Pilot trials may improve the quality of full-scale trials: a meta-research study

Xiangji Ying, Stephan Ehrhardt

Research output: Contribution to journalArticlepeer-review


Objectives: Evidence on the value of pilot trials for subsequent trial's quality is scarce. This study aims to determine if a pilot trial improves the quality of the full-scale trial. Study Design and Setting: We searched PubMed for pilot trials and their subsequent full-scale trials. The meta-analysis of the full-scale trials was used to identify other full-scale trials on the same research topic but without a pilot trial. Markers of trial quality included publication outcomes and Cochrane Risk of Bias (RoB) assessment. Results: Fifty-eight full-scale trials with a pilot trial and 151 full-scale trials without were identified from 47 meta-analyses. Trials with a pilot trial were published 0.9 years sooner (mean ± standard deviation: 1.7 ± 1.0 vs. 2.6 ± 2.0, P = 0.005) and in peer-reviewed journals with higher impact factors (60.9 ± 75.0 vs. 24.8 ± 50.3, P < 0.001). A pilot trial's presence was associated with lower risk of bias in full-scale trial random sequence generation (OR [95% CI]: 4.05 [1.27–12.91]), allocation concealment (2.89 [1.07–7.83]), and participants/researchers masking (4.31 [1.37–13.50]), but not outcome assessment masking (1.03 [0.49–2.18]), incomplete outcome data (1.27 [0.47–3.42]), and selective reporting (1.23 [0.44–3.46]). Conclusion: Conducting a pilot trial may enhance the quality of the subsequent full-scale trial.

Original languageEnglish (US)
Pages (from-to)117-125
Number of pages9
JournalJournal of Clinical Epidemiology
StatePublished - Aug 2023


  • Cochrane risk of bias assessment
  • Full-scale trial
  • Meta-research
  • Pilot trial
  • Randomized controlled trial
  • Trial quality

ASJC Scopus subject areas

  • Epidemiology


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