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

Abstract

ObjectivesEvidence 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 SettingWe 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. ResultsFifty-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]). ConclusionConducting a pilot trial may enhance the quality of the subsequent full-scale trial.