ArticleEuropean journal of medical research2022
Changing trends in clinical research literature on PubMed database from 1991 to 2020.
Article in European journal of medical research, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 23 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
23 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Major mistakes or errors in the use of trial sequential analysis in systematic reviews or meta-analyses - the METSA systematic review.BMC medical research methodology · 2024Pooled it
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- From Theory to Practice: GPT-Supported Data Extraction in Observational Studies on Transcatheter Aortic Valve Replacement.JACC. Advances · 2026Article
- Scientific education in German medical schools: nationwide cross-sectional study reveals student needs and gaps.BMC medical education · 2026Article
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- Contemporary spine research productivity: a bibliometric analysis of 28 orthopedic and neurosurgical journals.European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society · 2026Article
- Mapping Health Research Involving Human Subjects in Saudi Arabia:Saudi medical journal · 2026Article
- Assessing the risk of bias of clinical trials with large language models and ROBUST-RCT: a feasibility study.Scientific reports · 2026Article
- Bibliometric Analysis of Randomized Clinical Trials in the Philippines.Acta medica Philippina · 2026Article
- Streamlining evidence based clinical recommendations with large language models.NPJ digital medicine · 2025Article
- Article
- Perceptions of Japanese Medical Trainees and Physicians About Writing Case Reports: A Questionnaire-Based Survey.Cureus · 2025Article
- A century of cardiac rehabilitation research: Bibliometric review of publication history, keyword trends, and citations.NPJ cardiovascular health · 2025Article
- Cytogenetic annotation automation in myelodysplastic syndrome research databases.Blood advances · 2025Article
- Reviewing manuscripts for scientific journals: recommendations for early career scientists.BMC research notes · 2025Article
- Article
- A Systematic Review on the Impact of Vaccination for Respiratory Disease on Antibody Titer Responses, Health, and Performance in Beef and Dairy Cattle.Veterinary sciences · 2024Review
- Global mapping of randomized controlled trials in dentistry.Brazilian dental journal · 2024Article
- The applications of Australian-coded ICD-10 and ICD-10-AM data in research: A scoping review of the literature.Health information management : journal of the Health Information Management Association of Australia · 2024Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
7 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundClinical research publications have become the dominant source and basis of clinical evidence-based decision-making. Exploring the type and quantity of clinical research publications in the PubMed database is useful for clarifying the changing trends of clinical research development in recent years. Therefore, a longitudinal analysis of the type and quantity of clinical research publications in the PubMed database over three decades was conducted.
methodsThe PubMed database was searched to retrieve clinical research according to the type and year of publication from January 1, 1991 to December 31, 2020. The research types were classified as primary and secondary literature.
resultsA total of 1,078,404 primary literatures were retrieved and the constituent proportions were ranked from high to low as case report/series (27.54%), randomized clinical trials (RCTs) (23.62%), cohort studies (21.05%), cross-sectional studies (17.49%), case control studies (9.15%), non-RCTs (1.01%), and pragmatic clinical trials (PCTs) (0.15%). Correspondingly, 1,302,173 secondary literatures were retrieved and ranked as narrative review (70.88%), systematic review (15.02%), systematic review and meta-analyses (13.89%), traditional meta-analyses (4.48%), expert consensus (2.31%), guidelines (1.49%), scoping reviews (0.68%), net meta-analyses (0.40%), and umbrella reviews (0.04%). The average annual growth rate for the primary literature was 10.28%, and ranked from high to low as PCTs (83.68%), cohort studies (17.74%), cross-sectional studies (17.61%), non-RCTs (12.11%), case control studies (8.86%), RCTs (7.68%), case report/series (7.51%); while that for the secondary literature was 10.57%, and ranked from high to low as net meta-analyses (48.97%), umbrella reviews (47.09%), scoping reviews (41.92%), systematic reviews and meta-analyses (33.44%), systematic reviews (33.05%), traditional meta-analyses (12.49%), expert consensuses (9.22%), narrative review (8.72%), and guidelines (2.82%).
conclusionBoth the composition and number of clinical studies changed significantly from 1991 to 2020. Based on the trend, the case report/series, case control study, and narrative review are on the decline, while cohort study, cross-sectional study, systematic reviews, and systematic review and meta-analysis literature have increased. To improve the quality of clinical evidence, we recommend RCT and cohort study give priority to access to allocated research resources in future.
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Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.