Determining cause of death not always an exact science
Sometimes COVID-19 causes death and sometimes it is a contributing factor, but not the direct cause
Last month, Canadians heard of unusually high numbers of deaths in China, Italy and Spain. Today, we eagerly await daily statistics, including the number of COVID-19 deaths affecting our own population. Some worry that the real numbers are being withheld, while others believe the entire pandemic is all just one big hoax.
If only the calculation was as simple as either.
Not many people understand how cause of death is determined, and probably even fewer understand how varied the process is from country to country, and even province to province. Understanding the basics of death certification and the death investigation system is important when interpreting death statistics.
In Canada, death investigation is the responsibility of each province and follows either the coroner’s system or medical examiner’s (ME) system. Most Canadians die of natural causes — cardiovascular disease or cancer, for example. The cause is usually unsurprising, and death certification is done by the individual’s most responsible physician shortly after death.
In cases of accident, homicide, suicide or when a cause of death cannot be easily determined, deaths are investigated by either a coroner or ME. In provinces that have a coroner system, coroners might be GPs or individuals with experience with death certification, but no formal medical training. In provinces with an ME system, a forensic pathologist completes the death certificate, and makes the decision whether to proceed to autopsy or not. Both systems have documented resource shortages.
Like most things in medicine, it is both a science and an art. Different systems may yield different results.
In either case, this information is important to families and sometimes important to the justice system. In a pandemic, this information becomes critical to public health tracking and health care planning. While COVID-19 deaths fall in the “natural” category, COVID-19 death statistics have become uniquely important and interesting.
We have without a doubt seen a significant increase in the number of Canadian care home deaths, associated with COVID-19 outbreaks. Our public health officers have ramped up testing and have been doing a wonderful job with reporting statistics and advice. It’s allowed for the identification of a critical trend in care homes.
But what is a “COVID-19 death” and did the patient die from COVID-19 or with COVID-19?
A recent COVID-19 autopsy study by pulmonary pathologist Dr. Sanjay Mukhopadhyay out of Cleveland Clinic demonstrated the point that determinations of death based on clinical information and COVID-19 swab testing alone are not an exact science. Determination of cause of death, even with autopsy, can be difficult. Most COVID-19 deaths in Canada won’t undergo autopsy, and this is might not be a major issue when someone presents with a positive test, classic radiologic findings and clinical course of deteriorating respiratory illness.
The study analyzed the clinical and autopsy information of two individuals who had positive COVID-19 swab tests in Oklahoma. The first was a 77-year-old man who had a number of complex medical issues. He had been experiencing weakness and chills for a number of days. EMS was called after he reported worsening shortness of breath. He died shortly after arrival to hospital.
His autopsy confirmed the presence of COVID-19 in his lungs and demonstrated microscopic lung damage. While the man showed signs of other underlying diseases, they were not deemed significant enough to explain his death, and the cause of death was listed as COVID-19 with his other conditions listed under “other contributing factors.”
The second case was a 42-year-old man with a known heart dystrophy. He was admitted to the hospital with “community acquired pneumonia” in critical condition and died while in hospital. While his COVID-19 swab was positive, his lungs did not test positive for COVID-19 and showed no microscopic evidence of the viral disease. He died with COVID-19, and not of COVID-19, and the autopsy was critical in making this distinction.
The practice of autopsy is an expensive and invasive medical test. In Canada, we do not have the resources and capacity — think staffing and personal protective equipment — to perform a complete autopsy on every “possible” COVID-19 death. Like any medical test, it is an important tool when a diagnosis, or in this case, a cause of death, cannot be easily ascertained.
Our system is doing its best to track vital statistics, and our experts are working around the clock to interpret trends in order to provide us with daily guidance. All statistics will have some bias or margin of error.
Canadians should continue to trust the interpretations of trends done by our experts. We can only start making sense of numbers once we have a better sense of how they are collected and compiled.
Death statistics are no exception.