A rise in the number of potentially fatal heart infections in people who inject drugs correlates with the growing use of a specific opioid named hydromorphone, according to a new study by London researchers.
By examining data from more than 60,000 Ontario hospital admissions related to injection drug use between 2006 and 2015, researchers discovered the risk of endocarditis increased from 13.4 admissions to 35.1 admissions every three months even though admission rates remained stable.
“We wondered if a change in the types of drugs people inject was responsible for this higher risk,” said Dr. Matthew Weir. He’s an adjunct scientist at ICES, and associate scientist at Lawson and an assistant professor at Schulich School of Medicine & Dentistry at Western University.
Through further analysis of the de-identified hospital data, the research team — which brought together people from all three institutions — discovered a parallel between the time that people who inject drugs faced higher risk of endocarditis, and a rise in hydromorphone prescriptions.
Hydromorphone made up 16 per cent of all opioid prescriptions in 2006, and was up to 53 per cent by 2015.
Researchers initially thought the increased risk for infective endocarditis would begin when controlled-release oxycodone was taken off the market in 2011, but discovered a substantial increase in the heart disease starting in 2010 instead.
“While the timing was not what we expected, we did find a correlation between the rise in infective endocarditis and hydromorphone prescriptions,” says Dr. Sharon Koivu, Lawson scientist and associate professor at Schulich Medicine & Dentistry.
Controlled-release oxycodone was easily dissolvable, and people using it didn’t save or reuse their needles. Controlled-release hydromorphone on the other hand, is more difficult to dissolve. Because residue stays on the injection equipment, people will save it for future use or share with others, giving bacteria multiple opportunities to spread and cause life-threatening damage to the lining of a person’s heart, according to researchers.
The research team continues to study whether bacteria that causes the illness is more likely to survive in equipment used to prepare hydromorphone, compared to other drugs.
“The opioid crisis is one of the most pressing health issues of our time. Our findings not only confirm an increasing risk of infective endocarditis in persons who inject drugs but also offer the first evidence for why it might be happening,” says Dr. Weir.
“Through research and collaboration, we hope to further collect the evidence needed to address this global problem.”
The study was published Monday in the Canadian Medical Association Journal.