New York, NY (October 27, 2026) — Months after a Columbia University School of Nursing-led audit published in the Lancet reported thousands of fabricated citations emerged in medical papers, the same research team has found the same problem in the physical sciences, engineering, and computing.
About 1 in 435 science and engineering papers from 2026 cite studies that cannot be found online, up from 1 in 1,600 in 2023. While relatively few papers were affected, fabricated references were identified across every discipline examined: 25.6 per 10,000 papers in physics, 18.4 in materials science, 11.1 in computer science and artificial intelligence, 10.3 in engineering, and 4.3 in chemistry.
The study, “Evaluation of possibly fabricated references in 500,000 science, engineering, and computing papers,” was published on October 26, 2026 in the Proceedings of the National Academy of Sciences (PNAS) and is part of a body of research made available this year by the team, examining this problem.
A Lancet research letter in May, the first, identified 4,046 fabricated citations in 2,810 of 2.5 million medical papers. A July paper in the Journal of Internal Medicine reported fabricated references were about twice as common in medRxiv preprints as in peer-reviewed articles (37.2 versus 16.4 per 10,000). And a September arXiv preprint from the team, not yet peer reviewed, found 26 large language models fabricated 55% of the medical references they were asked to supply.
“After our Lancet audit, the question we heard most often was whether this was a problem particular to medicine. It is not,” says Maxim Topaz, PhD, associate professor at Columbia Nursing and Columbia University Data Science Institute, who led the PNAS study.
“A reference is a promise to the reader that a source exists. In a growing number of papers across the sciences, that promise is not being kept.”
Other authors of the PNAS study include Pallavi Gupta, PhD, and Zhihong Zhang, PhD, Columbia University School of Nursing; and Laura-Maria Peltonen, PhD, Department of Health and Social Management, University of Eastern Finland; Wellbeing Services County of North Savo; Wellbeing Services County of Southwest Finland; and Department of Nursing Science, University of Turku.
The audit reveals a small but accelerating problem
The researchers analyzed 500,000 papers in chemistry, physics, materials science, engineering, and computer science published from January 2023 through March 2026, drawn from OpenAlex, a large database of scholarly works. An automated verification tool checked the 21.6 million references that carried a digital object identifier (DOI). It classified 1,135 references across 619 papers as fabricated when the cited title could not be found in online databases. When two independent experts reviewed a random sample of 400 flagged references, they confirmed 85.8% were fabricated. The share of papers affected rose from 1 in 1,600 papers (6.3 per 10,000) in 2023 to 1 in 650 (15.4 per 10,000) in 2025 and 1 in 435 (23.0 per 10,000) in the first quarter of 2026.
Most affected papers contained one or two fabricated references. But 27 papers contained five or more, and those 27 accounted for more than a third of all fabricated references identified. Applying each field’s rate to the approximately 7 million papers in these fields over the same period, the authors estimate that about 8,500 published papers carry at least one fabricated reference. At the time of the audit, two of the 619 affected papers had been retracted.
“A paper with one unverifiable reference and a paper with five or more are not the same thing, and editors should not treat them the same way,” Topaz says.
“The encouraging part is that this is one of the few integrity problems that can be checked automatically, before a paper is ever published.”
The authors recommend routine automated reference checks at submission, together with retroactive screening of the published literature. They also recommend that indexing services and research-integrity databases record fabricated references as a distinct category, separate from plagiarism or data falsification, so that they can be tracked and acted on.
What’s next in the pipeline
As a next step, the researchers are screening up to 12 million medical papers published since 2020 and have experts grade how much several hundred of the fabricated references affect the papers that cite them. Working with journal editors and research integrity officers, they will use the findings to develop screening protocols, policies, and trainings for journal submissions.
This new project, “Fabricated Citations in the Biomedical Literature: Measuring Prevalence, Triaging Evidentiary Impact, and Reducing Response Burden,” is supported by award ORIIR260088 from the Office of the Assistant Secretary for Health (OASH), U.S. Department of Health and Human Services (HHS), as part of a financial assistance award totaling $249,999 with 100 percent funded by OASH/HHS. (The contents are solely the responsibility of the authors and do not necessarily represent the official views of, nor an endorsement by, OASH, HHS, or the U.S. Government.)
