Nationwide mammography screening participation in Denmark during the COVID-19 pandemic: An observational study
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Curated by eLife
eLife assessment
This article is of broad interest to public health researchers and to health policymakers in populations with national screening programs. It provides important knowledge on the impact of the COVID-19 pandemic on participation in mammography screening in Denmark by socio-economic indicators. The study provides convincing evidence for how the pandemic exacerbated disparities in breast cancer screening in Denmark.
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Abstract
In most of the world, the mammography screening programmes were paused at the start of the pandemic, whilst mammography screening continued in Denmark. We examined the mammography screening participation during the COVID-19 pandemic in Denmark.
Methods:
The study population comprised all women aged 50–69 years old invited to participate in mammography screening from 2016 to 2021 in Denmark based on data from the Danish Quality Database for Mammography Screening in combination with population-based registries. Using a generalised linear model, we estimated prevalence ratios (PRs) and 95% confidence intervals (CIs) of mammography screening participation within 90, 180, and 365 d since invitation during the pandemic in comparison with the previous years adjusting for age, year and month of invitation.
Results:
The study comprised 1,828,791 invitations among 847,766 women. Before the pandemic, 80.2% of invitations resulted in participation in mammography screening within 90 d, 82.7% within 180 d, and 83.1% within 365 d. At the start of the pandemic, the participation in screening within 90 d was reduced to 69.9% for those invited in pre-lockdown and to 76.5% for those invited in first lockdown. Extending the length of follow-up time to 365 d only a minor overall reduction was observed (PR = 0.94; 95% CI: 0.93–0.95 in pre-lockdown and PR = 0.97; 95% CI: 0.96–0.97 in first lockdown). A lower participation was, however, seen among immigrants and among women with a low income.
Conclusions:
The short-term participation in mammography screening was reduced at the start of the pandemic, whilst only a minor reduction in the overall participation was observed with longer follow-up time, indicating that women postponed screening. Some groups of women, nonetheless, had a lower participation, indicating that the social inequity in screening participation was exacerbated during the pandemic.
Funding:
The study was funded by the Danish Cancer Society Scientific Committee (grant number R321-A17417) and the Danish regions.
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Author Response
Reviewer #1 (Public Review):
In general, in the discussion, I miss two of the main points that led to suspend screening programs in most countries during the pandemic:
- protecting women from the risk of infection linked to attending a clinic during pandemic when health facilities were mostly attended by symptomatic people seeking care for Covid-19;
We agree. We have added this to the background and Discussion section (page 3, lines 76-78 & page 9, lines 296-299).
- the of health professionals because they were mostly involved in covid related activities: lack of radiologists (addressed to the emergency department to assure diagnoses of pneumonia), lack of anesthesiologists (due to the expansion of intensive care), thus risking not having timely surgical treatment; lack of screening organization personal for …
Author Response
Reviewer #1 (Public Review):
In general, in the discussion, I miss two of the main points that led to suspend screening programs in most countries during the pandemic:
- protecting women from the risk of infection linked to attending a clinic during pandemic when health facilities were mostly attended by symptomatic people seeking care for Covid-19;
We agree. We have added this to the background and Discussion section (page 3, lines 76-78 & page 9, lines 296-299).
- the of health professionals because they were mostly involved in covid related activities: lack of radiologists (addressed to the emergency department to assure diagnoses of pneumonia), lack of anesthesiologists (due to the expansion of intensive care), thus risking not having timely surgical treatment; lack of screening organization personal for invitations and phone calls (working on contact tracing).
We agree. We have added this to the background and Discussion section (page 3, lines 76-78 & page 9, lines 296-299).
Lacking the rationale for suspending screening, it is not clear to the reader how the Danish program afforded these issues and was able to maintain open the program.
We have elaborated on this in the Discussion section (page 296-299), arguing that Denmark may have partly decreased the issue of staff shortage due to e.g., a lower burden of COVID-19, use of laymen and medical student for testing and vaccinations and a high vaccine coverage.
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eLife assessment
This article is of broad interest to public health researchers and to health policymakers in populations with national screening programs. It provides important knowledge on the impact of the COVID-19 pandemic on participation in mammography screening in Denmark by socio-economic indicators. The study provides convincing evidence for how the pandemic exacerbated disparities in breast cancer screening in Denmark.
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Reviewer #1 (Public Review):
The paper describes a very interesting public health experience. The Danish breast cancer screening program is one of the few programs that never suspended its activity during the pandemic.
In general, in the discussion, I miss two of the main points that led to suspend screening programs in most countries during the pandemic: 1) protecting women from the risk of infection linked to attending a clinic during pandemic when health facilities were mostly attended by symptomatic people seeking care for Covid-19; 2) the of health professionals because they were mostly involved in covid related activities: lack of radiologists (addressed to the emergency department to assure diagnoses of pneumonia), lack of anesthesiologists (due to the expansion of intensive care), thus risking not having timely surgical …
Reviewer #1 (Public Review):
The paper describes a very interesting public health experience. The Danish breast cancer screening program is one of the few programs that never suspended its activity during the pandemic.
In general, in the discussion, I miss two of the main points that led to suspend screening programs in most countries during the pandemic: 1) protecting women from the risk of infection linked to attending a clinic during pandemic when health facilities were mostly attended by symptomatic people seeking care for Covid-19; 2) the of health professionals because they were mostly involved in covid related activities: lack of radiologists (addressed to the emergency department to assure diagnoses of pneumonia), lack of anesthesiologists (due to the expansion of intensive care), thus risking not having timely surgical treatment; lack of screening organization personal for invitations and phone calls (working on contact tracing). Lacking the rationale for suspending screening, it is not clear to the reader how the Danish program afforded these issues and was able to maintain open the program.
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Reviewer #2 (Public Review):
The manuscript "Nation-wide mammography screening participation in Denmark during the COVID-19 pandemic: An observational study" aims at assessing the impact of COVID-19 on the participation to the breast cancer national screening program in Denmark.
Using a cohort of almost one million women, the authors used ageneralised linear model to estimate the prevalence ratios of participation to the screening program within 3, 6, and 12 months since the start of the pandemic.
The high quality of the data used represents the strongest point of the study, which provided a strong, reliable basis on which conduct the analysis. Some limitations are related to the way the date of invitation (to the screening program) is handled, the vaccination status of the cohort of interest (information not available) and the …
Reviewer #2 (Public Review):
The manuscript "Nation-wide mammography screening participation in Denmark during the COVID-19 pandemic: An observational study" aims at assessing the impact of COVID-19 on the participation to the breast cancer national screening program in Denmark.
Using a cohort of almost one million women, the authors used ageneralised linear model to estimate the prevalence ratios of participation to the screening program within 3, 6, and 12 months since the start of the pandemic.
The high quality of the data used represents the strongest point of the study, which provided a strong, reliable basis on which conduct the analysis. Some limitations are related to the way the date of invitation (to the screening program) is handled, the vaccination status of the cohort of interest (information not available) and the transferability of the study to other countries, for different countries handled the pandemic in different ways.
The authors show that there was an overall slight decrease in screening participation despite the screening program remained open throughout the pandemic and discuss likely reasons of why that may have happened. Further, they identified that groups of women who were already characterised by low participation rates, experienced a further reduction in attending screening. Those were mostly composed by immigrants and low income individuals. They also discuss the barrier that language may have posed in relation to the distribution of guidelines form the government, as those were delivered in Danish.
In conclusion, the study indicates that social iniquity, which usually relates to disparity in screening participation, has been slightly exacerbated during the pandemic. Although the authors do not discuss in detail what the consequences of those findings can be, it would be interesting to assess (through a follow-up study) whether they will have an impact on the cancer incidence and, in particular, the staging of cancers at detection for the interested groups.
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