? It Depends on the Research Question

  • John B. Dixon
Brief Communication

The fundamentals of clinical research require that a study is designed to answer an important research question. Randomized controlled trials (RCTs) play a core role in assessing the safety and efficacy of health care interventions or for comparing interventions. RCTs are designed to reduce bias and variability and therefore examine the true effect of an intervention. Reducing bias increases the reliability, and reducing variability improves the precision of the outcome. Groups must be alike and only vary in the intervention they receive. RCTs and even meta-analyses of RCT results can be quite inappropriate when trying to answer other research questions.

Predicting who will respond best to a bariatric-metabolic surgical procedure requires a different approach. For this, we want variability and great detail about each individual prior to the surgical treatment, as now, we want to understand factors influencing the individual’s response. Baseline duration of type 2 diabetes, utilization...


Research design Randomized trials Observational studies Bariatric-metabolic surgery 


Compliance with Ethical Standards

Conflict of Interest

Dr. Dixon reports grants from NHMRC, during the conduct of the study, personal fees from Bariatric Advantage, personal fees from Nestle Health Science, personal fees from I-Nova, personal fees from Medtronic, personal fees from Apollo Endosurgery, and personal fees from Novo Nordisk, outside the submitted work;

Ethical Statement

This article does not contain any studies with human participants or animals performed by any of the authors.

Informed Consent

An informed consent statement does not apply to this manuscript.


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    Rubino F, Nathan DM, Eckel RH, et al. Metabolic surgery in the treatment algorithm for type 2 diabetes: a joint statement by international diabetes organizations. Diabetes Care. 2016;39(6):861–77. Scholar
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    Wu GZ, Cai B, Yu F, et al. Meta-analysis of bariatric surgery versus non-surgical treatment for type 2 diabetes mellitus. Oncotarget. 2016;7(52):87511–22.PubMedPubMedCentralGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2017

Authors and Affiliations

  1. 1.Baker Heart and Diabetes InstituteMelbourneAustralia
  2. 2.Iverson Health Innovation Research InstituteSwinburne UniversityMelbourneAustralia
  3. 3.Primary Care Research UnitMonash UniversityMelbourneAustralia

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