The evolution of evidence hierarchies: what can Bradford Hill's 'guidelines for causation' contribute?

Perfect health not so perfect after all - a methodological study on patient-reported outcome measures in 2574 patients following percutaneous coronary intervention

BACKGROUND

Patient-reported outcome measures (PROMs) are crucial to capture patients' health and illness status. Selecting the most suitable PROM to measure self-reported health in a specific study population is essential. Shortcomings of much used generic instruments have been identified in certain populations, and more investigation is needed to clarify the extent to which the generic instruments capture the aspects of health that really matter to patients. Therefore, the aim of this study was to determine floor and ceiling effects of a generic health utility instrument (EQ-5D-5L) in an international multi-centre cohort of patients after percutaneous coronary intervention (PCI) and further explore those with perfect health scores by using a disease-specific instrument.

METHODS

The CONCARDPCI study was conducted at seven large referral PCI centres in Norway and Denmark between June 2017 and May 2020. In all, 2574 unique patients were available for this analysis. The generic EQ-5D-5L descriptive system and visual analogue scale, and the disease-specific Myocardial Infarction Dimensional Assessment Scale (MIDAS) comprising 35 items measuring seven areas of health status and daily life challenges were used to scrutinize the aims. Latent class analyses were conducted to identify classes with similar patterns of daily life challenges based on MIDAS item scores within the group of patients with best possible EQ-5D-5L score ('perfect scorers').

RESULTS

There was a large ceiling effect on the EQ-5D-5L score in patients with coronary artery disease (CAD) with 32% scoring the best possible EQ-5D-5L score, suggesting perfect health. Latent class analysis on the MIDAS revealed, however, four classes where 17-46% of the perfect scorers did perceive challenges in health, particularly related to symptoms of fatigue, and worries about risk factors and side effects of medication.

CONCLUSION

To obtain an accurate picture of patients' health status, these results emphasize that both generic and disease-specific patient-reported outcomes measures are needed to capture the distinct problems that patients with CAD experience after PCI. Caution should be made when using the EQ-5D-5L as the sole measure, particularly in priority settings, due to its potential ceiling effect and the fact that important aspects of patient health may be neglected.

TRIAL REGISTRATION

NCT03810612.

Cannabinoids for Acute Postoperative Pain Management: A Systematic Review and Meta-Analysis of Clinical Trials

BACKGROUND

Poor acute postoperative pain control, coupled with the use of intravenous medications with a limited and unsafety efficacy spectrum, has led to new therapeutic alternative explorations to reduce adverse events while increasing its analgesic efficacy. There cannabinoids have been proposed as a useful control agent in post-surgical pain. Nevertheless, to date, there is no solid evidence to evaluate them. The current article sought to determine cannabinoids' effectiveness and safety in the aforementioned context.

METHODS

A systematic review of controlled clinical trials evaluated the efficacy and safety of cannabinoids for the treatment of acute postoperative pain. The study was structured under the Cochrane recommendations. Primary outcomes included: pain intensity reduction, the number and doses of rescue analgesics and adverse events.

RESULTS

Of 62 articles found, only five were included. Four of them presented high inter-observer agreement and 60% were classified as having a low risk of bias. When evaluating the objectives of each article, a disparity was found in the investigative methods and terms implemented. Due to the heterogeneity of methods, it was not possible to carry out meta-analytic evaluations and only qualitative evaluations were feasible.

CONCLUSIONS

Despite finding contradictory evidence in relation to the analgesic cannabis effect in the postoperative context, methodological disparities found in the included articles and the impossibility of performing collective quantitative analyses were more significant. Before concluding with the well-known sentence: "further intervention studies are necessary", this report has identified limitations and has proposed recommendations for the planning and execution of future cannabis clinical trials, which will support new and necessary evidence for stronger meta-analytic reviews.

SIGNIFICANCE

The management of severe pain after surgery, and the use of intravenous drugs with limited and potentially unsafe effectiveness, has led to the exploration of new treatment options to minimize side effects while improving pain relief. Cannabinoids have been suggested as a potential solution for managing post-surgical pain, but there is currently insufficient evidence to assess their effectiveness. The purpose of this article was to evaluate the effectiveness and safety of cannabinoids in this context.

Confounders: A threat to the interpretation of research findings in endodontics

Confounding is a significant challenge in endodontic research, as it can blur the true effect and relationship between exposure and outcomes, potentially compromising the internal validity of research findings. Confounding variables can create apparent differences between study groups when no actual difference exists or fail to reveal true differences when they are present. Additionally, confounding can lead to either an underestimation or an overestimation of the effect of exposure on the outcome. This narrative review aims to (i) define confounder variables and explain how to identify them, (ii) elaborate methods for controlling confounders, and (iii) discuss how confounders can obscure any causal relationship. Confounding variables can be controlled through study design such as randomization, matching and restriction, or adjusted using statistical methods like stratification and multivariable models. However, inadequate control of confounding can result in residual confounding, which poses a significant threat to the interpretation of findings in endodontic research.

The impact of malocclusion on tooth loss over a 20-year period: Findings from the Population-Based Study of Health in Pomerania (SHIP)

OBJECTIVE

Research is lacking examining the effect of malocclusion on tooth loss. The aim of this study was to analyze the possible impact of moderate and severe malocclusions on tooth loss over the course of twenty years.

MATERIAL AND METHODS

Of 1269 subjects aged between 25 and 49 years with at least 20 teeth of the population-based Study of Health in Pomerania in Germany, malocclusions were initially assessed according to a German orthodontic index of treatment priority between 1997 and 2001. The available participants were re-examined every 5 years up to 2021. Tooth loss was analyzed in multilevel survival analyses including tooth, jaw and subject level. The models were adjusted for age, sex, marital status, school education and coexisting malocclusions in the same participant.

RESULTS

Among 623 (49 %) participants with orthodontic treatment priority, 201 showed more than one malocclusion feature. Missing, unreplaced teeth as equivalent for hypodontia, increased overjet of 3-6 mm or > 6 mm, deep bite of > 3 mm with gingival contact, and posterior cusp-to-cusp bite were risk factors for tooth loss. Open bite of 1-2 mm, deep bite of > 3 mm without gingival contact, bilateral crossbite, and incisal crowding with ≤1/2 width of lateral incisor were protective against tooth loss.

CONCLUSIONS

Given the negative and positive impacts of some malocclusions on tooth loss, other potential detrimental effects on oral health and psycho-social well-being were not considered in this study.

CLINICAL SIGNIFICANCE

This long-term study showed for the first time, that some malocclusions in adults can cause tooth loss and others are protective. This should be weighed in the decision making process for orthodontic treatment.

Occurrence and Time of Onset of Intraventricular Hemorrhage in Preterm Neonates: A Systematic Review and Meta-Analysis of Individual Patient Data

Importance

Intraventricular hemorrhage (IVH) has been described to typically occur during the early hours of life (HOL); however, the exact time of onset is still unknown.

Objective

To investigate the temporal distribution of IVH reported in very preterm neonates.

Data Sources

PubMed, Embase, Cochrane Library, and Web of Science were searched on May 9, 2024.

Study Selection

Articles were selected in which at least 2 cranial ultrasonographic examinations were performed in the first week of life to diagnose IVH. Studies with only outborn preterm neonates were excluded.

Data Extraction And Synthesis

Data were extracted independently by 3 reviewers. A random-effects model was applied. This study is reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. The Quality in Prognostic Studies 2 tool was used to assess the risk of bias.

Main Outcomes And Measures

The overall occurrence of any grade IVH and severe IVH among preterm infants was calculated along with a 95% CI. The temporal distribution of the onset of IVH was analyzed by pooling the time windows 0 to 6, 0 to 12, 0 to 24, 0 to 48, and 0 to 72 HOL. A subgroup analysis was conducted using studies published before and after 2007 to allow comparison with the results of a previous meta-analysis.

Results

A total of 21 567 records were identified, of which 64 studies and data from 9633 preterm infants were eligible. The overall rate of IVH did not decrease significantly before vs after 2007 (36%; 95% CI, 30%-42% vs 31%; 95% CI, 25%-36%), nor did severe IVH (10%; 95% CI, 7%-13% vs 11%; 95% CI, 8%-14%). The proportion of very early IVH (up to 6 HOL) after 2007 was 9% (95% CI, 3%-23%), which was 4 times lower than before 2007 (35%; 95% CI, 24%-48%). IVH up to 24 HOL before and after 2007 was 44% (95% CI, 31%-58%) and 25% (95% CI, 15%-39%) and up to 48 HOL was 82% (95% CI, 65%-92%) and 50% (95% CI, 34%-66%), respectively.

Conclusion And Relevance

This systematic review and meta-analysis found that the overall prevalence of IVH in preterm infants has not changed significantly since 2007, but studies after 2007 showed a later onset as compared with earlier studies, with only a small proportion of IVHs occurring before 6 HOL.

Use of Causal Framework to Evaluate Effect of Abuse Deterrent Properties of Extended-Release Oxycodone on Tampering in a Real-World Settings

PURPOSE

To assess whether exposure to an extended-release (ER) oxycodone with abuse deterrent properties (ADF) reduced tampering of oxycodone in a real-world, postmarket setting to address the thinking behind Category 4 labeling by the FDA.

METHODS

Data from an observational cross-sectional study of the general adult population (2022) was used under a causal framework to estimate the confounding-adjusted odds of tampering oxycodone after exposure to two types of ADF ER oxycodone. The tampering behaviors of those who used only single entity immediate-release (SE-IR) oxycodone was used as a comparison. The tampering outcome was defined as use by snorting, smoking, or injecting any oxycodone (ER or SE-IR). A directed acyclic graph was used to identify covariates. Average treatment effect among the treated was estimated using inverse propensity score weighting combined with survey weights in a regression.

RESULTS

In 2022, 0.14% and 3.0% among the general population reported using the two ER oxycodone groups, while 2.4% used SE-IR oxycodone. Propensity score analyses with both comparators (common support > 98%) balanced demographic, health, and drug use covariates. After adjustment for selection and confounding bias, among those who used ER oxycodone group 1 the odds ratio of tampering with any form of oxycodone was elevated but not statistically significant (2.25; 95% CI: 0.94, 5.39). The odds ratio of tampering by users of ER oxycodone group 2 was significantly elevated (1.90; 95% CI: 1.08, 3.19).

CONCLUSIONS

Tampering of ER oxycodone products by individuals was rare. We found evidence suggestive of elevated odds of tampering behaviors with use of an ADF ER oxycodone.

Conceptualizing problematic use of medicinal Cannabis: Development and preliminary validation of a brief screening questionnaire

The use of Medicinal Cannabis (MC) for treating chronic pain is increasing, globally, yet the definition of problematic MC use remains unclear. Defining problematic use of cannabis in medical and non-medical contexts may be fundamentally different since individuals prescribed MC often experience physical dependence, which do not necessarily imply pathology. We aimed to conceptualize problematic use of MC and develop a brief questionnaire for identifying and quantifying problematic MC use. Content validation used a broad definition of problematic substance use, adapting and compiling an initial list of 36 items from various sources: (a) screening tools for assessing problematic prescription opioid medication use; (b) screening tools for problematic recreational cannabis use and (c) qualitative interviews with MC patients. 390 American self-identified chronic pain patients holding a MC card rated each item from the initial list on a 5-point frequency scale and filled out questionnaires assessing various clinical outcomes. Following initial item titration, a multi-group measurement invariance comparison strategy, using two external indicators: alcohol-related problems and depression, resulted a final eight-item list that met fit quality in a baseline model, presented excellent internal consistency reliability (α = 0.929), and significantly correlated with anxiety and low quality of life. Items in the final list related predominantly to negative consequences of MC use. Problematic use of MC is characterized by negative physiological, social, emotional and functional consequences. The final eight-item list was named the Medicinal Cannabis Negative Consequences Scale (MCNCS), emerging as a brief measure for problematic MC use and demonstrating preliminary reliability and validity, which could aid clinicians and researchers.

A Causality Assessment Framework for COVID-19 Vaccines and Adverse Events at the COVID-19 Vaccine Safety Research Center

During the coronavirus disease 2019 (COVID-19) pandemic, conclusively evaluating possible associations between COVID-19 vaccines and potential adverse events was of critical importance. The National Academy of Medicine of Korea established the COVID-19 Vaccine Safety Research Center (CoVaSC) with support from the Korea Disease Control and Prevention Agency to investigate the scientific relationship between COVID-19 vaccines and suspected adverse events. Although determining whether the COVID-19 vaccine was responsible for any suspected adverse event necessitated a systematic approach, traditional causal inference theories, such as Hill's criteria, encountered certain limitations and criticisms. To facilitate a systematic and evidence-based evaluation, the United States Institute of Medicine, at the request of the Centers for Disease Control and Prevention, offered a detailed causality assessment framework in 2012, which was updated in the recent report by the National Academies of Sciences, Engineering, and Medicine (NASEM) in 2024. This framework, based on a weight-of-evidence approach, allows the independent evaluation of both epidemiological and mechanistic evidence, culminating in a comprehensive conclusion about causality. Epidemiological evidence derived from population studies is categorized into four levels-high, moderate, limited, or insufficient-while mechanistic evidence, primarily from biological and clinical studies in animals and individuals, is classified as strong, intermediate, weak, or lacking. The committee then synthesizes these two types of evidence to draw a conclusion about the causal relationship, which can be described as "convincingly supports" ("evidence established" in the 2024 NASEM report), "favors acceptance," "favors rejection," or "inadequate to accept or reject." The CoVaSC has established an independent committee to conduct causality assessments using the weight-of-evidence framework, specifically for evaluating the causality of adverse events associated with COVID-19 vaccines. The aim of this study is to provide an overview of the weight-of-evidence framework and to detail the considerations involved in its practical application in the CoVaSC.

Effect of methylphenidate on height in pediatric attention-deficit hyperactivity disorder patients: a systematic review and meta-analysis

Methylphenidate (MPH), a first-line treatment for attention-deficit hyperactivity disorder (ADHD) management, has been the focus of debate for decades regarding its effect on growth. The aim of this PRISMA meta-analysis was to determine the effect of MPH on height in children/adolescents with ADHD and its predictive factors based on literature reports. Available full-text articles were systematically reviewed to identify clinical studies of pediatric ADHD patients with height Z-score (HZS) data for monotherapy MPH-treated and non-treated groups. We estimated standardized mean differences (SMDs) of HZS or its changes from baseline (ΔHZS) between groups, then identified associated factors through subgroup analyses and meta-regression. For before-after treatment studies, the paired standard errors of ΔHZS were re-estimated to demonstrate in the forest plot. Risk of bias was analyzed using the Newcastle-Ottawa Scale. Among the 29 eligible studies, 26 reported ΔHZS with self-control groups, and ΔHZS or absolute HZS were compared to other external controls in 11 studies. A significant reduction was observed between post-MHP and pre-MPH use, with high heterogeneity (SMD =  - 0.40; 95% confidence interval = [ - 0.54,  - 0.27]; I2 = 91%). The study region, ADHD subtype, and stimulant-naïve status of patients at baseline may modify the effect on HZS. Because of the high clinical heterogeneity in observational studies, clinicians should consider the negative effect of MPH on height in ADHD patients by determining whether patients fulfill appropriate high-risk criteria. Further well-designed longitudinal studies are required to better quantify this effect, especially with prolonged treatment.

Is there evidence of a causal link between childhood maltreatment and attention deficit/hyperactivity disorder? A systematic review of prospective longitudinal studies using the Bradford-Hill criteria

Background

Studies report an elevated risk of maltreatment in children with attention deficit/hyperactivity disorder (ADHD), and elevated levels of ADHD in people who suffered childhood maltreatment (CM). However, the direction(s) of causality between CM and ADHD remain unclear-does ADHD create a context for CM, does CM cause ADHD, or both?

Objective

This study systematically reviews and qualitatively synthesizes the research evidence relating to this question using Bradford-Hill criteria for establishing causality-strength, temporality, dose-response and plausibility.

Methods

We conducted a systematic review, following PRISMA guidelines, of prospective longitudinal studies examining both CM and ADHD. We then used Bradford-Hill criteria to assess the quality of evidence for a causal link between CM and ADHD.

Results

All 11 included studies demonstrated an association between CM and ADHD. Seven included evidence for temporality: five suggesting that CM precedes ADHD in the lifespan; two suggesting ADHD precedes CM. Four studies demonstrated a dose response relationship in which greater CM exposure was associated with elevated risk of ADHD. Studies presented a range of plausible mechanisms, including CM causing ADHD through biological programming, versus ADHD causing CM through parental stress.

Conclusions

The high quality prospective longitudinal studies reviewed confirm the association between ADHD and CM, but present conflicting evidence about the direction of causality and mechanisms underpinning this association. To better understand the complex interplay between CM and ADHD, more studies using new research designs will be required that can partition effects by type of CM and account for bidirectional effects and other complexities.

Multiple chemical sensitivity scoping review protocol: overview of research and MCS construct

INTRODUCTION

Multiple chemical sensitivity (MCS) has been characterised by reported adverse responses to environmental exposures of common chemical agents (eg, perfumes, paint, cleaning products and other inhaled or ingested agents) in low doses considered non-toxic for the general population. There is currently no consensus on whether MCS can be established as a distinct disorder.

METHODS AND ANALYSIS

The scoping review of the literature will be guided by five questions: How is MCS defined and which diagnostic criteria have been proposed? What methods are used to report prevalence and incidence estimates of MCS? What are the characteristics of the body of scientific evidence that addresses whether MCS is a distinct disorder or syndrome? What underlying mechanisms for MCS have been proposed in the scientific literature? Which treatment and management approaches for MCS have been evaluated in empirical research studies? We will conduct a comprehensive search in 14 research databases. Citation screening will be supported by machine learning algorithms. Two independent reviewers will assess eligibility of full-text publications against prespecified criteria. Data abstraction will support concise evidence tables. A formal consultation exercise will elicit input regarding the review results and presentation. The existing research evidence will be documented in a user-friendly visualisation in the format of an evidence map.

ETHICS AND DISSEMINATION

Determined to be exempt from review (UP-22-00516). Results will be disseminated through a journal manuscript and data will be publicly accessible through an online data repository.

REGISTRATION DETAILS

The protocol is registered in Open Science Framework (osf.io/4a3wu).

Are predictions of bovine tuberculosis-infected herds unbiased and precise?

Bovine tuberculosis (bTB) is prevalent among livestock and wildlife in many countries including New Zealand (NZ), a country which aims to eradicate bTB by 2055. This study evaluates predictions related to the numbers of livestock herds with bTB in NZ from 2012 to 2021 inclusive using both statistical and mechanistic (causal) modelling. Additionally, this study made predictions for the numbers of infected herds between 2022 and 2059. This study introduces a new graphical method representing the causal criteria of strength of association, such as R2, and the consistency of predictions, such as mean squared error. Mechanistic modelling predictions were, on average, more frequently (3 of 4) unbiased than statistical modelling predictions (1 of 4). Additionally, power model predictions were, on average, more frequently (3 of 4) unbiased than exponential model predictions (1 of 4). The mechanistic power model, along with annual updating, had the highest R2 and the lowest mean squared error of predictions. It also exhibited the closest approximation to unbiased predictions. Notably, significantly biased predictions were all underestimates. Based on the mechanistic power model, the biological eradication of bTB from New Zealand is predicted to occur after 2055. Disease eradication planning will benefit from annual updating of future predictions.

Psychosis Caused by a Somatic Condition: How to Make the Diagnosis? A Systematic Literature Review

BACKGROUND

First episode of psychosis (FEP) is a clinical condition that usually occurs during adolescence or early adulthood and is often a sign of a future psychiatric disease. However, these symptoms are not specific, and psychosis can be caused by a physical disease in at least 5% of cases. Timely detection of these diseases, the first signs of which may appear in childhood, is of particular importance, as a curable treatment exists in most cases. However, there is no consensus in academic societies to offer recommendations for a comprehensive medical assessment to eliminate somatic causes.

METHODS

We conducted a systematic literature search using a two-fold research strategy to: (1) identify physical diseases that can be differentially diagnosed for psychosis; and (2) determine the paraclinical exams allowing us to exclude these pathologies.

RESULTS

We identified 85 articles describing the autoimmune, metabolic, neurologic, infectious, and genetic differential diagnoses of psychosis. Clinical presentations are described, and a complete list of laboratory and imaging features required to identify and confirm these diseases is provided.

CONCLUSION

This systematic review shows that most differential diagnoses of psychosis should be considered in the case of a FEP and could be identified by providing a systematic checkup with a laboratory test that includes ammonemia, antinuclear and anti-NMDA antibodies, and HIV testing; brain magnetic resonance imaging and lumbar puncture should be considered according to the clinical presentation. Genetic research could be of interest to patients presenting with physical or developmental symptoms associated with psychiatric manifestations.

The impact of obesity: a narrative review

Obesity is a disease with a major negative impact on human health. However, people with obesity may not perceive their weight to be a significant problem and less than half of patients with obesity are advised by their physicians to lose weight. The purpose of this review is to highlight the importance of managing overweight and obesity by discussing the adverse consequences and impact of obesity. In summary, obesity is strongly related to >50 medical conditions, with many of them having evidence from Mendelian randomisation studies to support causality. The clinical, social and economic burdens of obesity are considerable, with these burdens potentially impacting future generations as well. This review highlights the adverse health and economic consequences of obesity and the importance of an urgent and concerted effort towards the prevention and management of obesity to reduce the burden of obesity.

The Need for Biomarkers in the ALS-FTD Spectrum: A Clinical Point of View on the Role of Proteomics

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are severely debilitating and progressive neurodegenerative disorders. A distinctive pathological feature of several neurodegenerative diseases, including ALS and FTD, is the deposition of aberrant protein inclusions in neuronal cells, which leads to cellular dysfunction and neuronal damage and loss. Despite this, to date, the biological process behind developing these protein inclusions must be better clarified, making the development of disease-modifying treatment impossible until this is done. Proteomics is a powerful tool to characterize the expression, structure, functions, interactions, and modifications of proteins of tissue and biological fluid, including plasma, serum, and cerebrospinal fluid. This protein-profiling characterization aims to identify disease-specific protein alteration or specific pathology-based mechanisms which may be used as markers of these conditions. Our narrative review aims to highlight the need for biomarkers and the potential use of proteomics in clinical practice for ALS-FTD spectrum disorders, considering the emerging rationale in proteomics for new drug development. Certainly, new data will emerge in the near future in this regard and support clinicians in the development of personalized medicine.

An application of the stress-diathesis model: A review about the association between smoking tobacco, smoking cessation, and mental health

Background

Worldwide, approximately 24% of all adults smoke, but smoking is up to twice as prevalent in people with mental ill-health. There is growing evidence that smoking may be a causal risk factor in the development of mental illness, and that smoking cessation leads to improved mental health.

Methods

In this scholarly review we have: (1) used a modern adaptation of the Bradford-Hill criteria to bolster the argument that smoking could cause mental ill-health and that smoking cessation could reverse these effects, and (2) by considering psychological, biological, and environmental factors, we have structured the evidence to-date into a stress-diathesis model.

Results

Our model suggests that smoking is a psychobiological stressor, but that the magnitude of this effect is mediated and modulated by the individual's diathesis to develop mental ill-health and other vulnerability and protective factors. We explore biological mechanisms that underpin the model, such as tobacco induced damage to neurological systems and oxidative stress pathways. Furthermore, we discuss evidence indicating that it is likely that these systems repair after smoking cessation, leading to better mental health.

Conclusion

Based on a large body of literature including experimental, observational, and novel causal inference studies, there is consistent evidence showing that smoking can negatively affect the brain and mental health, and that smoking cessation could reverse the mental ill-health caused by smoking. Our model suggests that smoking prevention and treatment strategies have a role in preventing and treating mental illness as well as physical illness.

A framework for synthesizing intervention evidence from multiple sources into a single certainty of evidence rating: Methodological developments from a US National Academies of Sciences, Engineering, and Medicine Committee

Despite research investment and a growing body of diverse evidence there has been no comprehensive review and grading of evidence for public health emergency preparedness and response practices comparable to those in medicine and other public health fields. The National Academies of Sciences, Engineering, and Medicine convened an ad hoc committee to develop and use methods for grading and synthesizing diverse types of evidence to create a single certainty of intervention-related evidence to support recommendations for Public Health Emergency Preparedness and Response Research. A 13-step consensus building method was used. Experts were first canvassed in public meetings, and a comprehensive review of existing methods was undertaken. Although aspects of existing review methodologies and evidence grading systems were relevant, none adequately covered all requirements for this specific context. Starting with a desire to synthesize diverse sources of evidence not usually included in systematic reviews and using GRADE for assessing certainty and confidence in quantitative and qualitative evidence as the foundation, we developed a mixed-methods synthesis review and grading methodology that drew on (and in some cases adapted) those elements of existing frameworks and methods that were most applicable. Four topics were selected as test cases. The process was operationalized with a suite of method-specific reviews of diverse evidence types for each topic. Further consensus building was undertaken through stakeholder engagement and feedback The NASEM committee's GRADE adaption for mixed-methods reviews will further evolve over time and has yet to be endorsed by the GRADE working group.

Epistemology of the side effect: anecdote and evidence in the digital age

Through the history of rxisk.org, this article explores some of the Web’s effects on the production and circulation of pharmaceutical knowledge. RxISK is an independent website that solicits reports from patients in order to uncover drug-induced harms which clinical trials and national pharmacovigilance schemes fail to identify. The first part of the article locates the origins of the project in the nearly 15-year struggle to obtain recognition and redress for one particular side effect of selective serotonin reuptake inhibitor (SSRI) antidepressants—their ability to trigger violent or suicidal behavior. That struggle, I show, brought to light the ways in which modern evidence-making practices obscure the harms of pharmacological treatment. The second part, based on interviews with the site’s creators, examines how RxISK’s data collection practices seek to convert the Web from a site for the circulation of misinformation into a usable source of new knowledge about drugs. The project’s originality, I argue, lies in its effort to reframe the relation between anecdote and evidence so as to liberate the patient’s voice from the burden of representativeness. Within this reframed epistemology, the project is also freed from the imperative of large-scale data extraction that increasingly dominates the economy of digital health.

Clinical recommendations: The role of mechanisms in the GRADE framework

The Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework has become one of the most influential frameworks for assessing quality of research and developing clinical recommendations. The GRADE framework has been presented as an evolution in the Evidence-Based Medicine (EBM) movement. Both GRADE and EBM emphasize effect estimates derived from population-level clinical trials and, as a consequence, devalue the role of mechanisms as the basis for clinical decisions. Although mechanisms do not hold the epistemic privilege of rigorous clinical trials in EBM reasoning, this paper will argue that mechanisms appear to be important in the use and application of GRADE, as described in the literature. The seemingly necessary role of mechanisms in the development of clinical recommendations has, so far, received little attention and is not explicitly featured in the literature describing GRADE. The analysis of the GRADE framework presented in this paper reveals an apparent tension between EBM's willingness to downplay mechanisms and what seems their inevitable use in GRADE. In this paper, we take the position that if mechanistic reasoning is inevitable in the use of GRADE, then the instructional literature on the framework would benefit from more explicit discussion of how to consider and integrate mechanisms.

Association of Promoting Housing Affordability and Stability With Improved Health Outcomes: A Systematic Review

IMPORTANCE

Housing insecurity-that is, difficulty with housing affordability and stability-is prevalent and results in increased risk for both homelessness and poor health. However, whether interventions that prevent housing insecurity upstream of homelessness improve health remains uncertain.

OBJECTIVE

To review evidence characterizing associations of primary prevention strategies for housing insecurity with adult physical health, mental health, health-related behaviors, health care use, and health care access.

EVIDENCE REVIEW

Pairs of independent reviewers systematically searched PubMed, Web of Science, EconLit, and the Social Interventions Research and Evaluation Network for quantitative studies published from 2005 to 2021 that evaluated interventions intended to directly improve housing affordability and/or stability either by supporting at-risk households (targeted primary prevention) or by enhancing community-level housing supply and affordability in partnership with the health sector (structural primary prevention). Risk of bias was appraised using validated tools, and the evidence was synthesized using modified Grading of Recommendations Assessment, Development, and Evaluation criteria.

FINDINGS

A total of 26 articles describing 3 randomized trials and 20 observational studies (16 longitudinal designs and 4 cross-sectional quasi-waiting list control designs) were included. Existing interventions have focused primarily on mitigating housing insecurity for the most vulnerable individuals rather than preventing housing insecurity outright. Moderate-certainty evidence was found that eviction moratoriums were associated with reduced COVID-19 cases and deaths. Certainty of evidence was low or very low for health associations of other targeted primary prevention interventions, including emergency rent assistance, legal assistance with waiting list priority for public housing, long-term rent subsidies, and homeownership assistance. No studies evaluated health system-partnered structural primary prevention strategies.

CONCLUSIONS AND RELEVANCE

This systematic review found mixed and mostly low-certainty evidence that interventions that promote housing affordability and stability were associated with improved adult health outcomes. Existing interventions may need to be paired with other efforts to address the structural determinants of health. As health care systems and insurers respond to increasing opportunities to invest in housing as a determinant of health, further research is needed to clarify where along the housing insecurity pathway interventions should focus for the most effective and equitable health impact.

The right to choose to abort an abortion: should pro-choice advocates support abortion pill reversal?

Abortion pill reversal (APR) treatment aims to halt an initiated medical abortion, wherein a pregnant woman takes progesterone after having taken the first of the two consecutive abortion pills, typically because she has changed her mind and no longer wants to abort the pregnancy. It is a controversial intervention, generally supported by those identifying as pro-life and opposed by those identifying as pro-choice. This paper examines whether, in principle, those identifying with the pro-choice view should support APR. We firstly examine the commitments of the pro-choice stance. We then briefly outline the evidence supporting the APR. Following this, we discuss potential consequences of APR on women's mental health and its safety. We conclude that those espousing the pro-choice standpoint should be, in principle, committed to supporting the availability of APR, while recognising that data on its efficacy may be difficult to obtain.

Causal assessment in evidence synthesis: A methodological review of reviews

In fields (such as population health) where randomised trials are often lacking, systematic reviews (SRs) can harness diversity in study design, settings and populations to assess the evidence for a putative causal relationship. SRs may incorporate causal assessment approaches (CAAs), sometimes called 'causal reviews', but there is currently no consensus on how these should be conducted. We conducted a methodological review of self-identifying 'causal reviews' within the field of population health to establish: (1) which CAAs are used; (2) differences in how CAAs are implemented; (3) how methods were modified to incorporate causal assessment in SRs. Three databases were searched and two independent reviewers selected reviews for inclusion. Data were extracted using a standardised form and summarised using tabulation and narratively. Fifty-three reviews incorporated CAAs: 46/53 applied Bradford Hill (BH) viewpoints/criteria, with the remainder taking alternative approaches: Medical Research Council guidance on natural experiments (2/53, 3.8%); realist reviews (2/53, 3.8%); horizontal SRs (1/53, 1.9%); 'sign test' of causal mechanisms (1/53, 1.9%); and a causal cascade model (1/53, 1.9%). Though most SRs incorporated BH, there was variation in application and transparency. There was considerable overlap across the CAAs, with a trade-off between breadth (BH viewpoints considered a greater range of causal characteristics) and depth (many alternative CAAs focused on one viewpoint). Improved transparency in the implementation of CAA in SRs in needed to ensure their validity and allow robust assessments of causality within evidence synthesis.

Effect of interventions for non-emergent medical transportation: a systematic review and meta-analysis

INTRODUCTION

Transportation is an important social determinant of health. We conducted a systematic review of the associations on health and health care utilization of interventions aimed at reducing barriers to non-emergency transportation and non-medical transportation.

METHODS

We searched three databases and the gray literature through mid-January 2022. Included studies needed to assess an intervention targeted at non-emergency or non-medical transportation barriers, report missed (or kept) visits, health care utilization, costs, or health outcomes. Data extraction was performed in duplicate and included information about study design, results, and risk of bias. Primary outcomes were frequency of missed appointments, health care utilization, costs, and health outcomes. Synthesis was both narrative and meta-analytic using a random effects model.

RESULTS

Twelve studies met inclusion criteria, three randomized trials, one controlled trial, and eight observational studies. All included studies had some element of risk of bias. Populations studied usually had chronic or serious health conditions or were poor. Interventions included van rides, bus or taxi vouchers, ride-sharing services, and others. Meta-analysis of seven studies (three trials, four observational studies) yielded a pooled estimate of missed appointments = 0.63 (95% confidence interval [CI] 0.48, 0.83) favoring interventions. Evidence on cost, utilization, and health outcomes were too sparse to support conclusions. Evidence on the effect of non-medical transportation is limited to a single study.

CONCLUSIONS AND RELEVANCE

Interventions aimed at non-emergency transportation barriers to access health care are associated with fewer missed appointments; the association with costs, utilization or health outcomes is insufficiently studied to reach conclusions. This review was registered in PROSPERO as ID CRD42020201875.

Depressive symptoms, but not anxiety, predict subsequent diagnosis of Coronavirus disease 19: a national cohort study

AIMS

Several diseases are linked to increased risk of Coronavirus disease 19 (COVID-19). Our aim was to investigate whether depressive and anxiety symptoms predict subsequent risk of COVID-19, as has been shown for other respiratory infections.

METHODS

We based our analysis on UK Biobank participants providing prospective data to estimate temporal association between depressive and anxiety symptoms and COVID-19. We estimated whether the magnitude of these symptoms predicts subsequent diagnosis of COVID-19 in this sample. Further, we evaluated whether depressive and anxiety symptoms predicted (i) being tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and (ii) COVID-19 in those tested.

RESULTS

Based on data from N = 135 102 participants, depressive symptoms (odds ratio (OR) = 1.052; 95% confidence interval (CI) 1.017-1.086; absolute case risk: (moderately) severe depression: 493 per 100 000 v. minimal depression: 231 per 100 000) but not anxiety (OR = 1.009; 95% CI 0.97-1.047) predicted COVID-19. While depressive symptoms but not anxiety predicted (i) being tested for SARS-CoV-2 (OR = 1.039; 95% CI 1.029-1.05 and OR = 0.99; 95% CI 0.978-1.002), (ii) neither predicted COVID-19 in those tested (OR = 1.015; 95% CI 0.981-1.05 and OR = 1.021; 95% CI 0.981-1.061). Results remained stable after adjusting for sociodemographic characteristics, multimorbidity and behavioural factors.

CONCLUSIONS

Depressive symptoms were associated with a higher risk of COVID-19 diagnosis, irrespective of multimorbidities. Potential underlying mechanisms to be elucidated include risk behaviour, symptom perception, healthcare use, testing likelihood, viral exposure, immune function and disease progress. Our findings highlight the relevance of mental processes in the context of COVID-19.

Compression Garments for Recovery from Muscle Damage: Evidence and Implications of Dose Responses

ABSTRACT

The use of compression garments (CG) has been associated with improved recovery following exercise-induced muscle damage. The mechanisms responsible are not well established, and no consensus exists regarding the effects of compression pressure (i.e., the "dose"), which until recently was seldom reported. With the increasing prevalence of studies reporting directly measured pressures, the present review aims to consolidate current evidence on optimal pressures for recovery from exercise-induced muscle damage. In addition, recent findings suggesting that custom-fitted garments provide greater precision and experimental control are discussed. Finally, biochemical data from human trials are presented to support a theoretical mechanism by which CG enhance recovery, with recommendations for future research. The effects of compression on adaptation remain unexplored. More studies are required to investigate the relationship between compression pressure and the recovery of performance and physiological outcomes. Furthermore, improved mechanistic understanding may help elucidate the optimal conditions by which CG enhance recovery.

Sleep syncope: a prospective cohort study

PURPOSE

Sleep syncope is defined as a form of vasovagal syncope which interrupts sleep. Long term follow-up has not been reported.

METHODS

Between 1999 and 2013 we diagnosed vasovagal syncope in 1105 patients of whom 69 also had sleep syncope. We compared these 69 patients in the sleep syncope group to 118 patients with classical vasovagal syncope consecutively investigated between 1999 and 2003. We compared baseline demography, syncope history, tilt test results and follow-up findings.

RESULTS

At baseline, age and gender distribution (mean ± standard deviation) of the classical VVS and sleep synocope groups were similar: 46 ± 21 vs. 47 ± 15 years (p  = 0.53), and 55% versus 66% female (p  = 0.28), respectively. Abdominal discomfort and vagotonia were more frequent in sleep syncope patients: 80% versus 8% and 33% versus 2% (p  < 0.001). Childhood syncope and blood-needle phobia were also more frequent in sleep syncope patients: 58% versus 15% and 69% versus 19% (p  < 0.001). Positive tilt test results were similar for the two groups (93% [classical VVS] vs. 91%; p  = 0.56). Blood pressure, heart rate and stroke volume changed in a similar manner from baseline to syncope (p  = 0.32, 0.34 and 0.18, respectively). Mean duration of follow-up for the classical VVS and sleep syncope groups, as recorded in the electronic records, were 17 (3-21) and 15 (7-27) years, respectively. Rates of mortality and of permanent pacemaker insertion were similar in the two groups: 16.2% (classical VVS) versus 7.6% (p  = 0.09) and 3% (classical VVS) versus 3% (p  = 0.9). Incidence of sleep episodes decreased from 1.9 ± 3 to 0.1 ± 0.3 episodes per year (p  < 0.001).

CONCLUSION

Sleep syncope is a subtype of vasovagal syncope with characteristic symptoms. Despite the severity of the sleep episodes, the prognosis is very good. Very few patients require permanent pacing, and nearly all respond to education and reassurance.

Signals were broadly positive for months, but never definitive: the tocilizumab story

Background

Most treatment guidelines for coronavirus disease 2019 (COVID-19) currently recommend tocilizumab in combination with dexamethasone in critically ill patients who are exhibiting rapid respiratory decompensation.

Aims

To produce a critical review and summary of the pathway which led to the repurposing of tocilizumab for COVID-19 treatment, from in vitro observations to guidelines recommendations.

Sources

All studies evaluating the effectiveness of tocilizumab to treat COVID-19 disease published between July 2020 and July 2021.

Content

Two large and methodologically well conducted observational studies, the TESEO and the STOP COVID cohorts, showed a reduction in the risk of invasive mechanical ventilation or death in patients treated with tocilizumab as compared to standard of care in 2020. Concomitantly, and up to February 2021, a number of randomized trials (RCTs) with small sample sizes were showing discrepant results. These RCTs had a number of issues: small sample size, various designs and inclusion criteria, and different dosages of tocilizumab used. The confidence interval of the meta-analytic estimate for the RCT results was consistent with the hypothesis of no efficacy of tocilizumab. In our opinion, this was mainly because the meta-analysis included small and heterogeneous studies. These results led to a delay in the inclusion of tocilizumab in guidelines which occurred only in the summer of 2021.

Implications

Although observational studies are unable to control for unmeasured confounding, they can be put together quickly during a pandemic and promptly provide important information. The large sample size allows us to investigate effect measure modifiers and to better target interventions. It is key that the effect size is somewhat large (RR > 2), all sources of bias are properly accounted for, and the direct evidence is weighted against these factors. It appears to us that for tocilizumab, not having dismissed the results of carefully designed and analysed observational studies in 2020 could have prevented many deaths over those months.

SARS-CoV-2 and the role of airborne transmission: a systematic review

Background: Airborne transmission is the spread of an infectious agent caused by the dissemination of droplet nuclei (aerosols) that remain infectious when suspended in the air. We carried out a systematic review to identify, appraise and summarise the evidence from studies of the role of airborne transmission of SARS-CoV-2. Methods: We searched LitCovid, MedRxiv, Google Scholar and the WHO Covid-19 database from 1 February to 20 December 2020 and included studies on airborne transmission. Data were dual extracted and we assessed quality using a modified QUADAS 2 risk of bias tool. Results: We included 67 primary studies and 22 reviews on airborne SARS-CoV-2. Of the 67 primary studies, 53 (79%) reported data on RT-PCR from air samples, 12 (18%) report cycle threshold values and 18 (127%) copies per sample volume. All primary studies were observational and of low quality. The research often lacked standard methods, standard sampling sizes and reporting items. We found 36 descriptions of different air samplers deployed. Of the 42 studies conducted in-hospital that reported binary RT-PCR tests, 24 (57%) reported positive results for SARs-CoV-2 (142 positives out of 1,403 samples: average 10.1%, range 0% to 100%). There was no pattern between the type of hospital setting (ICU versus non-ICU) and RT-PCR positivity. Seventeen studies reported potential air transmission in the outdoors or in the community, of which seven performed RT-PCR sampling, and two studies reported weak positive RNA samples for 2 or more genes (5 of 125 samples positive: average 4.0%). Ten studies attempted viral culture with no serial passage. Conclusion:  SARS-CoV-2 RNA is detected intermittently in the air in various settings. Standardized guidelines for conducting and reporting research on airborne transmission are needed. The lack of recoverable viral culture samples of SARS-CoV-2 prevents firm conclusions from being drawn about airborne transmission.

Assessing causality in epidemiology: revisiting Bradford Hill to incorporate developments in causal thinking

The nine Bradford Hill (BH) viewpoints (sometimes referred to as criteria) are commonly used to assess causality within epidemiology. However, causal thinking has since developed, with three of the most prominent approaches implicitly or explicitly building on the potential outcomes framework: directed acyclic graphs (DAGs), sufficient-component cause models (SCC models, also referred to as 'causal pies') and the grading of recommendations, assessment, development and evaluation (GRADE) methodology. This paper explores how these approaches relate to BH's viewpoints and considers implications for improving causal assessment. We mapped the three approaches above against each BH viewpoint. We found overlap across the approaches and BH viewpoints, underscoring BH viewpoints' enduring importance. Mapping the approaches helped elucidate the theoretical underpinning of each viewpoint and articulate the conditions when the viewpoint would be relevant. Our comparisons identified commonality on four viewpoints: strength of association (including analysis of plausible confounding); temporality; plausibility (encoded by DAGs or SCC models to articulate mediation and interaction, respectively); and experiments (including implications of study design on exchangeability). Consistency may be more usefully operationalised by considering an effect size's transportability to a different population or unexplained inconsistency in effect sizes (statistical heterogeneity). Because specificity rarely occurs, falsification exposures or outcomes (i.e., negative controls) may be more useful. The presence of a dose-response relationship may be less than widely perceived as it can easily arise from confounding. We found limited utility for coherence and analogy. This study highlights a need for greater clarity on BH viewpoints to improve causal assessment.

Assessing causality in epidemiology: revisiting Bradford Hill to incorporate developments in causal thinking

The nine Bradford Hill (BH) viewpoints (sometimes referred to as criteria) are commonly used to assess causality within epidemiology. However, causal thinking has since developed, with three of the most prominent approaches implicitly or explicitly building on the potential outcomes framework: directed acyclic graphs (DAGs), sufficient-component cause models (SCC models, also referred to as 'causal pies') and the grading of recommendations, assessment, development and evaluation (GRADE) methodology. This paper explores how these approaches relate to BH's viewpoints and considers implications for improving causal assessment. We mapped the three approaches above against each BH viewpoint. We found overlap across the approaches and BH viewpoints, underscoring BH viewpoints' enduring importance. Mapping the approaches helped elucidate the theoretical underpinning of each viewpoint and articulate the conditions when the viewpoint would be relevant. Our comparisons identified commonality on four viewpoints: strength of association (including analysis of plausible confounding); temporality; plausibility (encoded by DAGs or SCC models to articulate mediation and interaction, respectively); and experiments (including implications of study design on exchangeability). Consistency may be more usefully operationalised by considering an effect size's transportability to a different population or unexplained inconsistency in effect sizes (statistical heterogeneity). Because specificity rarely occurs, falsification exposures or outcomes (i.e., negative controls) may be more useful. The presence of a dose-response relationship may be less than widely perceived as it can easily arise from confounding. We found limited utility for coherence and analogy. This study highlights a need for greater clarity on BH viewpoints to improve causal assessment.

Interventions to Address Food Insecurity Among Adults in Canada and the US: A Systematic Review and Meta-analysis

Importance

Inadequate access to food is a risk factor for poor health and the effectiveness of federal programs targeting food insecurity, such as the Supplemental Nutrition Assistance Program (SNAP), are well-documented. The associations between other types of interventions to provide adequate food access and food insecurity status, health outcomes, and health care utilization, however, are unclear.

Objective

To review evidence on the association between food insecurity interventions and food insecurity status, clinically-relevant health outcomes, and health care utilization among adults, excluding SNAP.

Data Sources

A systematic search for English-language literature was performed in PubMed Central and Cochrane Trials databases (inception to January 23, 2020), the Social Interventions Research and Evaluation Network database (December 10, 2019); and the gray literature using Google (February 1, 2021).

Study Selection

Studies of any design that assessed the association between food insecurity interventions for adult participants and food insecurity status, health outcomes, and health care utilization were screened for inclusion. Studies of interventions that described addressing participants' food needs or reporting food insecurity as an outcome were included. Interventions were categorized as home-delivered food, food offered at a secondary site, monetary assistance in the form of subsidies or income supplements, food desert interventions, and miscellaneous.

Data Extraction and Synthesis

Data extraction was performed independently by 3 reviewers. Study quality was assessed using the Cochrane Risk of Bias Tool, the ROBINS-I (Risk of Bias in Non-Randomized Studies of Interventions) tool, and a modified version of the National Institutes of Health's Quality Assessment Tool for Before-After Studies With No Control. The certainty of evidence was based on GRADE (Grading of Recommendations Assessment, Development, and Evaluation) criteria and supplemented with mechanistic and parallel evidence. For outcomes within intervention categories with at least 3 studies, random effects meta-analysis was performed.

Main Outcomes and Measures

Food insecurity (measured through surveys; eg, the 2-item Hunger Vital Sign), health outcomes (eg, hemoglobin A1c), and health care utilization (eg, hospitalizations, costs).

Results

A total of 39 studies comprising 170 605 participants were included (8 randomized clinical trials and 31 observational studies). Of these, 14 studies provided high-certainty evidence of an association between offering food and reduced food insecurity (pooled random effects; adjusted odds ratio, 0.53; 95% CI, 0.33-0.67). Ten studies provided moderate-certainty evidence of an association between offering monetary assistance and reduced food insecurity (pooled random effects; adjusted odds ratio, 0.64; 95% CI, 0.49-0.84). There were fewer studies of the associations between interventions and health outcomes or health care utilization, and the evidence in these areas was of low or very low certainty that any food insecurity interventions were associated with changes in either.

Conclusions and Relevance

This systematic review with meta-analysis found that providing food and monetary assistance was associated with improved food insecurity measures; however, whether it translated to better health outcomes or reduced health care utilization was unclear.

Topical NSAIDs for acute local pain relief: in vitro characterization of drug delivery profiles into and through human skin

OBJECTIVE

The efficacy of topical nonsteroidal anti-inflammatory drugs (NSAIDs) relates not only to the individual NSAID used but also to differences in formulation design. The aim of this study was to investigate the fundamental differences in ibuprofen and diclofenac drug delivery vehicles, specifically gels and plasters, compared to a recently launched 200 mg ibuprofen medicated plaster and characterize the resulting dermatologic-pharmacokinetic profiles into and through ex vivo human skin layers.

METHODS

In vitro skin permeation testing over 24 h and sacrificial timepoint penetration experiments (at 1, 4, 8, 12, and 24 h) were conducted using an automated flow-through diffusion cell system. The amount of drug delivered to the epidermis, dermis, and receptor solution (representing deeper tissue) was determined by liquid chromatography-tandem mass spectrometry. Skin protein binding of ibuprofen and diclofenac was investigated by spiking skin homogenate with increasing concentrations of each drug and determining the fraction unbound.

RESULTS

Differences were observed in the amount of drug recovered at sacrificial timepoints and rate at which drug was delivered to the target site between plaster and gel formulations of ibuprofen and diclofenac and between plaster formulations of the same drug (ibuprofen). While the amount of drug quantified at sacrificial timepoints did not necessarily determine in vivo flux rates, differences in drug distribution within the skin layers indicated where drug reservoirs were formed.

CONCLUSIONS

These findings highlight the importance of intelligent formulation design in determining NSAID delivery through skin layers. Further work is required to quantify drug delivery into deeper tissues and the resultant local anti-inflammatory effects.

Framework for the public health assessment of electronic cigarettes

BACKGROUND

Electronic cigarettes (e-cigarettes) are relatively new products with substantial public health impacts. Evidence on their effects is diverse and emerging rapidly, presenting challenges to high-quality policymaking and decision-making. This paper addresses these challenges by developing and presenting a framework for the public health assessment of e-cigarettes, using the Australian context as an example.

METHODS

Framework development involved stakeholder engagement, development of guiding principles, and consideration of existing relevant frameworks and the evidence requirements of current policy options, identified in published and grey literature.

RESULTS

Guiding principles include the need for the framework to: be evidence based; include consideration of the likely balance of benefits and risks of e-cigarettes, uncertainty and safety; support equity; support the ongoing application of evidence to high-quality policy and practice; and consider potential competing interests. The framework draws upon: health technology assessment; health impact assessment; environmental health risk assessment; healthcare recommendations evidence evaluation; consumer goods regulation; medicine and chemical scheduling; tobacco product evaluation; previous reviews and the precautionary principle. Final framework components are: (1) characterisation of products under consideration; (2) definition of populations of interest; (3) characterisation of tobacco smoking, control and impacts on health and well-being; (4) review of evidence on patterns of e-cigarette use; (5) review of evidence on e-cigarette use and health outcomes; (6) assessment of likely risks, benefits and safety; (7) identification and assessment of policy options to optimise health outcomes.

CONCLUSIONS

Structured and ongoing public health assessment of e-cigarette use is likely to support health through enhancing evidence-based decision-making.

An Abductive Inference Approach to Assess the Performance-Enhancing Effects of Drugs Included on the World Anti-Doping Agency Prohibited List

Some have questioned the evidence for performance-enhancing effects of several substances included on the World Anti-Doping Agency's Prohibited List due to the divergent or inconclusive findings in randomized controlled trials (RCTs). However, inductive statistical inference based on RCTs-only may result in biased conclusions because of the scarcity of studies, inter-study heterogeneity, too few outcome events, or insufficient power. An abductive inference approach, where the body of evidence is evaluated beyond considerations of statistical significance, may serve as a tool to assess the plausibility of performance-enhancing effects of substances by also considering observations and facts not solely obtained from RCTs. Herein, we explored the applicability of an abductive inference approach as a tool to assess the performance-enhancing effects of substances included on the Prohibited List. We applied an abductive inference approach to make inferences on debated issues pertaining to the ergogenic effects of recombinant human erythropoietin (rHuEPO), beta₂-agonists and anabolic androgenic steroids (AAS), and extended the approach to more controversial drug classes where RCTs are limited. We report that an abductive inference approach is a useful tool to assess the ergogenic effect of substances included on the Prohibited List-particularly for substances where inductive inference is inconclusive. Specifically, a systematic abductive inference approach can aid researchers in assessing the effects of doping substances, either by leading to suggestions of causal relationships or identifying the need for additional research.

The nosological classification of whiplash-associated disorder: a narrative review

Whiplash-associated disorder (WAD) is the most common complaint and purported cause of chronic disability associated with motor vehicle collisions in North America. However, its construct validity remains controversial. This narrative review of the literature summarises the evidence underlying the most commonly theorised biological and psychosocial mechanisms of WAD pathogenesis. While the face validity of WAD is good, empirical evidence supporting the various constructs suggesting a causal link between a trauma mechanism and the development of symptoms is poor. Because individual expectations of recovery are outcome-predictive, future research is necessary to develop a better understanding of how to enhance expectancies in order to help affected motorists gain a greater sense of control over their health and wellbeing.

SARS-CoV-2 and the role of airborne transmission: a systematic review

Background: Airborne transmission is the spread of an infectious agent caused by the dissemination of droplet nuclei (aerosols) that remain infectious when suspended in the air. We carried out a systematic review to identify, appraise and summarise the evidence from studies of the role of airborne transmission of SARS-CoV-2. Methods: We searched LitCovid, MedRxiv, Google Scholar and the WHO Covid-19 database from 1 February to 20 December 2020 and included studies on airborne transmission. Data were dual extracted and we assessed quality using a modified QUADAS 2 risk of bias tool. Results: We included 67 primary studies and 22 reviews on airborne SARS-CoV-2. Of the 67 primary studies, 53 (79%) reported data on RT-PCR air samples, 12 report cycle threshold values and 18 copies per sample volume. All primary studies were observational and of low quality. The research often lacked standard methods, standard sampling sizes and reporting items. We found 36 descriptions of different air samplers deployed. Of the 42 studies conducted in-hospital that reported binary RT-PCR tests, 24 (57%) reported positive results for SARs-CoV-2 (142 positives out of 1,403 samples: average 10.1%, range 0% to 100%). There was no pattern between the type of hospital setting (ICU versus non-ICU) and RT-PCR positivity. Seventeen studies reported potential air transmission in the outdoors or in the community. Seven performed RT-PCR sampling, of which two studies report weak positive RNA samples for 2 or more genes (5 of 125 samples positive: average 4.0%). Ten studies attempted viral culture with no serial passage for viral culture. Conclusion:  SARS-CoV-2 RNA is detected intermittently in the air in various settings. Standardized guidelines for conducting and reporting research on airborne transmission are needed. The lack of recoverable viral culture samples of SARS-CoV-2 prevents firm conclusions over airborne transmission.

Is Loneliness a Cause or Consequence of Dementia? A Public Health Analysis of the Literature

Loneliness has been reframed from a 'social problem of old age' into a major public health problem. This transformation has been generated by findings from observational studies of a relationship between loneliness and a range of negative health outcomes including dementia. From a public health perspective, key to evaluating the relationship between loneliness and dementia is examining how studies define and measure loneliness, the exposure variable, and dementia the outcome. If we are not consistently measuring these then building a body of evidence for the negative health outcomes of loneliness is problematic. Three key criteria had to meet for studies to be included in our analysis. To test the proposition that loneliness is a cause of dementia we only included longitudinal studies. For inclusion studies had to measure loneliness at baseline, have samples free of dementia and assess dementia at follow up (specified as a minimum of 12 months). We identified 11 papers published between 2000 and 2018 that meet these criteria. These studies included seven different countries and only one was specifically focused upon dementia: all other studies were cohort studies focused upon ageing and health and wellbeing. There was extensive heterogeneity in how studies measured loneliness and dementia and in the use of co-variates. Loneliness was measured by either self-rating scales (n = 8) or scales (n = 3). Dementia was assessed by clinical tests (n = 5), diagnostic/screening tools (n = 3), cognitive function tests (n = 1), and self-reported doctor diagnosis (n = 2). Substantial variation in loneliness prevalence (range 5-20%) and dementia incidence (5-30 per 1000 person years at risk). Six studies did not report a statistically significant relationship between loneliness and dementia. Significant excess risk of dementia among those who were lonely ranged from 15% to 64%. None of these studies are directly comparable as four different loneliness and dementia measures were used. We suggest that the evidence to support a relationship between loneliness and dementia is inconclusive largely because of methodological limitations of existing studies. If we wish to develop this evidence base, then using a consistent set of loneliness and dementia outcome measures in major longitudinal studies would be of benefit.

Techniques for blood loss estimation in major non-cardiac surgery: a systematic review and meta-analysis

PURPOSE

Estimated blood loss (EBL) is an important tool in clinical decision-making and surgical outcomes research. It guides perioperative transfusion practice and serves as a key predictor of short-term perioperative risks and long-term oncologic outcomes. Despite its widespread clinical and research use, there is no gold standard for blood loss estimation. We sought to systematically review and compare techniques for intraoperative blood loss estimation in major non-cardiac surgery with the objective of informing clinical estimation and research standards.

SOURCE

A structured search strategy was applied to Ovid Medline, Embase, and Cochrane Library databases from inception to March 2020, to identify studies comparing methods of intraoperative blood loss in adult patients undergoing major non-cardiac surgery. We summarized agreement between groups of pairwise comparisons as visual estimation vs formula estimation, visual estimation vs other, and formula estimation vs other. For each of these comparisons, we described tendencies for higher or lower EBL values, consistency of findings, pooled mean differences, standard deviations, and confidence intervals.

PRINCIPLE FINDINGS

We included 26 studies involving 3,297 patients in this review. We found that visual estimation is the most frequently studied technique. In addition, visual techniques tended to provide lower EBL values than formula-based estimation or other techniques, though this effect was not statistically significant in pooled analyses likely due to sample size limitations. When accounting for the contextual mean blood loss, similar case-to-case variation exists for all estimation techniques.

CONCLUSIONS

We found that significant case-by-case variation exists for all methods of blood loss evaluation and that there is significant disagreement between techniques. Given the importance placed on EBL, particularly for perioperative prognostication models, clinicians should consider the universal adoption of a practical and reproducible method for blood loss evaluation.

TRIAL REGISTRATION

PROSPERO (CRD42015029439); registered: 18 November 2015.PROSPERO (CRD42015029439); registered: 18 November 2015.

Investigating the causal relationship between maltreatment and cognition in children: A systematic review

BACKGROUND

Cognitive impairment (i.e. lower IQ/cognitive development) in individuals who have experienced childhood maltreatment is well documented in the literature. It is not yet clear whether maltreatment itself causes cognitive impairment, or whether reduced cognitive functioning pre-dates maltreatment exposure and places children at risk of maltreatment.

OBJECTIVE

This systematic review critically evaluated the evidence for a causal association between child maltreatment and impaired cognition in children under 12 years.

METHODS

Following PRISMA guidelines, databases were searched and articles extracted according to inclusion criteria. Quality rating of articles was conducted independently by two reviewers and the evidence for a causal association was evaluated using guidelines based on the Hill criteria for causation in epidemiological and public health research.

RESULTS

31 articles were included in the review, with results that suggested lower IQ/cognitive development in maltreated children compared to controls, and a dose-response relationship between timing and duration of maltreatment and impaired cognition. Assessment of causality indicated strong evidence for a causal association between maltreatment and reduced overall cognitive performance in institutionalised children. Findings were less robust for non-institutionalised samples. Evidence regarding specific cognitive functions was mixed.

CONCLUSIONS

Extreme maltreatment may lead to reduced cognitive functioning in children under 12 years. More research is required to determine the impact of the nature and timing of maltreatment, as well as additional heritable and social factors, on specific profiles of cognition in this population.

Clinical Effectiveness and Resource Utilization of Surgery versus Endovascular Therapy for Chronic Limb-Threatening Ischemia

BACKGROUND

The clinical effectiveness of surgical versus endovascular therapy for chronic limb-threatening ischemia (CLTI) continues to be debated, and the resources required for each therapy are unclear.

METHODS

Systematic review of randomized controlled trials (RCTs) and observational studies comparing surgery with endovascular therapy for CLTI, which reported clinical effectiveness and resource utilization. Short-term and long-term clinical outcomes were examined.

RESULTS

The search yielded 4,231 titles, of which 17 publications met our inclusion criteria. Five publications were all from 1 RCT, and 12 publications were observational studies. In the RCT, the surgical approach had greater resource use in the first year (total hospital days across all admissions for surgery versus angioplasty: 46.14 ± 53.87 vs. 36.35 ± 51.39; P < 0.001; also true for days in high-dependency and intensive therapy units), but differences were not statistically significant in subsequent years. All-cause mortality presented a nonsignificant difference favoring angioplasty in the first 2 years (adjusted hazard ratio [aHR], 1.27; 95% confidence interval [95% CI], 0.75-2.15), but after 2 years, it favored surgical treatment (aHR, 0.34; 95% CI, 0.17-0.71). The observational studies reported short-term effectiveness and resource utilization favoring endovascular therapy, but most differences were not statistically significant. Long-term outcomes were more mixed; in particular, mortality outcomes generally favored surgery, although concluding that cause and effect is not possible as endovascularly treated patients tended to be older and may have had a shorter life expectancy regardless of therapy.

CONCLUSIONS

The clinical effectiveness and resource utilization of surgery compared with endovascular therapy for CLTI is not known with certainty and will not be known until ongoing trials report results. It is likely that findings will vary by the time horizon, where initial outcomes and utilization tend to favor endovascular interventions, but long-term outcomes favor surgical revascularization.

Manipulative evidence and medical interventions: some qualifications

The notion of causal evidence in medicine has been the subject of wide philosophical debate in recent years. The notion of evidence has been discussed mostly in connection with Evidence Based Medicine and, more in general, with the assessment of causal nexus in medical, and especially research contexts. "Manipulative evidence" is one of the notions of causal evidence that has stimulated much debate. It has been defined in slightly different ways, attributed different relevance, and recently placed at the core of Gillies' "action-related theory of causality", a view specifically meant to address causation in medicine. While in general sympathetic to Gillies' account, and totally convinced of the relevance of manipulative evidence and different sorts of interventions in the biomedical sciences, we believe that some further qualifications are needed to allow the notion of manipulative evidence to better express features of medical practice. In particular, we provide some qualification of the role of "interventional evidence" proposed by Gillies, suggesting a distinction between "interventional evidence" and "evidence for interventions". A case study from research on rare diseases is analyzed in depth and a multifaceted notion of manipulative evidence put forward that allows better understanding of what manipulations in medical contexts amount to and what their targets are.