Modelling of hypothetical SARS-CoV-2 point of care tests for routine testing in residential care homes: rapid cost-effectiveness analysis.

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus that causes coronavirus disease 2019 (COVID-19), which at the time of writing (January 2021) was responsible for more than 2.25 million deaths worldwide and over 100,000 deaths in the UK. SARS-CoV-2 appears to be highly transmissible and could rapidly spread in residential care homes.

OBJECTIVE

The work undertaken aimed to estimate the clinical effectiveness and cost-effectiveness of viral detection point-of-care tests for detecting SARS-CoV-2 compared with laboratory-based tests in the setting of a hypothetical care home facility for elderly residents.

PERSPECTIVE/SETTING

The perspective was that of the NHS in 2020. The setting was a hypothetical care home facility for elderly residents. Care homes with en suite rooms and with shared facilities were modelled separately.

METHODS

A discrete event simulation model was constructed to model individual residents and simulate the spread of SARS-CoV-2 once it had entered the residential care facility. The numbers of COVID-19-related deaths and critical cases were recorded in addition to the number of days spent in isolation. Thirteen strategies involving different hypothetical SARS-CoV-2 tests were modelled. Recently published desirable and acceptable target product profiles for SARS-CoV-2 point-of-care tests and for hospital-based SARS-CoV-2 tests were modelled. Scenario analyses modelled early release from isolation based on receipt of a negative SARS-CoV-2 test result and the impact of vaccination. Incremental analyses were undertaken using both incremental cost-effectiveness ratios and net monetary benefits.

RESULTS

Cost-effectiveness results depended on the proportion of residential care facilities penetrated by SARS-CoV-2. SARS-CoV-2 point-of-care tests with desirable target product profiles appear to have high net monetary benefit values. In contrast, SARS-CoV-2 point-of-care tests with acceptable target product profiles had low net monetary benefit values because of unnecessary isolations. The benefit of allowing early release from isolation depended on whether or not the facility had en suite rooms. The greater the assumed efficacy of vaccination, the lower the net monetary benefit values associated with SARS-CoV-2 point-of-care tests, when assuming that a vaccine lowers the risk of contracting SARS-CoV-2.

LIMITATIONS

There is considerable uncertainty in the values for key parameters within the model, although calibration was undertaken in an attempt to mitigate this. Some degree of Monte Carlo sampling error persists because of the timelines of the project. The example care home simulated will also not match those of decision-makers deciding on the clinical effectiveness and cost-effectiveness of introducing SARS-CoV-2 point-of-care tests. Given these limitations, the results should be taken as indicative rather than definitive, particularly the cost-effectiveness results when the relative cost per SARS-CoV-2 point-of-care test is uncertain.

CONCLUSIONS

SARS-CoV-2 point-of-care tests have considerable potential for benefit for use in residential care facilities, but whether or not this materialises depends on the diagnostic accuracy and costs of forthcoming SARS-CoV-2 point-of-care tests.

FUTURE WORK

More accurate results would be obtained when there is more certainty on the diagnostic accuracy of and the reduction in time to test result associated with SARS-CoV-2 point-of-care tests when used in the context of residential care facilities, the proportion of care home penetrated by SARS-CoV-2 and the levels of immunity once vaccination is administered. These parameters are currently uncertain.

FUNDING

This report was commissioned by the National Institute for Health Research (NIHR) Evidence Synthesis programme as project number 132154. This project was funded by the NIHR Health Technology Assessment programme and will be published in full in

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus that causes coronavirus disease 2019 (COVID-19). SARS-CoV-2 is highly infectious, and this can cause problems in care homes, where the virus can spread quickly. Laboratory-based tests can determine whether or not someone has SARS-CoV-2, but these tests are not perfect and can take a long time to provide a result. Point-of-care tests that can be performed quickly in the care home to detect SARS-CoV-2 are being developed and they may have much shorter times to get a result than laboratory-based tests, although with worse accuracy. The benefit of quicker tests is that decisions to put residents into or release them from isolation can be made sooner, reducing the risk of spreading SARS-CoV-2 and reducing time in isolation. The disadvantage of reduced accuracy is that wrong decisions could be made, resulting in either unnecessary isolation or increased spread of SARS-CoV-2. A computer model was built to explore the impact of using SARS-CoV-2 point-of-care tests for residents of care homes. The model estimated the number of SARS-CoV-2 infections, deaths due to COVID-19 and days in isolation. Strategies were run using different values, including the time to get a test result back, the accuracy of tests, the proportion of care homes where there is a case of SARS-CoV-2, whether residents were isolated individually or in groups and how well vaccines work. The results of the model indicated that point-of-care tests could be good if there was a large decrease in the time to get a test result back, if accuracy was high and if vaccination protection was moderate. However, the accuracy and speed of future point-of-care tests is uncertain. When newer SARS-CoV-2 tests are available, the model will allow an estimate of the clinical effectiveness and cost-effectiveness of the tests to be made.