Standardized difference in baseline characteristics of clinical trials: A meta-epidemiological study

Authors

  • Laura Durango Villada Universidad Pontificia Bolivariana, Colombia
  • Luz María Giraldo Echeverri Universidad Pontificia Bolivariana, Colombia
  • Ricardo Buitrago Bach Universidad Pontificia Bolivariana, Colombia
  • Jorge Hernando Donado Gómez Universidad Pontificia Bolivariana, Colombia

DOI:

https://doi.org/10.14482/sun.41.02.484.070

Keywords:

clinical trial, sample size, multivariate analysis, epidemiological study characteristics, statistical distributions

Abstract

Objective: Establish the difference between standardized mean for quantitative and qualitative variables, exploring its impact in randomized controlled clinical trials based on their sample size.

Methodology: Observational, meta-epidemiological study. Inclusion criteria involved parallel-group clinical trials published between January 2021 and August 2022 in four major medical journals worldwide. The exclusion criteria were the participation in clinical trials with more than two groups or arms.

Results: It was observed that 99 % of the studies included demographic variables (age, sex, race, or ethnicity), 98 % clinical variables, 45 % treatment-related variables, and 23 % social variables (educational level, marital status).

In the analysis of the standardized difference according to sample size, it was found that this value decreased as the number of participants increased, with a mean of 0,12 for the group with fewer than 500 participants and 0,02 for those groups with more than 2000 participants.

Conclusions: Studies with larger sample sizes exhibit a tinier standardized mean difference, showing a tendency to be inversely proportional. This finding suggests the importance of considering the sample size when interpreting the results of clinical trials, highlighting the relevance of the consistency and applicability of the findings in studies with extensive numbers of participants.

Author Biographies

  • Laura Durango Villada, Universidad Pontificia Bolivariana, Colombia

    Médica general, Universidad Pontificia Bolivariana, Medellín (Colombia). lauradurvil@gmail.com. https://orcid.org/0009-0003-5315-4847

  • Luz María Giraldo Echeverri, Universidad Pontificia Bolivariana, Colombia

    Médica general, Universidad Pontificia Bolivariana, Medellín (Colombia). medicinaluzmaria@gmail.com. https://orcid.org/0000-0001-5050-7238

  • Ricardo Buitrago Bach, Universidad Pontificia Bolivariana, Colombia

    Médico General, Universidad Pontificia Bolivariana, Medellín (Colombia). rbuitragob@gmail.com. https://orcid.org/0000-0002-6292-7018

  • Jorge Hernando Donado Gómez, Universidad Pontificia Bolivariana, Colombia

    Médico internista y epidemiólogo, Hospital Pablo Tobón Uribe. Profesor titular, Universidad Pontificia Bolivariana, Medellín (Colombia). jdonado@hptu.org.co. https://orcid.org/0000-0001-8581-2267

Published

2025-06-13

Issue

Section

ORIGINAL ARTICLE

How to Cite

Standardized difference in baseline characteristics of clinical trials: A meta-epidemiological study . (2025). SCIENTIFIC JOURNAL SALUD UNINORTE, 41(2), 467-488. https://doi.org/10.14482/sun.41.02.484.070

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