Modelling the impact of the coronavirus pandemic on bowel cancer screening outcomes in England: A decision analysis to prepare for future screening disruption

The impact of delayed screening colonoscopies during the COVID-19 pandemic on clinical outcomes

BACKGROUND

Colorectal cancer (CRC) screening services in Ireland were cancelled or postponed for periods during the COVID-19 pandemic. The aim of this study was to assess the impact of screening colonoscopy delays after a positive FIT on clinical and histopathological outcomes due to these restrictions.

METHODS

Participants in the Irish National Bowel Screening Programme with a positive Immunochemical Faecal Test (FIT) during the COVID-19 pandemic (March 2020-December 2021) were included. Patients were categorised into attended for a colonoscopy <3 months and attended for colonoscopy ≥3-17 months post positive FIT. Chi-Square Test of independence was performed using WinPepi.

RESULTS

3227 individuals had a complete index colonoscopy <3 months and 262 attended colonoscopy from ≥3 to 17 months post positive FIT. Of the clients whose colonoscopy was between ≥3-17 months from positive FIT, the median wait time was 3 months. There was no significant difference found between the two groups for CRC (5.8 % vs 5.0 %, p=0.544) or for the proportion of cancer stage I, stage II and unknown (33.7 %, 40.6 %, 25.7 %, p=0.411). There was no difference in the proportions of adenomas (57.8 % vs 58.4 %, p=0.849) and the proportion of advanced adenomas (7.7 % vs 10.7 %, p=0.077) detected between the two groups. A similar proportion of polyps were detected in individuals whose index colonoscopies were postponed <3 months from positive FIT (66.9 % vs 66 %, p=0.786).

CONCLUSION

A median delay of 3 months in screening colonoscopies after a positive FIT does not adversely impact clinical or histopathological outcomes. There was no significant difference in cancer staging, advanced adenomas or polyps detected between those who attended colonoscopies <3 months and ≥3-17 months post positive FIT. COVID-19 related disruptions to the normal functioning of the Irish bowel screening programme did not compromise our key objectives of advanced adenoma and cancer detection.

Effects on Cancer Prevention from the COVID-19 Pandemic

The COVID-19 pandemic led to disruption of health services around the world, including cancer services. We carried out a narrative review of the effect of the pandemic on cancer prevention services, including screening. Services were severely affected in the early months of the pandemic, and in some areas are still recovering. Large numbers of additional cancers or additional late-stage cancers have been predicted to arise over the coming years as a result of this disruption. To minimize the effects on cancer outcomes, it is necessary to return as quickly as possible to prepandemic levels of screening and prevention activity or indeed to exceed these levels. The recovery of services should address health inequalities.

Scoping review of modelling studies assessing the impact of disruptions to essential health services during COVID-19

BACKGROUND

Studies assessing the indirect impact of COVID-19 using mathematical models have increased in recent years. This scoping review aims to identify modelling studies assessing the potential impact of disruptions to essential health services caused by COVID-19 and to summarise the characteristics of disruption and the models used to assess the disruptions.

METHODS

Eligible studies were included if they used any models to assess the impact of COVID-19 disruptions on any health services. Articles published from January 2020 to December 2022 were identified from PubMed, Embase and CINAHL, using detailed searches with key concepts including COVID-19, modelling and healthcare disruptions. Two reviewers independently extracted the data in four domains. A descriptive analysis of the included studies was performed under the format of a narrative report.

RESULTS

This scoping review has identified a total of 52 modelling studies that employed several models (n=116) to assess the potential impact of disruptions to essential health services. The majority of the models were simulation models (n=86; 74.1%). Studies covered a wide range of health conditions from infectious diseases to non-communicable diseases. COVID-19 has been reported to disrupt supply of health services, demand for health services and social change affecting factors that influence health. The most common outcomes reported in the studies were clinical outcomes such as mortality and morbidity. Twenty-five studies modelled various mitigation strategies; maintaining critical services by ensuring resources and access to services are found to be a priority for reducing the overall impact.

CONCLUSION

A number of models were used to assess the potential impact of disruptions to essential health services on various outcomes. There is a need for collaboration among stakeholders to enhance the usefulness of any modelling. Future studies should consider disparity issues for more comprehensive findings that could ultimately facilitate policy decision-making to maximise benefits to all.

Potential global loss of life expected due to COVID-19 disruptions to organised colorectal cancer screening

Background

Screening for colorectal cancer (CRC) decreases cancer burden through removal of precancerous lesions and early detection of cancer. The COVID-19 pandemic has disrupted organised CRC screening programs worldwide, with some programs completely suspending screening and others experiencing significant decreases in participation and diagnostic follow-up. This study estimated the global impact of screening disruptions on CRC outcomes, and potential effects of catch-up screening.

Methods

Organised screening programs were identified in 29 countries, and data on participation rates and COVID-related changes to screening in 2020 were extracted where available. Four independent microsimulation models (ASCCA, MISCAN-Colon, OncoSim, and Policy1-Bowel) were used to estimate the long-term impact on CRC cases and deaths, based on decreases to screening participation in 2020. For countries where 2020 participation data were not available, changes to screening were approximated based on excess mortality rates. Catch-up strategies involving additional screening in 2021 were also simulated.

Findings

In countries for which direct data were available, organised CRC screening volumes at a country level decreased by an estimated 1.3-40.5% in 2020. Globally, it is estimated that COVID-related screening decreases led to a deficit of 7.4 million fewer faecal screens performed in 2020. In the absence of any organised catch-up screening, this would lead to an estimated 13,000 additional CRC cases and 7,900 deaths globally from 2020 to 2050; 79% of the additional cases and 85% of additional deaths could have been prevented with catch-up screening, respectively.

Interpretation

COVID-19-related disruptions to screening will cause excess CRC cases and deaths, but appropriately implemented catch-up screening could have reduced the burden by over 80%. Careful management of any disruption is key to improving the resilience of colorectal cancer screening programs.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by Cancer Council New South Wales, Health Canada, and Dutch National Institute for Public Health and Environment.