Background: Linkage of administrative data sources provides an efficient means of collecting detailed data on how individuals interact with cross-sectoral services, society, and the environment. These data can be used to supplement conventional cohort studies, or to create population-level electronic cohorts generated solely from administrative data. However, errors occurring during linkage (false matches/missed matches) can lead to bias in results from linked data.Aim: This paper provides guidance on evaluating linkage quality in cohort studies.Methods: We provide an overview of methods for linkage, describe mechanisms by which linkage error can introduce bias, and draw on real-world examples to demonstrate methods for evaluating linkage quality.Results: Methods for evaluating linkage quality described in this paper provide guidance on (i) estimating linkage error rates, (ii) understanding the mechanisms by which linkage error might bias results, and (iii) information that should be shared between data providers, linkers and users, so that approaches to handling linkage error in analysis can be implemented.Conclusion: Linked administrative data can enhance conventional cohorts and offers the ability to answer questions that require large sample sizes or hard-to-reach populations. Care needs to be taken to evaluate linkage quality in order to provide robust results.
Thrombocytopaenia is common in critically ill patients and associated with poor clinical outcomes. Current guideline recommendations for prophylactic platelet transfusions, to prevent bleeding in critically ill patients with thrombocytopaenia, are based on observational data. Recent studies conducted in non-critically ill patients have demonstrated harm associated with platelet transfusions and have also called into question the efficacy of platelet transfusion. To date, there are no well-conducted randomised controlled trials (RCTs) evaluating platelet transfusion in critically ill patients. To inform the design of such an RCT, we sought to characterise current clinical practice across four commonly encountered scenarios in non-bleeding critically ill adult patients with thrombocytopaenia. An online survey link was sent to Clinical Directors and contacts of all adult general ICUs participating in the Intensive Care National Audit and Research Centre Case Mix Programme national clinical audit (n=200). The survey collected data regarding the respondents place of work, training grade and their current individual practice and possible limits of equipoise for prescribing prophylactic platelet transfusions across four scenarios: prophylaxis but with no procedure planned (NPP); ultrasound guided insertion of a right internal jugular central venous catheter (JVI); percutaneous tracheostomy (PT); and surgery with a low bleeding risk (SLBR). After excluding nine responses with missing data on all four of the main questions, responses were received from 99 staff, covering 78 ICUs (39.0% of 200 ICUs invited to participate). While nearly all respondents (98.0%) indicated a platelet transfusion threshold of 30 x 10^9/L or less for patients with no planned procedure, thresholds for planned procedures varied widely and centred at medians of 40 x 10^9/L for JVI (range: 10 to 70), 50 x 10^9/L for SLBR (range: 10 to 100) and 70 x 10^9/L for PT (range: 20 to greater than 100). Current platelet transfusion practice in UK ICUs prior to invasive procedures with relatively low bleeding risks is highly variable. Well-designed studies are needed to determine the optimal platelet transfusion thresholds in critical care.
Rationale: Examining trends in patient characteristics, processes of care and outcomes, across an epidemic, provides important opportunities for learning. Objectives: To report and explore changes in admission rates, patient characteristics, processes of care and outcomes for all patients with COVID-19 admitted to intensive care units (ICUs) in England, Wales and Northern Ireland. Methods: Population cohort of 10,287 patients with COVID-19 in the Case Mix Programme national clinical audit from 1 February to 2 July, 2020. Analyses were stratified by time period (pre-peak, peak, post-peak) and geographical region. Multivariable logistic regression was used to estimate differences in 28-day mortality, adjusting for patient characteristics over time. Main results: Admissions to ICU peaked simultaneously across regions on 1 April, with ongoing admissions peaking ten days later. Compared with pre- and post-peak periods, patients admitted during the peak were slightly younger but had greater respiratory and renal dysfunction. Use of invasive ventilation and renal replacement reduced over time. Twenty-eight-day mortality reduced from 43.5% (95% CI 41.6% to 45.5%) pre-peak to 34.3% (95% CI 32.3% to 36.2%) post-peak; a difference of −8.8% (95% CI: −5.2%, −12.3%) after adjusting for patient characteristics. London experienced the highest admission rate and had higher mortality during the peak period but a greater reduction in post-peak mortality. Conclusion: This study highlights changes in patient characteristics, processes of care and outcomes, during the UK COVID-19 epidemic. After adjusting for the changes in patient characteristics and first 24-hour physiology, there was substantial improvement in 28-day mortality over the course of the epidemic.
New-onset atrial fibrillation (NOAF) is common in patients on an intensive care unit (ICU). Evidence guiding treatments is limited, though recent reports suggest beta blocker (BB) therapy is associated with reduced mortality.
Objectives The creation and evaluation of a national record linkage between substance misuse treatment, and inpatient hospitalisation data in England. Design A deterministic record linkage using personal identifiers to link the National Drug Treatment Monitoring System (NDTMS) curated by Public Health England (PHE), and Hospital Episode Statistics (HES) Admitted Patient Care curated by National Health Service (NHS) Digital. Setting and participants Adults accessing substance misuse treatment in England between 1 April 2018 and 31 March 2019 (n=268 251) were linked to inpatient hospitalisation records available since 1 April 1997. Outcome measures Using a gold-standard subset, linked using NHS number, we report the overall linkage sensitivity and precision. Predictors for linkage error were identified, and inverse probability weighting was used to interrogate any potential impact on the analysis of length of hospital stay. Results 79.7% (n=213 814) people were linked to at least one HES record, with an estimated overall sensitivity of between 82.5% and 83.3%, and a precision of between 90.3% and 96.4%. Individuals were more likely to link if they were women, white and aged between 46 and 60. Linked individuals were more likely to have an average length of hospital stay ≥5 days if they were men, older, had no fixed residential address or had problematic opioid use. These associations did not change substantially after probability weighting, suggesting they were not affected by bias from linkage error. Conclusions Linkage between substance misuse treatment and hospitalisation records offers a powerful new tool to evaluate the impact of treatment on substance related harm in England. While linkage error can produce misleading results, linkage bias appears to have little effect on the association between substance misuse treatment and length of hospital admission. As subsequent analyses are conducted, potential biases associated with the linkage process should be considered in the interpretation of any findings.
In the UK, 10% of admissions to intensive care units receive continuous renal replacement therapy with regional citrate anticoagulation replacing systemic heparin anticoagulation over the last decade. Regional citrate anticoagulation is now used in > 50% of intensive care units, despite little evidence of safety or effectiveness.
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