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Brain : a Journal of Neurology Feb 2024While Parkinson's disease remains clinically defined by cardinal motor symptoms resulting from nigrostriatal degeneration, it is now appreciated that the disease...
While Parkinson's disease remains clinically defined by cardinal motor symptoms resulting from nigrostriatal degeneration, it is now appreciated that the disease commonly consists of multiple pathologies, but it is unclear where these co-pathologies occur early in disease and whether they are responsible for the nigrostriatal degeneration. For the past number of years, we have been studying a well-characterized cohort of subjects with motor impairment that we have termed mild motor deficits. Motor deficits were determined on a modified and validated Unified Parkinson's Disease Rating Scale III but were insufficient in degree to diagnose Parkinson's disease. However, in our past studies, cases in this cohort had a selection bias, as both a clinical syndrome in between no motor deficits and Parkinson's disease, plus nigral Lewy pathology as defined post-mortem, were required for inclusion. Therefore, in the current study, we only based inclusion on the presence of a clinical phenotype with mild motor impairment insufficient to diagnose Parkinson's disease. Then, we divided this group further based upon whether or not subjects had a synucleinopathy in the nigrostriatal system. Here we demonstrate that loss of nigral dopaminergic neurons, loss of putamenal dopaminergic innervation and loss of the tyrosine hydroxylase-phenotype in the substantia nigra and putamen occur equally in mild motor deficit groups with and without nigral alpha-synuclein aggregates. Indeed, the common feature of these two groups is that both have similar degrees of AT8 positive phosphorylated tau, a pathology not seen in the nigrostriatal system of age-matched controls. These findings were confirmed with early (tau Ser208 phosphorylation) and late (tau Ser396/Ser404 phosphorylation) tau markers. This suggests that the initiation of nigrostriatal dopaminergic neurodegeneration occurs independently of alpha-synuclein aggregation and can be tau mediated.
Topics: Humans; Parkinson Disease; alpha-Synuclein; Parkinsonian Disorders; Synucleinopathies; Putamen; Substantia Nigra; Dopamine
PubMed: 38006313
DOI: 10.1093/brain/awad388 -
Journal of the Royal Statistical... Oct 2023Governments and public health authorities use seroprevalence studies to guide responses to the COVID-19 pandemic. Seroprevalence surveys estimate the proportion of...
Governments and public health authorities use seroprevalence studies to guide responses to the COVID-19 pandemic. Seroprevalence surveys estimate the proportion of individuals who have detectable SARS-CoV-2 antibodies. However, serologic assays are prone to misclassification error, and non-probability sampling may induce selection bias. In this paper, non-parametric and parametric seroprevalence estimators are considered that address both challenges by leveraging validation data and assuming equal probabilities of sample inclusion within covariate-defined strata. Both estimators are shown to be consistent and asymptotically normal, and consistent variance estimators are derived. Simulation studies are presented comparing the estimators over a range of scenarios. The methods are used to estimate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence in New York City, Belgium, and North Carolina.
PubMed: 38145241
DOI: 10.1093/jrsssa/qnad068 -
Environment International May 2024Some have looked forward to the publication of the results of the COSMOS study on brain tumors, because the potential biases from retrospective investigations...
Some have looked forward to the publication of the results of the COSMOS study on brain tumors, because the potential biases from retrospective investigations predominating the search for brain tumor risks of mobile phone use since the late 1990 s were deemed unresolvable by further investigations of that type. Indeed, prospective cohort studies typically have the advantage of being not or less affected by differential exposure misclassification, recall and selection bias, and, as they proceed in the direction of the time arrow, results are more easily interpreted in terms of causation. However, results of the COSMOS study published now in this journal are not of help for the risk assessment of mobile phone use and do not support the conclusions of the authors that their findings "suggest that the cumulative amount of mobile phone use is not associated with the risk of developing glioma, meningioma, or acoustic neuroma".
Topics: Brain Neoplasms; Humans; Cell Phone; Prospective Studies; Cohort Studies; Bias; Risk Assessment; Glioma; Meningioma; Neuroma, Acoustic; Radiation Exposure; Young Adult; Adult; Middle Aged; Aged
PubMed: 38677087
DOI: 10.1016/j.envint.2024.108665 -
Telemedicine Reports 2023Asynchronous telemedicine (ATM), which describes telemedical interaction between a patient and provider where neither party communicates simultaneously, is an important... (Review)
Review
BACKGROUND
Asynchronous telemedicine (ATM), which describes telemedical interaction between a patient and provider where neither party communicates simultaneously, is an important telemedicine modality that is seeing increased use. In this article, we summarize the published peer-reviewed literature specifically related to ATM to (1) identify terms or phrases that are used to describe ATM, (2) ascertain how this research has thus far addressed the various aspects of the quadruple aim of medicine, and (3) assess the methodological rigor of research on ATM. We also divided the literature into pre- and post-COVID-19 onset periods to identify potential variations in the literature between these two periods.
METHODS
This systematic literature review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The literature search, utilizing multiple databases and applying inclusion and exclusion criteria, initially produced 2624 abstracts for review. De-duplication and screening ultimately yielded 104 articles for data extraction.
RESULTS
"Store-and-forward" and variations of "e-visit" were the most frequently used alternative terms for ATM. Care quality was the most frequently addressed aspect of the Quadruple Aim of Medicine-more than double any other category-followed by patient satisfaction. We separated cost of care into two categories: patients' cost of care and providers' cost to provide care. Patient cost of care was the third most addressed aspect of the Quadruple Aim of Medicine followed by provider well-being and provider's cost to provide care. Methodological rigor of the studies was also addressed, with only 2 quantitative studies ranked "Strong," 5 ranked "Moderate," and 97 ranked "Weak." Qualitative studies were generally acceptable but struggled methodologically with accounting for all participants and articulation of results.
CONCLUSIONS
Although "store-and-forward" is somewhat more frequently used in the studies included in this review, variants of "e-visit," are growing in recent usage. Given the relative newness of modality, it is not surprising that quality of care is the most researched aspect of the Quadruple Aim of Medicine in ATM research. We anticipate more balance between these areas as research in this field matures. Primary areas of research need currently relate to practitioners-specifically their costs of providing care and well-being. Finally, future ATM research needs to address research challenges of selection bias and blinding in quantitative studies and improved participant tracking and articulation of both study design and results in qualitative studies.
PubMed: 38143795
DOI: 10.1089/tmr.2023.0052 -
Journal of the American Academy of... Oct 2023Data on the association between the development of autoimmune diseases and COVID-19 vaccination are limited.
BACKGROUND
Data on the association between the development of autoimmune diseases and COVID-19 vaccination are limited.
OBJECTIVE
To investigate the incidence and risk of autoimmune connective tissue disorders following mRNA-based COVID-19 vaccination.
METHODS
This nationwide population-based study was conducted in South Korea. Individuals who received vaccination between September 8, 2020-December 31, 2021, were identified. Historical prepandemic controls were matched for age and sex in 1:1 ratio. The incidence rate and risk of disease outcomes were compared.
RESULTS
A total of 3,838,120 vaccinated individuals and 3,834,804 controls without evidence of COVID-19 were included. The risk of alopecia areata, alopecia totalis, primary cicatricial alopecia, psoriasis, vitiligo, anti-neutrophil cytoplasmic antibody-associated vasculitis, sarcoidosis, Behcet disease, Crohn disease, ulcerative colitis, rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, Sjogren syndrome, ankylosing spondylitis, dermato/polymyositis, and bullous pemphigoid was not significantly higher in vaccinated individuals than in controls. The risk was comparable according to age, sex, type of mRNA-based vaccine, and cross-vaccination status.
LIMITATIONS
Possible selection bias and residual confounders.
CONCLUSION
These findings suggest that most autoimmune connective tissue disorders are not associated with a significant increase in risk. However, caution is necessary when interpreting results for rare outcomes due to limited statistical power.
Topics: Humans; COVID-19 Vaccines; COVID-19; Autoimmune Diseases; Connective Tissue Diseases; Alopecia Areata; Vaccination; Connective Tissue
PubMed: 37187424
DOI: 10.1016/j.jaad.2023.05.017 -
BMC Medical Research Methodology Aug 2023When conducting randomised controlled trials is impractical, an alternative is to carry out an observational study. However, making valid causal inferences from... (Review)
Review
BACKGROUND
When conducting randomised controlled trials is impractical, an alternative is to carry out an observational study. However, making valid causal inferences from observational data is challenging because of the risk of several statistical biases. In 2016 Hernán and Robins put forward the 'target trial framework' as a guide to best design and analyse observational studies whilst preventing the most common biases. This framework consists of (1) clearly defining a causal question about an intervention, (2) specifying the protocol of the hypothetical trial, and (3) explaining how the observational data will be used to emulate it.
METHODS
The aim of this scoping review was to identify and review all explicit attempts of trial emulation studies across all medical fields. Embase, Medline and Web of Science were searched for trial emulation studies published in English from database inception to February 25, 2021. The following information was extracted from studies that were deemed eligible for review: the subject area, the type of observational data that they leveraged, and the statistical methods they used to address the following biases: (A) confounding bias, (B) immortal time bias, and (C) selection bias.
RESULTS
The search resulted in 617 studies, 38 of which we deemed eligible for review. Of those 38 studies, most focused on cardiology, infectious diseases or oncology and the majority used electronic health records/electronic medical records data and cohort studies data. Different statistical methods were used to address confounding at baseline and selection bias, predominantly conditioning on the confounders (N = 18/49, 37%) and inverse probability of censoring weighting (N = 7/20, 35%) respectively. Different approaches were used to address immortal time bias, assigning individuals to treatment strategies at start of follow-up based on their data available at that specific time (N = 21, 55%), using the sequential trial emulations approach (N = 11, 29%) or the cloning approach (N = 6, 16%).
CONCLUSION
Different methods can be leveraged to address (A) confounding bias, (B) immortal time bias, and (C) selection bias. When working with observational data, and if possible, the 'target trial' framework should be used as it provides a structured conceptual approach to observational research.
Topics: Humans; Biomedical Research; Selection Bias; Databases, Factual; MEDLINE; Medical Oncology; Observational Studies as Topic
PubMed: 37587484
DOI: 10.1186/s12874-023-02000-9 -
Journal of Medical Internet Research Aug 2023Digital therapeutics (DTx), a class of software-based clinical interventions, are promising new technologies that can potentially prevent, manage, or treat a spectrum of... (Review)
Review
BACKGROUND
Digital therapeutics (DTx), a class of software-based clinical interventions, are promising new technologies that can potentially prevent, manage, or treat a spectrum of medical disorders and diseases as well as deliver unprecedented portability for patients and scalability for health care providers. Their adoption and implementation were accelerated by the need for remote care during the COVID-19 pandemic, and awareness about their utility has rapidly grown among providers, payers, and regulators. Despite this, relatively little is known about the capacity of DTx to provide economic value in care.
OBJECTIVE
This study aimed to systematically review and summarize the published evidence regarding the cost-effectiveness of clinical-grade mobile app-based DTx and explore the factors affecting such evaluations.
METHODS
A systematic review of economic evaluations of clinical-grade mobile app-based DTx was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 guidelines. Major electronic databases, including PubMed, Cochrane Library, and Web of Science, were searched for eligible studies published from inception to October 28, 2022. Two independent reviewers evaluated the eligibility of all the retrieved articles for inclusion in the review. Methodological quality and risk of bias were assessed for each included study.
RESULTS
A total of 18 studies were included in this review. Of the 18 studies, 7 (39%) were nonrandomized study-based economic evaluations, 6 (33%) were model-based evaluations, and 5 (28%) were randomized clinical trial-based evaluations. The DTx intervention subject to assessment was found to be cost-effective in 12 (67%) studies, cost saving in 5 (28%) studies, and cost-effective in 1 (6%) study in only 1 of the 3 countries where it was being deployed in the final study. Qualitative deficiencies in methodology and substantial potential for bias, including risks of performance bias and selection bias in participant recruitment, were identified in several included studies.
CONCLUSIONS
This systematic review supports the thesis that DTx interventions offer potential economic benefits. However, DTx economic analyses conducted to date exhibit important methodological shortcomings that must be addressed in future evaluations to reduce the uncertainty surrounding the widespread adoption of DTx interventions.
TRIAL REGISTRATION
PROSPERO International Prospective Register of Systematic Reviews CRD42022358616; https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022358616.
Topics: Humans; Cost-Benefit Analysis; COVID-19; Mobile Applications; Pandemics; Clinical Trials as Topic
PubMed: 37526973
DOI: 10.2196/47094 -
BMJ (Clinical Research Ed.) Jun 2023Mendelian randomisation (MR) studies, which investigate causal effects of exposures on disease, might be biased by sample selection and misclassification if phenotypes...
Mendelian randomisation (MR) studies, which investigate causal effects of exposures on disease, might be biased by sample selection and misclassification if phenotypes are not measured universally with the same definition in all study populations or participants. For example, in MR analyses of effects of exposures on covid-19, studies might include individuals with specific characteristics (eg, high socioeconomic position) meaning they are more likely to be tested for SARS-CoV-2 infection or respond to study questionnaires collecting data on infection and disease (selection bias). Alternatively, studies might assume those who were not tested have not been infected by SARS-CoV-2 or had covid-19 and are included as control participants (misclassification bias). In this article, a set of analyses to investigate the presence of selection or misclassification bias in MR studies is proposed and the implications of these on results is considered. The effect of body mass index on covid-19 susceptibility and severity is used as an illustrative example.
Topics: Humans; Body Mass Index; COVID-19; Risk Factors; Bias; Mendelian Randomization Analysis
PubMed: 37336561
DOI: 10.1136/bmj-2022-072148 -
Environmental Health Perspectives Aug 2023Neural tube defects (NTDs) affect pregnancies worldwide annually. Few nongenetic factors, other than folate deficiency, have been identified that may provide... (Review)
Review
BACKGROUND
Neural tube defects (NTDs) affect pregnancies worldwide annually. Few nongenetic factors, other than folate deficiency, have been identified that may provide intervenable solutions to reduce the burden of NTDs. Prenatal exposure to toxic metals [arsenic (As), cadmium (Cd), mercury (Hg), manganese (Mn) and lead (Pb)] may increase the risk of NTDs. Although a growing epidemiologic literature has examined associations, to our knowledge no systematic review has been conducted to date.
OBJECTIVE
Through adaptation of the Navigation Guide systematic review methodology, we aimed to answer the question "does exposure to As, Cd, Hg, Mn, or Pb during gestation increase the risk of NTDs?" and to assess challenges to evaluating this question given the current evidence.
METHODS
We selected available evidence on prenatal As, Cd, Hg, Mn, or Pb exposure and risk of specific NTDs (e.g., spina bifida, anencephaly) or all NTDs via a comprehensive search across MEDLINE, Embase, Web of Science, and TOXLINE databases and applied inclusion/exclusion criteria. We rated the quality and strength of the evidence for each metal. We applied a customized risk of bias protocol and evaluated the sufficiency of evidence of an effect of each metal on NTDs.
RESULTS
We identified 30 studies that met our criteria. Risk of bias for confounding and selection was high in most studies, but low for missing data. We determined that, although the evidence was limited, the literature supported an association between prenatal exposure to Hg or Mn and increased risk of NTDs. For the remaining metals, the evidence was inadequate to establish or rule out an effect.
CONCLUSION
The role of gestational As, Cd, or Pb exposure in the etiology of NTDs remains unclear and warrants further investigation in high-quality studies, with a particular focus on controlling confounding, mitigating selection bias, and improving exposure assessment. https://doi.org/10.1289/EHP11872.
Topics: Female; Pregnancy; Humans; Cadmium; Lead; Prenatal Exposure Delayed Effects; Neural Tube Defects; Mercury; Manganese; Arsenic
PubMed: 37647124
DOI: 10.1289/EHP11872