The REPRISE project: protocol for an evaluation of REProducibility and Replicability In Syntheses of Evidence

Large language models for conducting systematic reviews: on the rise, but not yet ready for use-a scoping review

BACKGROUND AND OBJECTIVES

Machine learning promises versatile help in the creation of systematic reviews (SRs). Recently, further developments in the form of large language models (LLMs) and their application in SR conduct attracted attention. We aimed at providing an overview of LLM applications in SR conduct in health research.

METHODS

We systematically searched MEDLINE, Web of Science, IEEEXplore, ACM Digital Library, Europe PMC (preprints), Google Scholar, and conducted an additional hand search (last search: February 26, 2024). We included scientific articles in English or German, published from April 2021 onwards, building upon the results of a mapping review that has not yet identified LLM applications to support SRs. Two reviewers independently screened studies for eligibility; after piloting, 1 reviewer extracted data, checked by another.

RESULTS

Our database search yielded 8054 hits, and we identified 33 articles from our hand search. We finally included 37 articles on LLM support. LLM approaches covered 10 of 13 defined SR steps, most frequently literature search (n = 15, 41%), study selection (n = 14, 38%), and data extraction (n = 11, 30%). The mostly recurring LLM was Generative Pretrained Transformer (GPT) (n = 33, 89%). Validation studies were predominant (n = 21, 57%). In half of the studies, authors evaluated LLM use as promising (n = 20, 54%), one-quarter as neutral (n = 9, 24%) and one-fifth as nonpromising (n = 8, 22%).

CONCLUSION

Although LLMs show promise in supporting SR creation, fully established or validated applications are often lacking. The rapid increase in research on LLMs for evidence synthesis production highlights their growing relevance.

PLAIN LANGUAGE SUMMARY

Systematic reviews are a crucial tool in health research where experts carefully collect and analyze all available evidence on a specific research question. Creating these reviews is typically time- and resource-intensive, often taking months or even years to complete, as researchers must thoroughly search, evaluate, and synthesize an immense number of scientific studies. For the present article, we conducted a review to understand how new artificial intelligence (AI) tools, specifically large language models (LLMs) like Generative Pretrained Transformer (GPT), can be used to help create systematic reviews in health research. We searched multiple scientific databases and finally found 37 relevant articles. We found that LLMs have been tested to help with various parts of the systematic review process, particularly in 3 main areas: searching scientific literature (41% of studies), selecting relevant studies (38%), and extracting important information from these studies (30%). GPT was the most commonly used LLM, appearing in 89% of the studies. Most of the research (57%) focused on testing whether these AI tools actually work as intended in this context of systematic review production. The results were mixed: about half of the studies found LLMs promising, a quarter were neutral, and one-fifth found them not promising. While LLMs show potential for making the systematic review process more efficient, there is still a lack of fully tested and validated applications. However, the increasing number of studies in this field suggests that these AI tools are becoming increasingly important in creating systematic reviews.

A worldwide itinerary of research ethics in science for a better social responsibility and justice: a bibliometric analysis and review

This study provides a comprehensive overview of research ethics in science using an approach that combine bibliometric analysis and systematic review. The importance of ethical conduct in scientific research to maintain integrity, credibility, and societal relevance has been highlighted. The findings revealed a growing awareness of ethical issues, as evidenced by the development of numerous guidelines, codes of conduct, and oversight institutions. However, significant challenges persist, including the lack of standardized approaches for detecting misconduct, limited understanding of the factors contributing to unethical behavior, and unclear definitions of ethical violations. To address these issues, this study recommends promoting transparency and data sharing, enhancing education, and training programs, establishing robust mechanisms to identify and address misconduct, and encouraging collaborative research and open science practices. This study emphasizes the need for a collaborative approach to restore public confidence in science, protect its positive impact, and effectively address global challenges, while upholding the principles of social responsibility and justice. This comprehensive approach is crucial for maintaining research credibility, conserving resources, and safeguarding both the research participants and the public.

Charting the therapeutic landscape: a comprehensive evidence map on medical cannabis for health outcomes

The therapeutic potential of medical cannabis has garnered significant attention in recent years, prompting an urgent need for a comprehensive understanding of its effectiveness across various health outcomes. This article presents an Evidence Map that systematically summarizes clinical evidence on the use of medical cannabis, including the health conditions it addresses, the interventions employed, and the resulting clinical outcomes. The objective is to map the effectiveness of medical cannabis in relation to a wide range of health outcomes. The systematic review process involved two independent, blinded literature researchers who screened the search output using Rayyan software. For studies deemed relevant, full texts were obtained to clarify inclusion or exclusion criteria, and any disagreements were resolved through group discussion. Out of 1,840 initial references, 279 potential studies were selected and read in full, resulting in the inclusion of 194 studies in this evidence map. The results highlight the use of various cannabis formulations, including those based on isolated cannabidiol (CBD). Seventy-one distinct health outcomes were identified in the systematic reviews, with the most reported outcomes being related to various types of pain and patient safety. Other frequently studied outcomes included appetite regulation, chemotherapy-induced nausea and vomiting, and muscle spasticity. Notably, 278 out of 489 descriptions of treatment effects for these health outcomes reported either "Positive" or "Potentially Positive" effects. When considering only high-quality systematic reviews, as evaluated by the AMSTAR 2 tool, 42 out of 67 descriptions of treatment effects for up to 20 health outcomes were classified as "Positive" or "Potentially Positive." These outcomes included pain, insomnia, seizures, anxiety, muscle spasticity, multiple sclerosis, urinary incontinence, anorexia, and patient safety. This evidence map provides a comprehensive overview of the current clinical evidence on medical cannabis, highlighting its potential therapeutic benefits across a range of health conditions and emphasizing the need for further high-quality research.

Reporting of adverse events of treatment interventions in multiple myeloma: an overview of systematic reviews

The present study is an overview of systematic reviews focusing on adverse events of antimyeloma treatments. It provides a systematic description of adverse events as they are reported in the systematic reviews as well as a critical appraisal of included reviews. We conducted a comprehensive literature search in the most widely used electronic databases looking for systematic reviews that had an adverse event of an antimyeloma treatment intervention as primary outcome. Two independent reviewers conducted selection of included studies and data extraction on predesigned online forms and assessed study quality using AMSTAR 2. Overall corrected covered area (CCA) was calculated to examine the overlap of primary studies across systematic reviews. After screening eligible studies, 23 systematic reviews were included in this overview. Seven reviews with overall CCA of 14.7% examined cardiovascular adverse events of different drugs, including immunomodulatory drugs and proteasome inhibitors (mainly carfilzomib). Nine focused on infections, presenting with overall CCA of 5.8%, each one focused on a different drug or drug class. Three studied thromboembolism in patients treated either with lenalidomide, any immunomodulatory drug, or with daratumumab and had an overall CCA equal to 1.5%. Four more reviews focused on bortezomib-associated neurotoxicity, carfilzomib-associated renal toxicity, or second primary malignancies as an adverse event of lenalidomide or anti-CD38 monoclonal antibody treatment. The quality of included studies as judged by AMSTAR 2 was mostly critically low. Absence of a priori registered protocol and formal assessment of risk of bias of included primary studies were the most common shortcomings. Reporting of antimyeloma drug-associated toxicity is supported by multiple systematic reviews; nevertheless, methodological quality of existing reviews is mostly low.

Development and Evaluation of a Framework for Identifying and Addressing Spin for Harms in Systematic Reviews of Interventions

"Spin" refers to misleading reporting, interpretation, and extrapolation of findings in primary and secondary research (such as in systematic reviews). The study of spin primarily focuses on beneficial outcomes. The objectives of this research were threefold: first, to develop a framework for identifying spin associated with harms in systematic reviews of interventions; second, to apply the framework to a set of reviews, thereby pinpointing instances where spin may be present; and finally, to revise the spin examples, offering guidance on how spin can be rectified.

The authors developed their framework through an iterative process that engaged an international group of researchers specializing in spin and reporting bias. The framework comprises 12 specific types of spin for harms, grouped by 7 categories across the 3 domains (reporting, interpretation, and extrapolation). The authors subsequently gathered instances of spin from a random sample of 100 systematic reviews of interventions. Of the 58 reviews that assessed harm and the 42 that did not, they found that 28 (48%) and 6 (14%), respectively, had at least 1 of the 12 types of spin for harms. Inappropriate extrapolation of the results and conclusions for harms to populations, interventions, outcomes, or settings not assessed in a review was the most common category of spin in 17 of 100 reviews.

The authors revised the examples to remove spin, taking into consideration the context (for example, medical discipline, source population), findings for harms, and methodological limitations of the original reviews. They provide guidance for authors, peer reviewers, and editors in recognizing and rectifying or (preferably) avoiding spin, ultimately enhancing the clarity and accuracy of harms reporting in systematic review publications.

The Reality of Tonic Immobility in Victims of Sexual Violence: "I was Paralyzed, I Couldn't Move"

Tonic immobility (TI) is a state of temporary, involuntary motor inhibition that occurs in states of intense fear and has been studied among victims of sexual violence. Studies on TI are scarce and mainly focus on rape victims. The present study is a literature review of research that has examined TI in women victims of sexual violence. A database search was carried out using the Preferred data elements for systematic reviews and meta-analyses (PRISMA) method. In order to be included in the analysis, the manuscripts had to deal exclusively with research involving samples of subjects and the study analyzed TI in victims of sexual violence. In all, 11 manuscripts met the above criteria and were included in the review. Research describes that TI is characterized by two factors: fear and immobility. Quantitative research was conclusive in affirming the presence of a state of paralysis and fear in TI. The immobility factor is the determining factor in explaining the victim's lack of defense or resistance and causes effects such as trembling, physical and mental paralysis, inability to vocalize, and eye closure. In addition, TI has been correlated with long-term negative clinical manifestations as victims are more likely to suffer from post-traumatic stress disorder. These findings contribute to an understanding of TI in victims of sexual violence. Therefore, legal and care practitioners must be able to recognize TI to understand the victim's behavior, differentiate it from consent, and to be able to assist in their recovery.

Association between ultra-processed foods consumption and the risk of hypertension: An umbrella review of systematic reviews

BACKGROUND

Several systematic reviews (SRs) have investigated the association between ultra-processed foods (UPFs) and the risk of hypertension in various populations. However, the quality of the evidence remains unclear. This umbrella review was thus conducted to fill this gap.

METHODS

We searched for SRs with and without meta-analyses comparing high UPF versus low UPF consumption on the risk of hypertension in the Cochrane Library, Embase, PubMed, and Web of Science from inception to August 2022. This study was registered in PROSPERO (No. CRD42022352934). The A MeaSurement Tool to Assess systematic Reviews 2 (AMSTAR-2) tool and the Preferred Reporting Item for Systematic Review and Meta-analysis 2009 (PRISMA 2009) statement were used to evaluate the methodological and reporting quality of the included SRs. Stata 15/SE was used to reanalyse the data using the random-effects model, and the risk of bias of observational studies from included SRs was reassessed using the Newcastle-Ottawa Scale (NOS) tool. The certainty of the evidence body was assessed using the GRADE recommendation.

RESULTS

Seven SRs were included in the umbrella review. Among them, nine observational studies (5 cross-sectional and 4 cohort studies), whose available data were resynthesised using meta-analysis. The methodological and reporting quality of the included SRs were relatively poor. The meta-analysis results revealed suggestive evidence of an association between high UPF consumption and the incidence of hypertension (odds ratio: 1.23, 95% confidence interval: 1.11 to 1.37, p < 0.001, 95% prediction interval: 0.92 to 1.64, critically low certainty) compared to low UPF consumption.

CONCLUSION

High UPF consumption is associated with an increased risk of hypertension. However, well-conducted SRs, including high-quality prospective cohort studies, are needed to further verify these findings.

Patient With Parkinson Disease and Care Partner Perceptions of Key Domains Affecting Health-Related Quality of Life: Systematic Review

BACKGROUND AND OBJECTIVES

To effectively customize Parkinson disease (PD) programs, it is important to incorporate the "individual's voice" and have a thorough understanding of the symptom priorities of people with PD (PwP) and care partners (CP). In this convergent integrated mixed-method systematic review, we aimed to analyze qualitative and quantitative evidence of PD motor and nonmotor symptoms affecting health-related quality of life (HRQOL) in PwP and CP, comparing priorities across different levels of disease severity.

METHODS

We searched MEDLINE, PsycINFO, Web of Science, Embase, and Scopus; ProQuest Dissertations and Theses Global; and the Michael J. Fox Foundation Data Resources for studies published up to June 29, 2022. We included qualitative, quantitative, and mixed-method studies investigating PD symptom priorities among PwP and CP. We critically appraised eligible studies for methodological quality using the Mixed-Methods Appraisal Tool. Derived terms were mapped and coded according to thematic attribution. Independent syntheses of qualitative and quantitative evidence and transformation of quantitative data into qualitative formats were performed.

RESULTS

Of the 7,716 identified studies, we included 70 that provided qualitative (n = 13), quantitative (n = 53), and mixed (n = 4) evidence. We included 604 mapped terms representing 11 PwP-identified and CP-identified motor and nonmotor symptom categories. Across all PD stages, both PwP and CP considered 5 domains more affecting their HRQOL, namely: "motor functionality," "mood," "cognition," "gait, balance, posture, and falls," and "nighttime sleep disorders." In early disease, PwP and CP considered "mood" the domain that most affected their HRQOL. In advanced PD, PwP considered "pain" the domain that most affects their HRQOL, while CP considered "psychiatric symptoms." The domain "gait, balance, posture, and falls" was equally considered by both PwP and CP as the second domain that most affects their HRQOL in the advanced stage of PD.

DISCUSSION

The ranking of the priority of symptoms is largely shared by PwP and CP, and motor symptom priorities dominate the full disease spectrum. However, the nonmotor symptom priorities shift according to the disease severity stage. Tailored care and research require that providers consider these shifting priorities and incorporate the "individual's voice" into treatment decisions.

Quality of systematic reviews with meta-analyses of resveratrol: A methodological systematic review

Recently, several meta-analyses (MAs) have focused on the health effects of resveratrol. However, the methodological and reporting quality of these MAs has not yet been fully evaluated so far. Therefore, the present study evaluated the quality of these MAs through a methodological systematic review. Systematic searches were conducted in PubMed, Embase, Web of Science, and Cochrane Library from inception until May 20, 2022, and PubMed was used to update the search until September 6, 2023. The methodological and reporting quality of the selected MAs was evaluated using AMSTAR-2 and PRISMA 2009. Fifty-one MAs published during 2013-2023 were included. In each review, the number of primary studies ranged from 3 to 37, and the number of participants ranged from 50 to 2114. Among the first-listed primary outcomes, only 23 (45.10%) were "positive." As for the methodological quality, most MAs (44, 86.27%) on resveratrol were rated critically low. Inadequate reporting of the included MAs mainly involved items 2 ("Structured summary"), 5 ("Protocol and registration"), 8 ("Search"), 9 ("Study selection"), 10 ("Data collection process"), 12 ("Risk of bias in individual studies"), and 24 ("Summary of evidence") based on the PRISMA 2009. Additionally, journal's impact factor, number of authors, and funding support were positively associated with the overall methodological quality but were not statistically significant (p > 0.05). Future MAs on resveratrol require better design, implementation, and reporting by following the Cochrane Handbook, AMSTAR-2, and PRISMA.

The 2-week systematic review (2weekSR) method was successfully blind-replicated by another team: a case study

OBJECTIVE

To assess the replicability of a 2-week systematic review (index 2weekSR) created with the assistance of automation tools using the fidelity method.

METHODS

A Preferred Reporting Items for Systematic reviews and Meta-Analyses compliant SR protocol was developed based on the published information of the index 2weekSR study. The replication team consisted of three reviewers. Two reviewers blocked off time during the replication. The total time to complete tasks and the meta-analysis results were compared with the index 2weekSR study. Review process fidelity scores (FSs) were calculated for review methods and outcomes. Barriers to completing the replication were identified.

RESULTS

The review was completed over 63 person-hours (11 workdays/15 calendar days). A FS of 0.95 was achieved for the methods, with 3 (of 8) tasks only partially replicated, and an FS of 0.63 for the outcomes, with 6 (of 7) only partially replicated and one task was not replicated. Nonreplication was mainly caused by missing information in the index 2weekSR study that was not required in standard reporting guidelines. The replication arrived at the same conclusions as the original study.

CONCLUSION

A 2weekSR study was replicated by a small team of three reviewers supported by automation tools. Including additional information when reporting SRs should improve their replicability.

Definition, harms, and prevention of redundant systematic reviews

BACKGROUND

Along with other types of research, it has been stated that the extent of redundancy in systematic reviews has reached epidemic proportions. However, it was also emphasized that not all duplication is bad, that replication in research is essential, and that it can help discover unfortunate behaviors of scientists. Thus, the question is how to define a redundant systematic review, the harmful consequences of such reviews, and what we could do to prevent the unnecessary amount of this redundancy.

MAIN BODY

There is no consensus definition of a redundant systematic review. Also, it needs to be defined what amount of overlap between systematic reviews is acceptable and not considered a redundancy. One needs to be aware that it is possible that the authors did not intend to create a redundant systematic review. A new review on an existing topic, which is not an update, is likely justified only when it can be shown that the previous review was inadequate, for example, due to suboptimal methodology. Redundant meta-analyses could have scientific, ethical, and economic questions for researchers and publishers, and thus, they should be avoided, if possible. Potential solutions for preventing redundant reviews include the following: (1) mandatory prospective registration of systematic reviews; (2) editors and peer reviewers rejecting duplicate/redundant and inadequate reviews; (3) modifying the reporting checklists for systematic reviews; (4) developing methods for evidence-based research (EBR) monitoring; (5) defining systematic reviews; (6) defining the conclusiveness of systematic reviews; (7) exploring interventions for the adoption of methodological advances; (8) killing off zombie reviews (i.e., abandoned registered reviews); (9) better prevention of duplicate reviews at the point of registration; (10) developing living systematic reviews; and (11) education of researchers.

CONCLUSIONS

Disproportionate redundancy of the same or very similar systematic reviews can lead to scientific, ethical, economic, and societal harms. While it is not realistic to expect that the creation of redundant systematic reviews can be completely prevented, some preventive measures could be tested and implemented to try to reduce the problem. Further methodological research and development in this field will be welcome.

Impact of searching clinical trials registers in systematic reviews of pharmaceutical and non-pharmaceutical interventions: Reanalysis of meta-analyses

Systematic reviewers are advised to search trials registers to minimise risk of reporting biases. However, there has been little research on the impact of searching trials registers on the results of meta-analyses. We aimed to evaluate the impact of searching clinical trials registers for systematic reviews of pharmaceutical or non-pharmaceutical interventions. We searched PubMed, Scopus, Science Citation Index and Social Sciences Citation Index, and Education Collection for systematic reviews with meta-analyses indexed from 2 November to 2 December 2020. A random sample of systematic reviews was initially drawn, and for reviews which considered randomised trials eligible for inclusion, which had not searched a trials register, we searched ClinicalTrials.gov, EudraCT, ANZCTR, and the WHO ICTRP search portal for eligible trials. We compared meta-analytic effect estimates before and after including results from additional trials identified. We found additional trials for 63% (63/101) of eligible reviews; however, trials with results that could contribute to a meta-analysis were identified for only 20% (20/101) of the reviews. On average, there was no difference in the meta-analytic effect estimates before versus after adding the new trials. In summary, searching clinical trial registers led to identification of additional trials for many reviews; however, very few trials had results available for inclusion in meta-analyses. Including results from the new trials led to no change in the meta-analytic estimates, on average. Trials registers would be even more valuable to systematic reviewers if more trialists made use of them (i.e., registered their trials and posted results in a timely manner).

Changing patterns in reporting and sharing of review data in systematic reviews with meta-analysis of the effects of interventions: cross sectional meta-research study

OBJECTIVES

To examine changes in completeness of reporting and frequency of sharing data, analytical code, and other review materials in systematic reviews over time; and factors associated with these changes.

DESIGN

Cross sectional meta-research study.

POPULATION

Random sample of 300 systematic reviews with meta-analysis of aggregate data on the effects of a health, social, behavioural, or educational intervention. Reviews were indexed in PubMed, Science Citation Index, Social Sciences Citation Index, Scopus, and Education Collection in November 2020.

MAIN OUTCOME MEASURES

The extent of complete reporting and the frequency of sharing review materials in the systematic reviews indexed in 2020 were compared with 110 systematic reviews indexed in February 2014. Associations between completeness of reporting and various factors (eg, self-reported use of reporting guidelines, journal policies on data sharing) were examined by calculating risk ratios and 95% confidence intervals.

RESULTS

Several items were reported suboptimally among 300 systematic reviews from 2020, such as a registration record for the review (n=113; 38%), a full search strategy for at least one database (n=214; 71%), methods used to assess risk of bias (n=185; 62%), methods used to prepare data for meta-analysis (n=101; 34%), and source of funding for the review (n=215; 72%). Only a few items not already reported at a high frequency in 2014 were reported more frequently in 2020. No evidence indicated that reviews using a reporting guideline were more completely reported than reviews not using a guideline. Reviews published in 2020 in journals that mandated either data sharing or inclusion of data availability statements were more likely to share their review materials (eg, data, code files) than reviews in journals without such mandates (16/87 (18%) v 4/213 (2%)).

CONCLUSION

Incomplete reporting of several recommended items for systematic reviews persists, even in reviews that claim to have followed a reporting guideline. Journal policies on data sharing might encourage sharing of review materials.

The transparency and reproducibility of systematic reviews in forensic science

Systematic reviews are indispensable tools for both reliably informing decision-makers about the state of the field and for identifying areas that need further study. Their value, however, depends on their transparency and reproducibility. Readers should be able to determine what was searched for and when, where the authors searched, and whether that search was predetermined or evolved based on what was found. In this article, we measured the transparency and reproducibility of systematic reviews in forensic science, a field where courts, policymakers, and legislators count on systematic reviews to make informed decisions. In a sample of 100 systematic reviews published between 2018 and 2021, we found that completeness of reporting varied markedly. For instance, 50 % of reviews claimed to follow a reporting guideline and such statements were only modestly related to compliance with that reporting guideline. As to specific reporting items, 82 % reported all of the databases searched, 22 % reported the review's full Boolean search logic, and just 7 % reported the review was registered. Among meta-analyses (n = 23), only one stated data was available and none stated the analytic code was available. After considering the results, we end with recommendations for improved regulation of reporting practices, especially among journals. Our results may serve as a useful benchmark as the field evolves.

Meta-research studies should improve and evaluate their own data sharing practices

Data sharing is gradually becoming a requirement across all fields of science, owing to its key benefits in verifying the reproducibility of findings and reusing existent data for new purposes. Although meta-research studies are complex, time-consuming and hinge on the availability of data produced and curated by others, there has been little focus on how they make their own data available. This is in stark contrast with the heightened attention data sharing has received in clinical research. Yet, as secondary data users par excellence, meta-researchers are ethically bound to both improving and evaluating data sharing practices, as well as correctly sharing their own data. We contrast particularities of data sharing in meta-research and clinical research, such as benefits, barriers, inadequate and potentially pervasive sharing practices. We conclude with an array of concrete and tailored recommendations for improvement.

Fear of COVID-19 and its association with mental health-related factors: systematic review and meta-analysis

BACKGROUND

The severity of COVID-19 remains high worldwide. Therefore, millions of individuals are likely to suffer from fear of COVID-19 and related mental health factors.

AIMS

The present systematic review and meta-analysis aimed to synthesize empirical evidence to understand fear of COVID-19 and its associations with mental health-related problems during this pandemic period.

METHOD

Relevant studies were searched for on five databases (Scopus, ProQuest, EMBASE, PubMed Central, and ISI Web of Knowledge), using relevant terms (COVID-19-related fear, anxiety, depression, mental health-related factors, mental well-being and sleep problems). All studies were included for analyses irrespective of their methodological quality, and the impact of quality on pooled effect size was examined by subgroup analysis.

RESULTS

The meta-analysis pooled data from 91 studies comprising 88 320 participants (mean age 38.88 years; 60.66% females) from 36 countries. The pooled estimated mean of fear of COVID-19 was 13.11 (out of 35), using the Fear of COVID-19 Scale. The associations between fear of COVID-19 and mental health-related factors were mostly moderate (Fisher's z = 0.56 for mental health-related factors; 0.54 for anxiety; 0.42 for stress; 0.40 for depression; 0.29 for sleep problems and -0.24 for mental well-being). Methodological quality did not affect these associations.

CONCLUSIONS

Fear of COVID-19 has associations with various mental health-related factors. Therefore, programmes for reducing fear of COVID-19 and improving mental health are needed.

Sonographic normal values for the cross-sectional area of the ulnar nerve: a systematic review and meta-analysis

PURPOSE

Nerve size is a commonly used sonographic parameter when assessing suspected entrapment of the ulnar nerve. We aimed to create a robust set of normal values, based on a critical review of published normal values.

METHODS

We performed a systematic evaluation of studies on normal ulnar nerve sizes, identified in PubMed, Embase, and Cochrane databases. Using meta-analyses, we determined pooled mean cross-sectional area (CSA) values for different anatomical locations of the ulnar nerve throughout the arm. Subgroup analyses were performed for gender, probe frequency, in- or exclusion of diabetic patients, position of the elbow and Asian versus other populations.

RESULTS

We identified 90 studies of which 77 studies were included for further analyses after quality review, resulting in data from 5772 arms of 3472 participants. Subgroup analyses show lower CSA values at at the wrist crease and proximal to the wrist crease when using low frequency probes (< 15 MHz) and at the wrist crease, proximal to the wrist crease, proximal forearm and the distal upper arm in Asians. CSA values were lower when in flexed position compared to extended position for the cubital tunnel inlet only. No difference was found for gender.

CONCLUSIONS

Our systematic review provides a comprehensive set of normal values at sites along the entire length of the ulnar nerve. This provides a foundation for clinical practise and upon which future studies could be more systematically compared.

TRIPS to Where? A Narrative Review of the Empirical Literature on Intellectual Property Licensing Models to Promote Global Diffusion of Essential Medicines

Governed through the World Trade Organization Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) since 1995, the current medical R&D system requires significant trade-offs between innovation and high monopoly prices for patented drugs that restrict patient access to medicines. Since its implementation, few amendments have been made to the original TRIPS agreement to allow low- and middle-income countries (LMICs) to facilitate access by generic manufacturers through flexible provisions, such as compulsory licensing and parallel import. Although a useful policy tool in theory, the routine use of TRIPS flexibilities in LMICs in the procurement of new essential medicines (EMs) is regarded as a 'last resort' due to strong political response in high-income countries (HICs) and new trade agreements' restrictions. In this context, access-oriented biomedical Public-Private Partnerships (PPPs) have emerged. More recently, leading multilateral health organizations have recommended different types of intellectual property (IP) interventions, voluntary biomedical patent pools, as strategies to reduce prices and increase the diffusion of novel EMs in LMICs. Nevertheless, the recent Ebola and COVID-19 outbreaks highlight growing concerns regarding the use of TRIPS flexibilities and the limited success of voluntary mechanisms in promoting access to medicines in the Global South amidst health crises. This review aims at describing the state-of-the-art empirical research on IP-related options and voluntary mechanisms applied by emerging PPPs to guarantee timely and affordable access to EM in LMICs and reflect on both models as access paradigms. Some suggestions are put forward for future research paths on the basis of these analyses and in response to contemporary debates on waiving key IP rights on COVID-19 therapies, diagnostics, and vaccines.