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Comment
. 2020 May 14;20(1):239.
doi: 10.1186/s12888-020-02641-w.

Interpretation of within-group change in randomised trials

Kypros Kypri  1
Affiliations
Comment

Interpretation of within-group change in randomised trials

Kypros Kypri. BMC Psychiatry. .

Abstract

In medicine, it is common to observe improvement after intervention, at least partly because patients present for care in extremis and would have improved without intervention. Controlling for this counterfactual explanation for improvement is the principle reason to conduct a trial in which patients are randomised to treatment or a control group. Accordingly, it is not reasonable to infer that both interventions are effective when the groups show similar improvements in outcome.

Keywords: Equipoise; Inference; Randomisation; Regression to the mean; Treatment; Trial.

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Conflict of interest statement

I have no competing interests.

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References

    1. Säfsten E, Forsell Y, Ramstedt M, Damström Thakker K, Galanti MR. A pragmatic randomised trial of two counselling models at the Swedish national alcohol helpline. BMC Psychiatry. 2019;19(1):213. doi: 10.1186/s12888-019-2199-z. - DOI - PMC - PubMed
    1. GBD 2016 Alcohol Collaborators Alcohol use and burden for 195 countries and territories, 1990–2016: a systematic analysis for the global burden of disease Study 2016. Lancet. 2018;392(10152):1015–1035. doi: 10.1016/S0140-6736(18)31310-2. - DOI - PMC - PubMed
    1. Säfsten E, Forsell Y, Ramstedt M, Galanti MR. Comparing counselling models for the hazardous use of alcohol at the Swedish National Alcohol Helpline: study protocol for a randomised controlled trial. Trials. 2017;18(1):257. doi: 10.1186/s13063-017-2005-5. - DOI - PMC - PubMed
    1. Barnett AG, van der Pols JC, Dobson AJ. Regression to the mean: what it is and how to deal with it. Int J Epidemiol. 2005;34(1):215–220. doi: 10.1093/ije/dyh299. - DOI - PubMed
    1. Kypri K. Methodological issues in alcohol screening and brief intervention research. Subst Abus. 2007;28(3):31–42. doi: 10.1300/J465v28n03_04. - DOI - PubMed

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