Time arrow in published clinical studies/trials indexed in MEDLINE: a systematic analysis of Retrospective vs Prospective study design, from 1960 to 2017.
- Published
- Accepted
- Subject Areas
- Bioinformatics, Clinical Trials, Epidemiology, Statistics, Data Mining and Machine Learning
- Keywords
- biological life, clinical trials, chronobiology, clinical study, disease, retrospective study, time variable, prospective study, MedLine, aging, demographic data., bibliometric study
- Copyright
- © 2018 Ciulla et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Time arrow in published clinical studies/trials indexed in MEDLINE: a systematic analysis of Retrospective vs Prospective study design, from 1960 to 2017. PeerJ Preprints 6:e27385v1 https://doi.org/10.7287/peerj.preprints.27385v1
Abstract
Clinical studies/trials are experiments or observations on human subjects considered by the scientific community the most appropriate instrument to answer specific research questions on interventions on health outcomes. The time-line of the observations might be focused on a single time point or to follow time, backward or forward, in the so called, respectively, retrospective and prospective study design. Since the retrospective approach has been criticized for the possible sources of errors due to bias and confounding, we aimed this study to assess if there is a prevalence of retrospective vs prospective design in the clinical studies/trials by querying MEDLINE. Our results on a sample of 1,438,872 studies/trials, (yrs 1960-2017), support a prevalence of retrospective, respectively 55% vs 45%. To explain this result, arandom sub-sample of studies where the country of origin was reported (n=1576) was categorized in high and low-income based onthe nominal Gross Domestic Product (GDP) and matched with the topic of the research. As expected, the absolute majority of studies/trials are carried on by high-income countries, respectively 86% vs 14%; even if a slight prevalence of retrospective was recorded in both income groups, nonetheless the most part of prospective studies are carried out by high-GDP countries, 85% vs 15%. Finally the differences in the design of the study are understandable when considering the topic of the research.
Author Comment
This is a submission to PeerJ for review.
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