The indirect consequences of COVID-19

by:
Alice M. Jackson

The direct impact of the COVID-19 pandemic is easily measured, with many countries reporting the daily number of hospitalisations and fatalities attributed to the disease. Excess deaths (deaths within the total death toll above those that would have been expected if the crisis had not occurred) represent both the direct and the indirect impact of a pandemic. The measurement of excess deaths allows objective quantification of the extent and scale of the impact, even when methods for reporting deaths differ between regions or countries; for example, some countries only report COVID-19 deaths that occur in hospitals, while others only report deaths for patients that have tested positive for the virus. Reporting of excess deaths provides information about deaths that may be related to COVID-19, but are not captured through the reporting system, and also, crucially, about whether the pandemic has led to an increase (or decrease) in deaths from other causes.

There has been mounting concern that patients with cardiovascular disease, and in particular those with acute conditions such as ST-elevation myocardial infarction, might avoid seeking medical attention, leading to late presenting sequalae such as ventricular septal rupture or heart failure. In Scotland, the rate of deaths from cardiovascular disease peaked at around 17% higher than the preceding 5-year average shortly after the country’s lockdown measures were implemented, before starting to fall (1). Furthermore, 7% of the total excess deaths over a 5-week period were due to cardiovascular causes (2). Collated data from England and Wales, the Netherlands, Italy and New York State have also highlighted notable levels of excess mortality, not all attributable to COVID-19 (2). What is not clear is whether these excess deaths are due to unconfirmed or unsuspected COVID-19 infection in a high-risk population, whether, as feared, a change in health behaviours has resulted in patients not seeking treatment with symptoms suggestive of an acute cardiac condition, or to what extent both factors may be contributing.

The future impact of the pandemic is difficult to project. Even after immediate transmission is controlled, it is likely that there will be lasting effects on overall population mortality. In an analysis using linked primary and secondary care electronic records for just less than 4 million individuals in the UK, excess 1-year mortality was modelled under 3 different scenarios – full suppression, mitigation and ‘do nothing’ – assuming different levels of risk in each scenario based on underlying comorbidities (3). Excess deaths ranged from 2 in a full suppression scenario with a relative risk of 1.5, to 587 982 in a ‘do nothing’ scenario with a relative risk of 3.0.  Data such as these are essential to policy makers in order to understand and mitigate worst case scenarios.

Reporting of excess deaths provides a more accurate representation of the full effects of the pandemic and a better measure from which to draw international comparisons. Understanding exactly what contributes to these deaths is important if high-risk groups are to be identified and targeted with appropriate risk-modifying interventions. Although health services have been reorganised and redirected in order to cope with the pandemic, it is vital that the public are encouraged to access acute service as normal.

  • Figueroa JD, Brennan P, Theodoratou E et al. Trends in excess cancer and cardiovascular deaths in Scotland during the COVID-19 pandemic 30 December – 20 April suggest underestimation of COVID-19 related deaths. 6 May 2020. https://doi.org/10.1101/2020.05.02.20086231
  • Docherty K, Butt J, de Boer R et al. Excess deaths during the Covid-19 pandemic: an international comparison. 13 May 2020. https://doi.org/10.1101/2020.04.21.20073114
  • Banerjee A, Pasea L, Harris S et al. Estimating excess 1-year mortality associated with the COVID-19 pandemic according to underlying conditions and age: a population based cohort study. Lancet. 12 May 2020. https://doi.org/10.1016/S0140-6736(20)30854-0

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