Publications by authors named "Linda Nab"

Background: The COVID-19 pandemic disrupted health-care delivery, including difficulty accessing in-person care, which could have increased the need for strong pharmacological pain relief. Due to the risks associated with overprescribing of opioids, especially to vulnerable populations, we aimed to quantify changes to measures during the COVID-19 pandemic, overall, and by key subgroups.

Methods: For this interrupted time-series analysis study conducted in England, with National Health Service England approval, we used routine clinical data from more than 20 million general practice adult patients in OpenSAFELY-TPP, which is a a secure software platform for analysis of electronic health records.

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Article Synopsis
  • Electronic health records (EHRs) are essential for researching medical products and informing public health, but reproducibility in EHR research is a significant challenge.
  • OpenSAFELY is an open-source software platform created during the COVID-19 pandemic to improve the reproducibility of research using EHRs by standardizing workflows and ensuring consistent computational environments.
  • The platform promotes transparency by enforcing code-sharing, providing an audit trail for data usage, and integrating tools that support reproducible research practices.
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Background: Patients with severe coronavirus disease 2019 (COVID-19) present with persisting hypercoagulability, hypofibrinolysis and prolonged clot initiation as measured with viscoelastic assays. The objective of this study was to investigate the trajectories of traditional assays of hemostasis, routine and tissue plasminogen activator (tPA) rotational thromboelastometry (ROTEM) in COVID-19 patients and to study their association with mortality.

Methods: Patients enrolled within the Maastricht Intensive Care COVID (MaastrICCht) cohort were included.

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Background: Timely evidence of the comparative effectiveness between COVID-19 therapies in real-world settings is needed to inform clinical care. This study aimed to compare the effectiveness of nirmatrelvir/ritonavir versus sotrovimab and molnupiravir in preventing severe COVID-19 outcomes in non-hospitalised high-risk COVID-19 adult patients during Omicron waves.

Methods: With the approval of NHS England, we conducted a real-world cohort study using the OpenSAFELY-TPP platform.

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Background: Due to limited inclusion of patients on kidney replacement therapy (KRT) in clinical trials, the effectiveness of coronavirus disease 2019 (COVID-19) therapies in this population remains unclear. We sought to address this by comparing the effectiveness of sotrovimab against molnupiravir, two commonly used treatments for non-hospitalised KRT patients with COVID-19 in the UK.

Methods: With the approval of National Health Service England, we used routine clinical data from 24 million patients in England within the OpenSAFELY-TPP platform linked to the UK Renal Registry (UKRR) to identify patients on KRT.

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Article Synopsis
  • The study investigated how different demographic and clinical groups experienced varying mortality risks related to COVID-19 across five pandemic waves in England, using data from the OpenSAFELY platform.
  • A total of nearly 19 million adults were analyzed across each wave, with significant trends showing a decrease in crude COVID-19-related death rates from the first wave to the fifth.
  • The highest standardized death rates were found among older adults and those with certain health conditions, such as advanced kidney disease or dementia, especially in the first wave of the pandemic.
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Article Synopsis
  • The study aimed to determine patient eligibility and describe the coverage of antiviral drugs and neutralising monoclonal antibodies (nMAB) as treatments for COVID-19 in community settings in England.
  • A retrospective analysis was conducted on data from 23.4 million people, focusing on outpatients with COVID-19 who were at high risk for severe outcomes between December 2021 and April 2022.
  • Out of 93,870 high-risk patients identified, only 19,040 (20%) received treatment, with variations in treatment rates based on factors like age, ethnic background, risk group, and NHS region.
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Objective: To characterise factors associated with COVID-19 vaccine uptake among people with kidney disease in England.

Design: Retrospective cohort study using the OpenSAFELY-TPP platform, performed with the approval of NHS England.

Setting: Individual-level routine clinical data from 24 million people across GPs in England using TPP software.

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Objective: To compare the effectiveness of sotrovimab (a neutralising monoclonal antibody) with molnupiravir (an antiviral) in preventing severe outcomes of covid-19 in adult patients infected with SARS-CoV-2 in the community and at high risk of severe outcomes from covid-19.

Design: Observational cohort study with the OpenSAFELY platform.

Setting: With the approval of NHS England, a real world cohort study was conducted with the OpenSAFELY-TPP platform (a secure, transparent, open source software platform for analysis of NHS electronic health records), and patient level electronic health record data were obtained from 24 million people registered with a general practice in England that uses TPP software.

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Background: Coagulation abnormalities and coagulopathy are recognized as consequences of severe acute respiratory syndrome coronavirus 2 infection and the resulting coronavirus disease 2019 (COVID-19). Specifically, venous thromboembolism (VTE) has been reported as a frequent complication. By May 27, 2021, at least 93 original studies and 25 meta-analyses investigating VTE incidence in patients with COVID-19 had been published, showing large heterogeneity in reported VTE incidence ranging from 0% to 85%.

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Objective: Sensitivity analysis for random measurement error can be applied in the absence of validation data by means of regression calibration and simulation-extrapolation. These have not been compared for this purpose.

Study Design And Setting: A simulation study was conducted comparing the performance of regression calibration and simulation-extrapolation for linear and logistic regression.

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Measurement error in a covariate or the outcome of regression models is common, but is often ignored, even though measurement error can lead to substantial bias in the estimated covariate-outcome association. While several texts on measurement error correction methods are available, these methods remain seldomly applied. To improve the use of measurement error correction methodology, we developed mecor, an R package that implements measurement error correction methods for regression models with a continuous outcome.

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Statistical correction for measurement error in epidemiologic studies is possible, provided that information about the measurement error model and its parameters are available. Such information is commonly obtained from a randomly sampled internal validation sample. It is however unknown whether randomly sampling the internal validation sample is the optimal sampling strategy.

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Objectives: Epidemiologic studies often suffer from incomplete data, measurement error (or misclassification), and confounding. Each of these can cause bias and imprecision in estimates of exposure-outcome relations. We describe and compare statistical approaches that aim to control all three sources of bias simultaneously.

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Observational data are increasingly used with the aim of estimating causal effects of treatments, through careful control for confounding. Marginal structural models estimated using inverse probability weighting (MSMs-IPW), like other methods to control for confounding, assume that confounding variables are measured without error. The average treatment effect in an MSM-IPW may however be biased when a confounding variable is error prone.

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Big data is characterised not only by the size of data files, but also by the diversity of data sources and continuity in data collection. Technological developments make it possible to store and analyse ever larger and more complex data files. Unlike more conventional research data, big data are often collected without explicit research questions in mind, and analytical techniques are used to find patterns in the data or to generate hypotheses.

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