The grateful scientist: what determines the presence of acknowledgements in randomised clinical trial publications?

Herm J. Lamberink, C.H. Vinkers, W.M. Otte, Joeri K. Tijdink

Research output: Contribution to JournalArticleAcademic


Randomised clinical trials (RCTs) are complex endeavours that demand
extensive collaborative eforts from researchers, institutions, and funding
partners. Undoubtedly, there is ample reason to acknowledge these eforts and
to be grateful for publication of the results. However, some RCTs explicitly
express gratitude in an acknowledgment section whereas other do not. We
hypothesized that this would be related to author’s gender and religion, medical
field, journal, and year of publication.

Quantitative analysis of all available full-text randomised clinical trials identified
through PubMed.

We determined the presence of an acknowledgment section containing explicit
words of gratitude in 90,163 full-text publications. The hypotheses were publicly pre-registered before study conduct. We tested the following determinants of the presence of these acknowledgment sections: gender of the first and last author, the percentage of protestant inhabitants in the country of the primary research institution, the year of publication, journal impact factor (JIF), the journal’s medical field (compared to the medical field of surgery). Explorative analyses were performed on the diferent determinants that were associated with received gratitude in the acknowledgement sections.

Main outcome measure
The presence of an acknowledgment section with explicit words of gratitude.

In total, 28,897 (32%) RCT publications contained an acknowledgement section
with explicit words of gratitude. All hypotheses were confirmed, with a higher
likelihood of an acknowledgement section with words of gratitude when the first
and/or last author was female (OR 1.28 95% CI 1.24-1.31), an increased
percentage of protestant inhabitants in the country of the first author’s afliation
(+ 10%; OR = 1.04 95% CI 1.04-1.05), and more recent publication (+ 1 year; OR
1.04 95% CI 1.04-1.05). The journal’s impact factor (- 1 JIF; OR = 0.99 95% CI
0.99-0.99) and RCTs published in surgical journals (OR 0.35 95% CI 0.32-0.38)
were associated with a lower likelihood of RCT publications containing words of

Acknowledgement sections with explicit words of gratefulness are more
frequently present when researchers are female, from protestant countries,
working in non-surgical fields, and published in lower impact factor journals, and this trend has increased over time. To foster a healthy and responsible
publication culture, it is important that all individuals, institutions, and groups
that have contributed to the research are acknowledged. Credit should go where
credit is due, and Christmas is the most suitable period to remind us of the
importance of gratitude.
Original languageEnglish
Pages (from-to)1-23
Number of pages23
Publication statusPublished - 25 Dec 2018


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