Patterns of excess mortality reported during the COVID-19 pandemic were remarkably diverse across Canadian provinces, data indicate. No single explanation is likely to account for all the variation.
An analysis of provincial data showed that rates of excess mortality in Alberta, British Columbia, and Saskatchewan, Canada, were nearly double those of other provinces.
“We have a lot to learn about what happened across provinces, and it's an opportunity to do so, so we can be prepared for the next health threat,” study author Kimberlyn McGrail, PhD, a professor in the school of population and public health at the University of British Columbia in Vancouver, Canada, told Medscape Medical News.
The findings were published online May 30 in the Canadian Medical Association Journal.
Examining Public Data
McGrail used publicly available data to quantify excess mortality related to COVID-19 in each province from the start of the pandemic in mid-March 2020 through late October 2021. She obtained weekly data on observed and expected deaths from Statistics Canada. Data on COVID-19 deaths were obtained from the COVID-19 in Canada dashboard, which reflects daily reporting by public health agencies in each province.
Compared with COVID-19–specific deaths, excess mortality may provide a more useful indicator of the pandemic's population-wide effects, according to McGrail. That’s because the statistic may account for other factors affected by the pandemic, such as delayed healthcare or surgeries, which could have led to poorer clinical outcomes and higher mortality.
Alberta, British Columbia, and Saskatchewan had between 150 and 180 excess deaths per 100,000 population from mid-March 2020 through late October of 2021 — nearly double the rates of other provinces.
By contrast, Quebec, Newfoundland and Labrador, and Manitoba had excess death rates of 50 or fewer per 100,000 population. Quebec had the highest COVID-19–specific mortality rate, according to McGrail.
Prince Edward Island and Nova Scotia had low COVID-19 rates and negative excess death rates.
Quebec and Nova Scotia had periods when excess deaths exceeded COVID-19 deaths, but there were also periods during which mortality rates were lower than expected, said McGrail.
Ontario and Saskatchewan had a few weeks when excess mortality rates were lower than expected, while in Alberta and British Columbia, excess mortality rates were consistently increased.
Ontario had the most consistent correlation between excess deaths and reported COVID-19 deaths, according to McGrail, though rates diverged somewhat in the summer and fall of 2021.
Finally, excess mortality rates in British Columbia, Alberta, and Saskatchewan far exceeded reported COVID-19 death rates early in the pandemic and close to the end of the reported period, she said, including a huge spike in excess deaths in British Columbia coinciding with the 2021 heat dome.
"Forensic Analysis" Needed
Differences in COVID-19 data reporting between provinces could account for much of the variation, according to McGrail. However, differences in province-specific COVID-19 control measures may have played a role. Other health crises, such as the heat dome over British Columbia in the summer of 2021, make the excess death data more difficult to analyze.
In addition, emergency response to the heat dome could have been hampered by pandemic-related factors. “We were not congregating in large groups at that time, so there could have been things like cooling centers that didn't happen because of the pandemic,” McGrail said. “This is well beyond the scope of the paper here, but I think it’s fair to say that some of what happened during the heat dome could have been a COVID-related, rather than COVID-specific, event.”
Based on these findings, Canada’s health systems need to generate better and more consistent data, according to McGrail, who called for a “forensic analysis” of factors that contributed to mortality. That conversation needs to start now, she added, so that all stakeholders are ready and willing to respond to future public health crises.
David Naylor, MD, PhD, co-chair of Canada’s COVID-19 Immunity Task Force, said the findings emphasize the need to understand how and why there were substantial variations in excess deaths and deaths attributed to COVID-19.
“This is a signpost of the need for some critical self-appraisal on multiple fronts,” Naylor, who also is a professor of medicine at the University of Toronto, Toronto, Ontario, Canada, told Medscape. He was not involved in the study.
In addition to the disruption of services caused by the British Columbia heat wave, it would be important to determine whether longstanding health inequities, as well as inadequacies in long-term care and other health and social services, were magnified by the pandemic, said Naylor.
However, the most immediate need suggested by the current report, he said, is to understand how much of the province-by-province variation in excess and COVID-19 death rates stems from misclassification of cause of death, due to inconsistent and inadequate methods of tracking causes of deaths in Canada.
“Canada has had issues with the adequacy of its health information systems and death records for many years,” Naylor said.
“From a pandemic management perspective, we didn’t strengthen our death ascertainment methods to look more carefully for evidence of COVID-19 among persons dying in hospital or in the community, either routinely or with some strategic sampling,” he added.
More generally, most provinces still have weakly integrated healthcare and health information systems, according to Naylor.
“It’s way overdue to address all these longstanding problems,” he said.
The study was conducted without external funding. McGrail and Naylor reported no competing interests.
CMAJ. Published online May 30, 2022. Full text.
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