Postdoctoral researcher developing tool to measure medication-related cardiovascular vulnerability during extreme weather

The 2021 heat dome in British Columbia killed 619 people. More than 90 per cent of the victims were age 60 and older, and nearly one-third had underlying ischemic heart disease. 

According to the Canadian Climate Institute, extreme heat waves across Canada are happening more frequently, lasting longer, and reaching higher temperatures than in previous decades. For the one in 12 Canadian adults living with heart disease, these heat events pose a significant risk to cardiovascular health.

Some medications, like beta blockers, diuretics, and certain antidepressants or antipsychotics, can make it harder for the body to cope with extreme temperatures. Some may affect heart rate and circulation, others can increase the risk of dehydration, reduce sweating, or interfere with the body’s ability to regulate temperature. 

Doctors know the risk of taking a single medication, but there isn’t a simple tool to determine cumulative risk for patients taking multiple medications. 

Dr. Henry Michael, PhD, a postdoctoral scholar supervised by Dr. Tolu Sajobi, PhD, wants to change that.

“This matters because many older adults with heart disease use five to seven medicines,” says Michael. 

Michael, a pharmacist-scientist, recently participated in the Canadian Institutes of Health Research’s Institute of Aging’s Summer Program in Aging, a prestigious training program that brings together about 40 trainees from across Canada.  

“This year’s focus was on the impact of climate change on the health of older persons, and the summer program made me think of climate vulnerability differently,” says Michael. “I realized that it’s a complex problem, with many factors. Medication is one, but there are other factors, including socio-economic, that make a difference in how an individual deals with environmental stressors.” 

The project that landed Michael a spot in the prestigious summer program involves developing a Thermoregulatory Medication Burden Score, which combines the effects of multiple medicines on heat and cold tolerance. The proposed score will be built and tested using heart disease data and pharmacy records from Alberta patients and linked to local weather from 2004 to 2019.

The hope is that providing a clear score will help clinicians and public health teams identify who may need extra support and target the right interventions at the right time during extreme weather. 

“The goal is earlier counselling, safer medication plans, and faster support during alerts, so older Canadians with heart disease face less risk when extreme weather strikes,” says Michael. 

Investigating beyond the individual

The work is a natural extension of Michael’s broader research into how vulnerability is measured.

His postdoctoral research involves developing and validating frailty indices in patients with coronary artery disease with the goal of improving risk prediction.

Frailty reflects a person’s reduced physiological reserve and their ability to bounce back from illness or other stressors. Although frailty is associated with aging, Michael says it is also highly individual. Two people who are the same age can have very different levels of resilience and vulnerability.

“It’s a multi-domain index,” says Michael, explaining that frailty can include factors such as physical function, comorbidities, and cognition, while gender, social and cultural factors can also shape a person’s vulnerability.

That idea of looking at the whole person is what led him to think about climate vulnerability in a similar way.

“In medicine, we often try to put people in boxes,” he says. “For example, there’s a thought that if you are over 65, you are vulnerable. But we know that no two older adults are the same.”

From pharmacist to scientist

Michael’s interest in solving these larger questions began during his career as a pharmacist in Nigeria.

He earned his undergraduate degree in pharmacy and worked as a practicing pharmacist for five years before completing a master’s degree in pharmacology. He later completed a PhD in pharmacology in South Africa and a second PhD in experimental medicine at McGill University in Montreal.

His second PhD focused on medication burden and its relationship with frailty and cognitive health in people aging  with HIV.

Working directly with patients in Nigeria also shaped the way Michael thinks about research.

“I was working in Nigeria, where you see people facing a lot of health challenges, often in settings with limited resources available to help,” he says.

Eventually, Michael became frustrated with trying to solve complex problems one patient at a time.

“At the time, I got tired of trying to solve the problems at the individual level, and I knew I was not going to be able to do that without being a scientist,” says Michael. 

That desire to understand the bigger picture has followed him throughout his career, from research into medication use, HIV and aging to cardiovascular disease and climate vulnerability.

“I want to solve the problems,” he says.

Michael’s current work brings those interests together. By combining medication data with information about patients, their health and the environment around them, he hopes to develop better ways of identifying who is most vulnerable when extreme temperatures occur.

Ultimately, he sees measurement science to move beyond broad categories and toward a better understanding of the individual.

The Thermoregulatory Medication Burden Score is still in development, but Michael hopes it can eventually become a practical tool for clinicians and public health teams that helps them identify medication-vulnerable patients and provide support before extreme weather becomes a health emergency.