run-in period

Run-in period is a period between the recruitment and randomization phases of a clinical trial,{{cite journal | last1=Laursen | first1=David Ruben Teindl | last2=Paludan-Müller | first2=Asger Sand | last3=Hróbjartsson | first3=Asbjørn | title=Randomized clinical trials with run-in periods: frequency, characteristics and reporting | journal=Clinical Epidemiology | publisher=Informa UK Limited | volume=11 | year=2019 | issn=1179-1349 | pmid=30809104 | pmc=6377048 | doi=10.2147/clep.s188752 | pages=169–184 | doi-access=free }}{{cite web |url=http://www.medilexicon.com/medicaldictionary.php?t=67147 |archive-url=https://web.archive.org/web/20160304031735/http://www.medilexicon.com/medicaldictionary.php?t=67147 |archive-date=2016-03-04 |title=run-in period |work=Stedman's Medical Dictionary |year=2006 |publisher=Lippincott Williams & Wilkins |via=MediLexicon}} when all participants receive the same treatment, which may be active treatment, a placebo or no treatment at all. The clinical data from this stage of a trial are only occasionally of value but can serve a valuable role in screening out ineligible or non-compliant participants, in ensuring that participants are in a stable condition, and in providing baseline observations.{{cite web |url=http://www.nephjc.com/news/run-in-period |date=September 13, 2021 |title=Run-in periods in clinical trials: What can we ACHIEVE? |work=NephJC |first=Manasi |last=Bapat}} A run-in period is sometimes called a washout period if treatments that participants were using before entering the clinical trial are discontinued.{{cn|date=November 2023}}