Ioannidis, J.; Collins, T. A.; Baas, J.

We aimed to evaluate how many authors are extremely productive and how their presence across countries and scientific fields has changed during 2000-2022. Extremely productive (EP) authors were defined as those with >60 full papers (articles, reviews, conference papers) published in a single calendar year and indexed in Scopus. We identified 3,191 EP authors across science excluding Physics and 12,624 EP authors in Physics. While Physics had much higher numbers of EP authors in the past, in 2022 the number of EP authors was almost similar in non-Physics and Physics disciplines (1,226 vs. 1,480). Excluding Physics, China had the largest number of EP authors, followed by the USA. However, the largest fold-wise increases between 2016 and 2022 were seen in Thailand (19-fold), Saudi Arabia (11.5-fold), Spain (11.5-fold), India (10.2-fold), Italy (6.9-fold), Russia (6.5-fold), Pakistan (5.7-fold), and South Korea (5.2-fold). Excluding Physics, most EP authors were in Clinical Medicine, but from 2016 to 2022 the largest relative increases were seen in Agriculture, Fisheries & Forestry (14.6-fold), Biology (13-fold), and Mathematics and Statistics (6.1-fold). EP authors accounted for 4,360 of the 10,000 most-cited authors (based on raw citation count) across science. While most EP Physics authors had modest citation impact in a composite citation indicator that adjusts for co-authorship and author positions, 67% of EP authors in non-Physics fields remained within the top-2% according to that indicator among all authors with >=5 full papers. Extreme productivity has become worryingly common across scientific fields with rapidly increasing rates in some countries and settings.