Research
Print page Print page
Switch language
Rigshospitalet - a part of Copenhagen University Hospital
Published

Randomized clinical trials with run-in periods: frequency, characteristics and reporting

Research output: Contribution to journalJournal articleResearchpeer-review

DOI

  1. Identification of Patients with New-Onset Heart Failure and Reduced Ejection Fraction in Danish Administrative Registers

    Research output: Contribution to journalJournal articleResearchpeer-review

  2. Central nervous system tumor registration in the Swedish Cancer Register and Inpatient Register between 1990 and 2014

    Research output: Contribution to journalJournal articleResearchpeer-review

  1. Hand cleaning with ash for reducing the spread of viral and bacterial infections: a rapid review

    Research output: Contribution to journalReviewResearchpeer-review

  2. Systematic review finds that appraisal tools for medical research studies address conflicts of interest superficially

    Research output: Contribution to journalReviewResearchpeer-review

  3. Impact of blinding on estimated treatment effects in randomised clinical trials: meta-epidemiological study

    Research output: Contribution to journalJournal articleResearchpeer-review

  4. European Society Paediatric Gastroenterology, Hepatology and Nutrition Guidelines for Diagnosing Coeliac Disease 2020

    Research output: Contribution to journalJournal articleResearchpeer-review

  5. Sertraline in primary care: comments on the PANDA trial

    Research output: Contribution to journalComment/debateResearch

View graph of relations

Background: Run-in periods are occasionally used in randomized clinical trials to exclude patients after inclusion, but before randomization. In theory, run-in periods increase the probability of detecting a potential treatment effect, at the cost of possibly affecting external and internal validity. Adequate reporting of exclusions during the run-in period is a prerequisite for judging the risk of compromised validity. Our study aims were to assess the proportion of randomized clinical trials with run-in periods, to characterize such trials and the types of run-in periods and to assess their reporting.

Materials and methods: This was an observational study of 470 PubMed-indexed randomized controlled trial publications from 2014. We compared trials with and without run-in periods, described the types of run-in periods and evaluated the completeness of their reporting by noting whether publications stated the number of excluded patients, reasons for exclusion and baseline characteristics of the excluded patients.

Results: Twenty-five trials reported a run-in period (5%). These were larger than other trials (median number of randomized patients 217 vs 90, P=0.01) and more commonly industry trials (11% vs 3%, P<0.01). The run-in procedures varied in design and purpose. In 23 out of 25 trials (88%), the run-in period was incompletely reported, mostly due to missing baseline characteristics.

Conclusion: Approximately 1 in 20 trials used run-in periods, though much more frequently in industry trials. Reporting of the run-in period was often incomplete, precluding a meaningful assessment of the impact of the run-in period on the validity of trial results. We suggest that current trials with run-in periods are interpreted with caution and that updates of reporting guidelines for randomized trials address the issue.

Original languageEnglish
JournalClinical Epidemiology
Volume11
Pages (from-to)169-184
Number of pages16
ISSN1179-1349
DOIs
Publication statusPublished - 2019

ID: 58919282