Assessing the impact of testing for COVID-19 using lateral flow devices in NHS acute trusts in England
Authors: Chen Siyu , Hounsell Rachel , Cantrell Liberty , Tsui Lok Hei , Naidoo Reshania , Dahal Prabin , Creswell Richard , Bajaj Sumali , Flegg Jennifer A. , Fowler Tom , Hopkins Susan , Lambert Ben , Voysey Merryn , White Lisa J. ,   EY-Oxford Health Analytics Consortium, Stepniewska Kasia , Shretta Rima 
Published: June 2024

Background

Twice-weekly lateral flow device (LFD) testing was introduced for routine asymptomatic testing of healthcare workers (HCWs) in the National Health Service (NHS) in England in November 2020, with the primary aim of reducing nosocomial infections among staff and patients and a secondary aim of reducing absenteeism among HCWs. Here, we describe the burdens of HCW absenteeism and nosocomial infections in NHS acute trusts and the reported testing intensity of LFDs and associated costs from October 2020 to March 2022 and assess the impact of LFD testing on reducing these burdens.

Methods and Findings

We collected 16 million LFD testing results (total cost GBP 1.64 billion) reported in NHS acute trusts through England’s Pillar 1 and 2 testing programmes from 1 October 2020 to 30 March 2022. We estimated the prevalence of nosocomial COVID-19 infections in NHS acute trusts using data from the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC). Testing data were linked with nosocomial infections and full-time equivalent (FTE) days lost by trust for NHS acute trusts.

We used a mixed-effects linear model to examine the association between FTE days lost and LFD test coverage. The relationship between weekly prevalence of nosocomial infections and LFD test coverage in the previous week was modelled using logistic regression weighted by the number of new COVID-19 cases reported in the ISARIC dataset for that week. We adjusted both models for community prevalence of COVID-19 infections, average income deprivation score, prevalence of variants of concern and LFD test positivity.

FTE days lost among HCWs varied considerably by trust type, staff group, geographical location of trusts, and progress of the pandemic in England. Increased LFD test coverage was associated with decreases in FTE days lost due to COVID-19 from November 2020 to July 2021, with no association observed from August 2021 to March 2022. Higher community prevalence levels were associated with significant increases in FTE days lost due to COVID-19 in all periods except the pre-vaccination period (last two months of 2020). The model predicted that changes in testing levels (50–150%) would have resulted in modest changes in FTE days lost due to COVID-19 for all time periods.

We identified 3,794 nosocomial infections (if patients developed COVID-19 symptoms 7 days or more after their hospital admission) among 106,377 hospitalised COVID-19 patients in 136 NHS acute trusts. The proportion of nosocomial infections among new weekly cases in hospitalised patients was negatively associated with reported LFD testing levels. The strength of the association varied over time and was estimated to be highest during the Omicron period, although no effect of testing on HCW absenteeism was found. The observed HCW testing/reporting was estimated to be associated with a 16.8% (95% confidence interval 8.2%, 18.8%) reduction in nosocomial infections compared with a hypothetical testing scenario at 25% of actual levels, translating to a cost saving per quality-adjusted life-year (QALY) gained of GBP 18,500–46,400.

Conclusions

LFD testing was an impactful public health intervention for reducing HCW absenteeism and nosocomial infections in NHS acute trusts and was cost effective in preventing nosocomial infections.

Author Summary

Why was this study done?

In any pandemic response, mass diagnostic testing plays a key role.

We sought to evaluate the burdens of healthcare worker absenteeism and nosocomial infections in NHS acute trusts, the reported testing intensity using lateral flow devices (LFDs) and associated costs, and the impact of LFD testing on reducing these burdens.

What did the researchers do and find?

We collected 16 million LFD testing results and full-time equivalent (FTE) days lost due to COVID-19, obtained from healthcare workers (HCWs) in NHS acute trusts in England between 1 October 2020 and 30 March 2022.

We estimated the number of nosocomial COVID-19 infections in NHS acute trusts using data from the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC).

Testing data were linked with nosocomial infections and FTE days lost due to COVID-19 by trust for NHS acute trusts.

We used a mixed-effects linear model to examine the association between FTE days lost due to COVID-19 and LFD test coverage and applied a logistic regression to assess the association between nosocomial infections and LFD test coverage.

We found that LFD testing in the healthcare setting was an impactful public health intervention.

LFD testing reduced HCW absenteeism and nosocomial infections in NHS acute trusts; it was also cost effective in preventing nosocomial infections.

What do these findings mean?

Our analysis of the available data indicated that testing HCWs had varying impacts (on both nosocomial infections and HCW FTE days lost due to COVID-19) throughout the pandemic, possibly influenced by external factors such as community prevalence and vaccination.

In any future pandemic, HCW testing interventions should incorporate collection of and/or timely access to relevant data, including HCW absenteeism, routine test results, community prevalence, and hospitalisation and mortality data.

The lessons learnt from this study could be used by relevant authorities to support the real-time assessment of any testing service and adjustment of the testing regimen; they could also be used to help develop more targeted and agile testing systems, which operationally would require the ability to turn mass testing off and on as an epidemic progressed.