Developing a research ready population-scale linked data ethnicity-spine in Wales (preprint)

Introduction: Ethnicity information is recorded routinely in electronic health records (EHRs); however, to date, there is no national standard or framework for harmonisation of the existing records. Methods and analysis The national ethnicity-spine uses anonymised individual-level population-scale ethnicity data from 26 EHR available through the Secure Anonymised Information Linkage (SAIL) Databank. A total of 46 million ethnicity records for 4,297,694 individuals in Wales-UK over 22 years (between 2000 and 2021) have been compiled in a harmonised, deduplicated longitudinal research ready data asset. We serialised this data and compared distribution of records over time for four selection approaches (Latest, Mode, Weighted-Mode and Composite) across age bands, sex, deprivation quintiles, health board, and residential location, against the ONS census 2011. The distribution of the dominant group (White) is minimally affected based on the four different selection approaches. Across all other ethnicity categorisations, the Mixed group was most susceptible to variation in distribution depending on the selection approach used and varied from a 0.6% prevalence across the Latest and Mode approach to a 1.1% prevalence for the Weighted-Mode, compared to the 3.1% prevalence for the Composite approach. Substantial alignment was observed with ONS census with the Latest group method (kappa= 0.68, 95% CI [0.67,0.71]) across all sub-groups. Conclusion We provides a reproducible EHR based resource enabling the investigation and evaluation of health inequalities related to ethnic groups in Wales. This generalisable method informs opportunities for the transferability of this methodology across the UK to platforms with comparable routine data sources. Ethics and dissemination This work was supported by the Con-COV team funded by Medical Research Council, Health Data Research UK, ADR Wales funded by ADR UK through the Economic and Social Research Council, and the Wales COVID-19 Evidence Centre, funded by Health and Care Research Wales.

Pre-COVID-19 pandemic health-related behaviours in children (2018-2020) and association with being tested for SARS-CoV-2 and testing positive for SARS-CoV-2 (2020-2021): a retrospective cohort study using survey data linked with routine health data in Wales, UK (preprint)

ABSTRACT Objectives Examine if pre-COVID-19 pandemic (prior March 2020) health-related behaviours during primary school are associated with i) being tested for SARS-CoV-2 and ii) testing positive between 1 March 2020 to 31 August 2021. Design Retrospective cohort study using an online cohort survey (January 2018 to February 2020) linked to routine PCR SARS-CoV-2 test results. Setting Children attending primary schools in Wales (2018-2020), UK who were part of the HAPPEN school network. Participants Complete linked records of eligible participants were obtained for n=7,062 individuals. 39.1% (n=2,764) were tested (age 10.6±0.9, 48.9% girls) and 8.1% (n=569) tested positive for SARS-CoV-2 (age 10.6±1.0, 54.5% girls). Main outcome measures Logistic regression of health-related behaviours and demographics were used to determine Odds Ratios (OR) of factors associated with i) being tested for SARS-CoV-2 and ii) testing positive for SARS-CoV-2. Results Consuming sugary snacks (1-2 days/week OR=1.24, 95% CI 1.04 – 1.49; 5-6 days/week 1.31, 1.07 – 1.61; reference 0 days) can swim 25m (1.21, 1.06 – 1.39) and age (1.25, 1.16 – 1.35) were associated with an increased likelihood of being tested for SARS-CoV-2. Eating breakfast (1.52, 1.01 – 2.27), weekly physical activity ≥ 60 mins (1-2 days 1.69, 1.04 – 2.74; 3-4 days 1.76, 1.10 – 2.82, reference 0 days), out of school club participation (1.06, 1.02 – 1.10), can ride a bike (1.39, 1.00 – 1.93), age (1.16, 1.05 – 1.28) and girls (1.21, 1.00 – 1.46) were associated with an increased likelihood of testing positive for SARS-CoV-2. Living in least deprived quintiles 4 (0.64, 0.46 – 0.90) and 5 (0.64, 0.46 – 0.89) compared to the most deprived quintile was associated with a decreased likelihood. Conclusions Associations may be related to parental health literacy and monitoring behaviours. Physically active behaviours may include co-participation with others, and exposure to SARS-CoV-2. A risk versus benefit approach must be considered given the importance of health-related behaviours for development. STRENGTHS AND LIMITATIONS Investigation of the association of pre-pandemic child health-related behaviour measures with subsequent SARS-CoV-2 testing and infection. Reporting of multiple child health behaviours linked at an individual-level to routine records of SARS-CoV-2 testing data through the SAIL Databank. Child-reported health behaviours were measured before the COVID-19 pandemic (1 January 2018 to 28 February 2020) which may not reflect behaviours during COVID-19. Health behaviours captured through the national-scale HAPPEN survey represent children attending schools that engaged with the HAPPEN Wales primary school network and may not be representative of the whole population of Wales. The period of study for PCR-testing for and testing positive for SARS-CoV-2 includes a time frame with varying prevalence rates, approaches to testing children (targeted and mass testing) and restrictions which were not measured in this study.

COVID-19 mitigation measures in primary schools and association with infection and school staff wellbeing: an observational survey linked with routine data in Wales, UK (preprint)

IntroductionSchool-based COVID-19 mitigation strategies have greatly impacted the primary school day (children aged 3-11) including: wearing face coverings, 2-metre distancing, no mixing of children, and no breakfast clubs or extra-curricular activities. This study examines these mitigation methods and association with COVID-19 infection, respiratory infection, and school staff wellbeing between October to December 2020 in Wales, UK. MethodsA school staff survey captured self-reported COVID-19 mitigation measures in the school, participant anxiety and depression, and open-text responses regarding experiences of teaching and implementing measures. These survey responses were linked to national-scale COVID-19 test results data to examine association of measures in the school and the likelihood of a positive (staff or pupil) COVID-19 case in the school (clustered by school, adjusted for school size and free school meals using logistic regression). Linkage was conducted through the SAIL (Secure Anonymised Information Linkage) Databank. ResultsResponses were obtained from 353 participants from 59 primary schools within 15 of 22 local authorities. Having more direct non-household contacts was associated with a higher likelihood of COVID-19 positive case in the school (1-5 contacts compared to none, OR 2.89 (1.01, 8.31)) and a trend to more self-reported cold symptoms. Staff face covering was not associated with a lower odds of school COVID-19 cases (mask vs. no covering OR 2.82 (1.11, 7.14)) and was associated with higher self-reported cold symptoms. School staff reported the impacts of wearing face coverings on teaching, including having to stand closer to pupils and raise their voices to be heard. 67.1% were not able to implement 2-metre social distancing from pupils. We did not find evidence that maintaining a 2-metre distance was associated with lower rates of COVID-19 in the school. ConclusionsImplementing, adhering to and evaluating COVID-19 mitigation guidelines is challenging in primary school settings. Our findings suggest that reducing non-household direct contacts lowers infection rates. There was no evidence that face coverings, 2-metre social distancing or stopping children mixing was associated with lower odds of COVID-19 or cold infection rates in the school. Primary school staff found teaching challenging during COVID-19 restrictions, especially for younger learners and those with additional learning needs.

COVID-19 Infection Risk amongst 14,104 Vaccinated Care Home Residents: A national observational longitudinal cohort study in Wales, United Kingdom, December 2020 to March 2021 (preprint)

BackgroundVaccinations for COVID-19 have been prioritised for older people living in care homes. However, vaccination trials included limited numbers of older people. AimWe aimed to study infection rates of SARS-CoV-2 for older care home residents following vaccination and identify factors associated with increased risk of infection. Study Design and SettingWe conducted an observational data-linkage study including 14,104 vaccinated older care home residents in Wales (UK) using anonymised electronic health records and administrative data. MethodsWe used Cox proportional hazards models to estimate hazard ratios (HRs) for the risk of testing positive for SARS-CoV-2 infection following vaccination, after landmark times of either 7 or 21-days post-vaccination. We adjusted hazard ratios for age, sex, frailty, prior SARS-CoV-2 infections and vaccination type. ResultsWe observed a small proportion of care home residents with positive PCR tests following vaccination 1.05% (N=148), with 90% of infections occurring within 28-days. For the 7-day landmark analysis we found a reduced risk of SARS-CoV-2 infection for vaccinated individuals who had a previous infection; HR (95% confidence interval) 0.54 (0.30,0.95), and an increased HR for those receiving the Pfizer-BioNTECH vaccine compared to the Oxford-AstraZeneca; 3.83 (2.45,5.98). For the 21-day landmark analysis we observed high HRs for individuals with low and intermediate frailty compared to those without; 4.59 (1.23,17.12) and 4.85 (1.68,14.04) respectively. ConclusionsIncreased risk of infection after 21-days was associated with frailty. We found most infections occurred within 28-days of vaccination, suggesting extra precautions to reduce transmission risk should be taken in this time frame.

Intensity of COVID-19 in care homes following Hospital Discharge in the early stages of the UK epidemic (preprint)

Background A defining feature of the COVID-19 pandemic in many countries was the tragic extent to which care home residents were affected, and the difficulty preventing introduction and subsequent spread of infection. Management of risk in care homes requires good evidence on the most important transmission pathways. One hypothesised route at the start of the pandemic, prior to widespread testing, was transfer of patients from hospitals, which were experiencing high levels of nosocomial events. Methods We tested the hypothesis that hospital discharge events increased the intensity of care home cases using a national individually linked health record cohort in Wales, UK. We monitored 186,772 hospital discharge events over the period March to July 2020, tracking individuals to 923 care homes and recording the daily case rate in the homes populated by 15,772 residents. We estimated the risk of an increase in cases rates following exposure to a hospital discharge using multi-level hierarchical logistic regression, and a novel stochastic Hawkes process outbreak model. Findings In regression analysis, after adjusting for care home size, we found no significant association between hospital discharge and subsequent increases in care home case numbers (odds ratio: 0.99, 95% CI 0.82, 1.90). Risk factors for increased cases included care home size, care home resident density, and provision of nursing care. Using our outbreak model, we found a significant effect of hospital discharge on the subsequent intensity of cases. However, the effect was small, and considerably less than the effect of care home size, suggesting the highest risk of introduction came from interaction with the community. We estimated approximately 1.8% of hospital discharged patients may have been infected. Interpretation There is growing evidence in the UK that the risk of transfer of COVID-19 from the high-risk hospital setting to the high-risk care home setting during the early stages of the pandemic was relatively small. Although access to testing was limited to initial symptomatic cases in each care home at this time, our results suggest that reduced numbers of discharges, selection of patients, and action taken within care homes following transfer all may have contributed to mitigation. The precise key transmission routes from the community remain to be quantified.

Staff-Pupil SARS-CoV-2 Infection Pathways in Schools: A Population Level Linked Data Approach (preprint)

Abstract Background: Better understanding of the role that children and school staff play in the transmission of SARS-CoV-2 is essential to guide policy development on controlling infection whilst minimising disruption to children's education and wellbeing. Methods: Our national e-cohort (n=500,779) study used anonymised linked data for pupils, staff and associated households linked via educational settings. We estimated the risk of testing positive for SARS-CoV-2 infection for staff and pupils over the period August-December 2020, dependent on measures of recent exposure to known cases linked to their educational settings. Results: The total number of cases in a school was not associated with a subsequent increase in the risk of testing positive (Staff OR per case 0.92, 95%CI 0.85, 1.00; Pupils OR per case 0.98, 95%CI 0.93, 1.02). Amongst pupils, the number of recent cases within the same year group was significantly associated with subsequent increased risk of testing positive (OR per case 1.12, 95%CI 1.08 - 1.15). These effects were adjusted for a range of demographic covariates, and in particular any known cases within the same household, which had the strongest association with testing positive (Staff OR 39.86, 95%CI 35.01, 45.38, pupil OR 9.39, 95%CI 8.94 - 9.88). Conclusions: In a national school cohort, the odds of staff testing positive for SARS-CoV-2 infection were not significantly increased in the 14-day period after case detection in the school. However, pupils were found to be at increased risk, following cases appearing within their own year group, where most of their contacts occur. Strong mitigation measures over the whole of the study period may have reduced wider spread within the school environment.

Real-time spatial health surveillance: mapping the UK COVID-19 epidemic (preprint)

The COVID-19 pandemic has highlighted the need for robust data linkage systems and methods for identifying outbreaks of disease in near real-time. Using self-reported app data and the Secure Anonymised Information Linkage (SAIL) Databank, we demonstrate the use of sophisticated spatial modelling for near-real-time prediction of COVID-19 prevalence at small-area resolution to inform strategic government policy areas. A pre-requisite to an effective control strategy is that predictions need to be accompanied by estimates of their precision, to guard against over-reaction to potentially spurious features of best guess predictions. In the UK, important emerging risk-factors such as social deprivation or ethnicity vary over small distances, hence risk needs to be modelled at fine spatial resolution to avoid aggregation bias. We demonstrate that existing geospatial statistical methods originally developed for global health applications are well-suited to this task and can be used in an anonymised databank environment, thus preserving the privacy of the individuals who contribute their data.

The Impact of COVID-19 on Adjusted Mortality Risk in Care Homes for Older Adults in Wales, United Kingdom: A retrospective population-based cohort study for mortality in 2016-2020 (preprint)

BackgroundMortality in care homes has had a prominent focus during the COVID-19 outbreak. Multiple and interconnected challenges face the care home sector in the prevention and management of outbreaks of COVID-19, including adequate supply of personal protective equipment, staff shortages, and insufficient or lack of timely COVID-19 testing. Care homes are particularly vulnerable to infectious diseases. AimTo analyse the mortality of older care home residents in Wales during COVID-19 lockdown and compare this across the population of Wales and the previous 4-years. Study Design and SettingWe used anonymised Electronic Health Records (EHRs) and administrative data from the Secure Anonymised Information Linkage (SAIL) Databank to create a cross-sectional cohort study. We anonymously linked data for Welsh residents to mortality data up to the 14th June 2020. MethodsWe calculated survival curves and adjusted Cox proportional hazards models to estimate hazard ratios (HRs) for the risk of mortality. We adjusted hazard ratios for age, gender, social economic status and prior health conditions. ResultsSurvival curves show an increased proportion of deaths between 23rd March and 14th June 2020 in care homes for older people, with an adjusted HR of 1{middle dot}72 (1{middle dot}55, 1{middle dot}90) compared to 2016. Compared to the general population in 2016-2019, adjusted care home mortality HRs for older adults rose from 2{middle dot}15 (2{middle dot}11,2{middle dot}20) in 2016-2019 to 2{middle dot}94 (2{middle dot}81,3{middle dot}08) in 2020. ConclusionsThe survival curves and increased HRs show a significantly increased risk of death in the 2020 study periods.