Is There Evidence of P-Hacking in Imaging Research?

BACKGROUND

P-hacking, the tendency to run selective analyses until they become significant, is prevalent in many scientific disciplines.

PURPOSE

This study aims to assess if p-hacking exists in imaging research.

METHODS

Protocol, data, and code available here https://osf.io/xz9ku/?view_only=a9f7c2d841684cb7a3616f567db273fa. We searched imaging journals Ovid MEDLINE from 1972 to 2021. Text mining using Python script was used to collect metadata: journal, publication year, title, abstract, and P-values from abstracts. One P-value was randomly sampled per abstract. We assessed for evidence of p-hacking using a p-curve, by evaluating for a concentration of P-values just below .05. We conducted a one-tailed binomial test (α = .05 level of significance) to assess whether there were more P-values falling in the upper range (e.g., .045 < P < .05) than in the lower range (e.g., .04 < P < .045). To assess variation in results introduced by our random sampling of a single P-value per abstract, we repeated the random sampling process 1000 times and pooled results across the samples. Analysis was done (divided into 10-year periods) to determine if p-hacking practices evolved over time.

RESULTS

Our search of 136 journals identified 967,981 abstracts. Text mining identified 293,687 P-values, and a total of 4105 randomly sampled P-values were included in the p-hacking analysis. The number of journals and abstracts that were included in the analysis as a fraction and percentage of the total number was, respectively, 108/136 (80%) and 4105/967,981 (.4%). P-values did not concentrate just under .05; in fact, there were more P-values falling in the lower range (e.g., .04 < P < .045) than falling just below .05 (e.g., .045 < P < .05), indicating lack of evidence for p-hacking. Time trend analysis did not identify p-hacking in any of the five 10-year periods.

CONCLUSION

We did not identify evidence of p-hacking in abstracts published in over 100 imaging journals since 1972. These analyses cannot detect all forms of p-hacking, and other forms of bias may exist in imaging research such as publication bias and selective outcome reporting.

Association of Accuracy, Conclusions, and Reporting Completeness With Acceptance by Radiology Conferences and Journals

BACKGROUND

Preferential publication of studies with positive findings can lead to overestimation of diagnostic test accuracy (i.e. publication bias). Understanding the contribution of the editorial process to publication bias could inform interventions to optimize the evidence guiding clinical decisions.

PURPOSE/HYPOTHESIS

To evaluate whether accuracy estimates, abstract conclusion positivity, and completeness of abstract reporting are associated with acceptance to radiology conferences and journals.

STUDY TYPE

Meta-research.

POPULATION

Abstracts submitted to radiology conferences (European Society of Gastrointestinal and Abdominal Radiology (ESGAR) and International Society for Magnetic Resonance in Medicine (ISMRM)) from 2008 to 2018 and manuscripts submitted to radiology journals (Radiology, Journal of Magnetic Resonance Imaging [JMRI]) from 2017 to 2018. Primary clinical studies evaluating sensitivity and specificity of a diagnostic imaging test in humans with available editorial decisions were included.

ASSESSMENT

Primary variables (Youden's index [YI > 0.8 vs. <0.8], abstract conclusion positivity [positive vs. neutral/negative], number of reported items on the Standards for Reporting of Diagnostic Accuracy Studies [STARD] for Abstract guideline) and confounding variables (prospective vs. retrospective/unreported, sample size, study duration, interobserver agreement assessment, subspecialty, modality) were extracted.

STATISTICAL TESTS

Multivariable logistic regression to obtain adjusted odds ratio (OR) as a measure of the association between the primary variables and acceptance by radiology conferences and journals; 95% confidence intervals (CIs) and P-values were obtained; the threshold for statistical significance was P < 0.05.

RESULTS

A total of 1000 conference abstracts (500 ESGAR and 500 ISMRM) and 1000 journal manuscripts (505 Radiology and 495 JMRI) were included. Conference abstract acceptance was not significantly associated with YI (adjusted OR = 0.97 for YI > 0.8; CI = 0.70-1.35), conclusion positivity (OR = 1.21 for positive conclusions; CI = 0.75-1.90) or STARD for Abstracts adherence (OR = 0.96 per unit increase in reported items; CI = 0.82-1.18). Manuscripts with positive abstract conclusions were less likely to be accepted by radiology journals (OR = 0.45; CI = 0.24-0.86), while YI (OR = 0.85; CI = 0.56-1.29) and STARD for Abstracts adherence (OR = 1.06; CI = 0.87-1.30) showed no significant association. Positive conclusions were present in 86.7% of submitted conference abstracts and 90.2% of journal manuscripts.

DATA CONCLUSION

Diagnostic test accuracy studies with positive findings were not preferentially accepted by the evaluated radiology conferences or journals.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

[Citation misuse and its effects on public health]

In order to effectively contribute to scientific knowledge, biomedical observations have to be validated and debated by scientists in the relevant field. Along this debate that mainly takes place in the scientific literature, citation of previous studies plays a major role. However, only a few academic studies have quantitatively evaluated the suitability and accuracy of scientific citations. Here we review these academic studies. Two types of misuse have been pointed out: Citation bias and citation distortion. First, scientific citations favor positive results and those supporting authors' conclusion. Second, many statements linked to a reference actually misrepresent the referenced findings. About 10% of all citations in biomedicine are strongly inaccurate and misleading for the reader. Finally, we give two examples illustrating how some citation misuses do affect public health: The opioid crisis in the USA and the unjustified fostering of hydroxychloroquine for Covid-19 treatment in France.

Mapping the scientific research on radiology departments: Global trends in publication, collaboration and trending topics

PURPOSE

To characterize the global research trend in radiology departments based on bibliometric indicators.

MATERIAL AND METHOD

As a source of information, Science Citation Index Expanded and Journal Citation Reports from Web of Science Core Collection (WoSCC) were used. Annual trends, journals of publication, subject categories of journals, collaboration indexes between authors and institutions, network of cowords and most cited papers were identified and analysed. The period of study was 2009-2018.

RESULTS

283,587 downloaded papers were analysed. The number of articles was increasing, as well as the percentage of funded works. Papers were published in 7314 different journals, being the most productive Plos One (5077), followed by American Journal of Roentgenology (4602) and European Radiology (3644). Most productive subject categories of journals were Radiology, Nuclear Medicine & Medical Imaging (86,568 papers), Clinical Neurology (29,722) and Surgery (23,564). International collaboration has increased more than 5 points, from 15.2% in 2009 to 20.7% in 2018.

CONCLUSIONS

Most cited articles were published in high impact journals outside the scope of diagnostic imaging. Most influential topics included technical innovations within imaging modalities. MRI replaced conventional radiography and CT as the imaging technique of choice in imaging research.

Tweeting Bias in Diagnostic Test Accuracy Research: Does Title or Conclusion Positivity Influence Dissemination?

PURPOSE

To examine if tweeting bias exists within imaging literature by determining if diagnostic test accuracy (DTA) studies with positive titles or conclusions are tweeted more than non-positive studies.

METHODS

DTA studies published between October 2011 to April 2016 were included. Positivity of titles and conclusions were assessed independently and in duplicate, with disagreements resolved by consensus. A negative binomial regression analysis controlling for confounding variables was performed to assess the relationship between title or conclusion positivity and tweets an article received in the 100 days post-publication.

RESULTS

354 DTA studies were included. Twenty-four (7%) titles and 300 (85%) conclusions were positive (or positive with qualifier); 1 (0.3%) title and 23 (7%) conclusions were negative; and 329 (93%) titles and 26 (7%) conclusions were neutral. Studies with positive, negative, and neutral titles received a mean of 0.38, 0.00, and 0.45 tweets per study; while those with positive, negative, and neutral conclusions received a mean of 0.44, 0.61, and 0.38 tweets per study. Regression coefficients were -0.05 (SE 0.46) for positive relative to non-positive titles, and -0.09 (SE 0.31) for positive relative to non-positive conclusions. The positivity of the title (P = 0.91) or conclusion (P = 0.76) was not significantly associated with the number of tweets an article received.

CONCLUSIONS

The positivity of the title or conclusion for DTA studies does not influence the amount of tweets it receives suggesting that tweet bias is not present among imaging diagnostic accuracy studies. Study protocol available at https://osf.io/hdk2m/.

Publication bias in diagnostic imaging: conference abstracts with positive conclusions are more likely to be published

OBJECTIVE

To evaluate whether imaging diagnostic test accuracy conference abstracts with positive conclusions or titles are more likely to reach full-text publication than those with negative (or neutral) conclusions or titles.

METHODS

Diagnostic accuracy research abstracts were included if they were presented at the 2011 or 2012 Radiological Society of North America conference. Full-text publication status at 5 years post conference abstract submission was determined. Conclusion and title positivity of conference abstracts were extracted, as well as potential confounding factors. The associations of conclusion and title positivity with publication status at 5 years post conference abstract submission were assessed using a multivariable logistic regression model. Conditional odds ratios were calculated to express the strength of associations, adjusting for the confounders.

RESULTS

In total, 282/400 (71%) of included conference abstracts reached full-text publication. A total of 246 out of 337 (74%) conference abstracts with positive conclusions resulted in full-text publications, compared with 26/48 (54%) with neutral conclusions and 5/15 (33%) with negative conclusions. In multivariable logistic regression, conclusion positivity was significantly associated with full-text publication (odds ratio 3.6; 95% CI 1.9-6.7 for conference abstracts with positive conclusions, compared with those with non-positive conclusions); this did not apply to title positivity (odds ratio 1.2; 95% CI 0.47-3.0).

CONCLUSION

Imaging conference abstracts with positive conclusions were more likely to be published as full-text articles. Title positivity was not associated with publication. This preferential publication pattern may lead to an overrepresentation of positive studies in the literature. An overrepresentation of positive studies may contribute to inflated estimates of test accuracy and has the potential to adversely influence patient care.

KEY POINTS

• Imaging diagnostic test accuracy conference abstracts with positive conclusions were more likely to be reported as full-text articles than those with non-positive conclusions. • The majority (75%) of imaging diagnostic test accuracy conference abstracts with positive conclusions were published, compared with only 53% and 33% with neutral and negative conclusions, respectively. • Conclusion positivity remained associated with the full-text publication of conference abstracts when controlling for multiple potential confounding variables.

Who? What? Where? A snapshot of Nuclear Medicine Research Presentations from recent ANZSNM conferences in Australia and New Zealand

OBJECTIVES

The aims of this study were to: 1) discover location (by city) of contributors to poster and oral presentations at recent ANZSNM conferences; 2) determine the nuclear medicine themes most commonly explored; 3) establish institutions producing the highest number of oral and poster abstracts and 4) determine publication rates of conference abstracts to full papers from recent ANZSNM conferences.

METHODS

Retrospective analysis of abstracts published in the Internal Medicine Journal Special Issues 2014-2019 identified 614 abstracts. Invited plenary speaker abstracts were excluded. Descriptive statistics were used in data analysis. Conference abstracts were analysed using the following criteria: poster or oral presentation, author/s, city location, hospital and subject matter. Themes defined by the ANZSNM conference committee for abstract submission were: cardiology, oncology, neurology, therapy, renal/urology, gastrointestinal, paediatrics, musculoskeletal, infection/inflammation, technology, physics, radiation safety, radiopharmacy/radiochemistry, education, or general. Retrospective analysis of 555 conference abstracts (excluding New Zealand and International, 59 abstracts) using Google Scholar, Pubmed and Google databases was undertaken. Abstract titles, key words, institutions and/or authors' names were used to find peer-reviewed papers. Identified papers were authenticated through either open access, publicly available author information or Monash University's library access. Published paper citations were also recorded (up to 1st July 2019).

RESULTS

Analysis of 614 abstracts 2014 - 2019 was performed. Over five years, the average number of poster abstracts was 67.8 and oral 55.0. Sydney submitted the highest number of poster abstracts, while Melbourne the highest number of oral abstracts. Most popular abstract theme was oncology for both poster and oral abstracts. Publications found had in excess of 1250 citations.One hundred and one publications from one hundred and seven conference presentations were identified, distributed across sixty journals. Conference presentation to full publication rate was 18.2%; excluding 2019 conference abstracts the rate was 21.5%.

CONCLUSION

Publishing research findings is a challenging process. A retrospective analysis of research presented at recent ANZSNM conferences by abstract content was undertaken, with conference presentation to full publication rate found to be at the lower end of reported literature findings.