Drug injection may cause substantial rise in bacterial heart infections

A new study now finds that people who inject drugs have a significant increase in the risk of infective endocarditis. It is a serious infection of the lining of the heart and is possibly linked to increased use of the opioid hydromorphone.

The study is published in Canadian Medical Association Journal (CMAJ).

Speaking about the study, first author Dr, Matthew Weir wrote, "We observed a substantial increase in the risk of infective endocarditis among people who inject drugs, which is associated with hydromorphone's increasing share of the prescription opioid market."

The study further found that although admission rates for people who inject drugs were stable over the study period, the risk of infective endocarditis increased from 13.4 admissions every three months (fourth quarter 2011) to 35.1 admissions every three months in the period afterwards.

Whereas the percentage of opioid prescriptions attributed to controlled-release oxycodone declined rapidly when it was removed from the market by its manufacturer in the fourth quarter of 2011, hydromorphone prescriptions increased from 16 per cent at the start of the study to 53 per cent by the end.

The researchers expected that an increase in risk of infective endocarditis would occur when controlled-release oxycodone was removed from the Canadian market; however, they found that the rise began before removal.

Speaking about it, co-author Dr. Michael Silverman said, "Although our observations do not support our hypothesis that the loss of controlled-release oxycodone increased the use of hydromorphone, they do support our suspicion that hydromorphone may be playing a role in the increasing risk of infective endocarditis."

The increase in the risk of infective endocarditis is consistent with the findings of other studies, but the observed timing of the increase was novel.