Pantelis Samartsidis
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View article: Impact of the first COVID-19 lockdown on HIV diagnosis in England: an observational time series study
Impact of the first COVID-19 lockdown on HIV diagnosis in England: an observational time series study Open
Background: Sexually transmitted infections (STIs) and Human Immunodeficiency Virus (HIV) prevention and care services in England were unavoidably disrupted by the Coronavirus Disease of 2019 (COVID-19) lockdowns, and it is likely incidenc…
View article: Evaluating the effect of direct-acting antiviral agent treatment scale-up on Hepatitis C virus prevalence among people who inject drugs in UK
Evaluating the effect of direct-acting antiviral agent treatment scale-up on Hepatitis C virus prevalence among people who inject drugs in UK Open
Real-world evidence showing substantial reductions in chronic HCV associated with increase of HCV treatment scale-up in the community thus supporting the effectiveness of HCV treatment as prevention in people who inject drugs.
View article: Examining changes in sexual lifestyles in Britain between 1990–2010: a latent class analysis approach
Examining changes in sexual lifestyles in Britain between 1990–2010: a latent class analysis approach Open
Background Understanding sexual lifestyles and how they change over time is important for determining the likelihood of sexual health outcomes. Standard descriptive and regression methods are limited in their ability to capture multidimens…
View article: A Bayesian multivariate factor analysis model for causal inference using time-series observational data on mixed outcomes
A Bayesian multivariate factor analysis model for causal inference using time-series observational data on mixed outcomes Open
Summary Assessing the impact of an intervention by using time-series observational data on multiple units and outcomes is a frequent problem in many fields of scientific research. Here, we propose a novel Bayesian multivariate factor analy…
View article: Evaluating the impact on health outcomes of an event that resulted in a delay in contact tracing of COVID-19 cases in England, September 2020: an observational study
Evaluating the impact on health outcomes of an event that resulted in a delay in contact tracing of COVID-19 cases in England, September 2020: an observational study Open
Objective In September 2020, 15 861 SARS-CoV-2 case records failed to upload from the Second Generation Surveillance System (SGSS) to the Contact Tracing Advisory Service (CTAS) tool, delaying the contact tracing of these cases. This study…
View article: Examining changes in sexual risk in Britain between 1990-2010: A Latent Class Analysis approach
Examining changes in sexual risk in Britain between 1990-2010: A Latent Class Analysis approach Open
Background : Understanding how sexual risk changes over time is important for determining the likelihood of adverse sexual health outcomes. There are different risk profiles in the population and standard descriptive or regression methods …
View article: distinct: A novel approach to differential distribution analyses
distinct: A novel approach to differential distribution analyses Open
We present distinct, a general method for differential analysis of full distributions that is well suited to applications on single-cell data, such as single-cell RNA sequencing and high-dimensional flow or mass cytometry data. High-throug…
View article: Nowcasting COVID-19 Deaths in England by Age and Region
Nowcasting COVID-19 Deaths in England by Age and Region Open
Understanding the trajectory of the daily number of COVID-19 deaths is essential to decisions on how to respond to the pandemic, but estimating this trajectory is complicated by the delay between deaths occurring and being reported. In Eng…
View article: Evaluating the impact on health outcomes of an event that resulted in a delay in contact tracing of COVID-19 cases
Evaluating the impact on health outcomes of an event that resulted in a delay in contact tracing of COVID-19 cases Open
Objective In September 2020, records of 15,861 SARS-CoV-2 cases failed to upload from the Second Generation Laboratory Surveillance System (SGSS) to the Contact Tracing Advisory Service (CTAS) tool, resulting in a delay in the contact trac…
View article: Evaluating the impact of local tracing partnerships on the performance of contact tracing for COVID-19 in England
Evaluating the impact of local tracing partnerships on the performance of contact tracing for COVID-19 in England Open
Assessing the impact of an intervention using time-series observational data on multiple units and outcomes is a frequent problem in many fields of scientific research. In this paper, we present a novel method to estimate intervention effe…
View article: Evaluating the impact of local tracing partnerships on the performance\n of contact tracing for COVID-19 in England
Evaluating the impact of local tracing partnerships on the performance\n of contact tracing for COVID-19 in England Open
Assessing the impact of an intervention using time-series observational data\non multiple units and outcomes is a frequent problem in many fields of\nscientific research. In this paper, we present a novel method to estimate\nintervention e…
View article: Modelling the impact of the tier system on SARS-CoV-2 transmission in the UK between the first and second national lockdowns
Modelling the impact of the tier system on SARS-CoV-2 transmission in the UK between the first and second national lockdowns Open
Objective To measure the effects of the tier system on the COVID-19 pandemic in the UK between the first and second national lockdowns, before the emergence of the B.1.1.7 variant of concern. Design This is a modelling study combining esti…
View article: Correction: Early life socioeconomic position and mortality from cardiovascular diseases: an application of causal mediation analysis in the Stockholm Public Health Cohort
Correction: Early life socioeconomic position and mortality from cardiovascular diseases: an application of causal mediation analysis in the Stockholm Public Health Cohort Open
View article: Impact of the Tier system on SARS-CoV-2 transmission in the UK between the first and second national lockdowns
Impact of the Tier system on SARS-CoV-2 transmission in the UK between the first and second national lockdowns Open
Objective Measure the effects of the Tier system on the COVID-19 pandemic in the UK between the first and second national lockdowns, before the emergence of the B.1.1.7 variant of concern. Design Modelling study combining estimates of the …
View article: Evaluating the power of the causal impact method in observational studies of HCV treatment as prevention
Evaluating the power of the causal impact method in observational studies of HCV treatment as prevention Open
Objectives The causal impact method (CIM) was recently introduced for evaluation of binary interventions using observational time-series data. The CIM is appealing for practical use as it can adjust for temporal trends and account for the …
View article: <i>distinct</i>: a novel approach to differential distribution analyses
<i>distinct</i>: a novel approach to differential distribution analyses Open
We present distinct , a general method for differential analysis of full distributions that is well suited to applications on single-cell data, such as single-cell RNA sequencing and high-dimensional flow or mass cytometry data. High-throu…
View article: Nowcasting CoVID-19 Deaths in England by Age and Region
Nowcasting CoVID-19 Deaths in England by Age and Region Open
Understanding the trajectory of the daily numbers of deaths in people with CoVID-19 is essential to decisions on the response to the CoVID-19 pandemic. Estimating this trajectory from data on numbers of deaths is complicated by the delay b…
View article: Estimating the prevalence of missing experiments in a neuroimaging meta‐analysis
Estimating the prevalence of missing experiments in a neuroimaging meta‐analysis Open
Coordinate‐based meta‐analyses (CBMA) allow researchers to combine the results from multiple functional magnetic resonance imaging experiments with the goal of obtaining results that are more likely to generalize. However, the interpretati…
View article: A Bayesian Multivariate Factor Analysis Model for Evaluating an Intervention by Using Observational Time Series Data on Multiple Outcomes
A Bayesian Multivariate Factor Analysis Model for Evaluating an Intervention by Using Observational Time Series Data on Multiple Outcomes Open
Summary A problem that is frequently encountered in many areas of scientific research is that of estimating the effect of a non-randomized binary intervention on an outcome of interest by using time series data on units that received the i…
View article: distinct: a novel approach to differential distribution analyses
distinct: a novel approach to differential distribution analyses Open
High-throughput single-cell data reveal an unprecedented view of cell identity and allow showing complex variations between conditions; nonetheless, most methods for differential expression target differences in the mean, and struggle to i…
View article: distinct: a method for differential analyses via hierarchical permutation tests, with applications to single-cell data
distinct: a method for differential analyses via hierarchical permutation tests, with applications to single-cell data Open
View article: Evaluating the population impact of hepatitis C direct acting antiviral treatment as prevention for people who inject drugs (EPIToPe) – a natural experiment (protocol)
Evaluating the population impact of hepatitis C direct acting antiviral treatment as prevention for people who inject drugs (EPIToPe) – a natural experiment (protocol) Open
Introduction Hepatitis C virus (HCV) is the second largest contributor to liver disease in the UK, with injecting drug use as the main risk factor among the estimated 200 000 people currently infected. Despite effective prevention interven…
View article: Review of methods for assessing the causal effect of binary interventions from aggregate time-series observational data
Review of methods for assessing the causal effect of binary interventions from aggregate time-series observational data Open
Researchers are often interested in assessing the impact of an intervention on an outcome of interest in situations where the intervention is non-randomised, information is available at an aggregate level, the intervention is only applied …
View article: Assessing the Causal Effect of Binary Interventions from Observational Panel Data with Few Treated Units
Assessing the Causal Effect of Binary Interventions from Observational Panel Data with Few Treated Units Open
Researchers are often challenged with assessing the impact of an intervention on an outcome of interest in situations where the intervention is nonrandomised, the intervention is only applied to one or few units, the intervention is binary…
View article: The Coordinate-Based Meta-Analysis of Neuroimaging Data
The Coordinate-Based Meta-Analysis of Neuroimaging Data Open
Neuroimaging meta-analysis is an area of growing interest in statistics. The special characteristics of neuroimaging data render classical meta-analysis methods inapplicable and therefore new methods have been developed. We review existing…
View article: Bayesian log-Gaussian Cox process regression with applications to fMRI meta-analysis
Bayesian log-Gaussian Cox process regression with applications to fMRI meta-analysis Open
A typical neuroimaging study will produce a 3D brain statistic image that summarises the evidence for activation during the experiment. However, for practical reasons those images are rarely published; instead, authors only report the (x,y…
View article: Neuroimaging Statistics Research at Warwick Presentations
Neuroimaging Statistics Research at Warwick Presentations Open
This collection contains slides from the Neuroimaging Statistics Research at Warwick seminars during the years 2014-2017.
View article: W Xue et al (2014): Identifying functional co-activation patterns in neuroimaging studies via Poisson graphical models
W Xue et al (2014): Identifying functional co-activation patterns in neuroimaging studies via Poisson graphical models Open
Talk given as part of Neuroimaging Statistics Research at Warwick seminars on 29th January 2015.
View article: K-J Lee et al (2014): Spatial Bayesian Variable Selection Models on Functional Magnetic Resonance Imaging Time-Series Data
K-J Lee et al (2014): Spatial Bayesian Variable Selection Models on Functional Magnetic Resonance Imaging Time-Series Data Open
Talk given as part of Neuroimaging Statistics Research at Warwick seminars on 16th October 2014.
View article: Point process modelling of coordinate-based meta-analysis neuroimaging data
Point process modelling of coordinate-based meta-analysis neuroimaging data Open
Now over 25 years old, functional magnetic resonance imaging (fMRI) has made significant contributions in improving our understanding of the human brain function. However, some limitations of fMRI studies, including those associated with t…