Identifying and evaluating patterns of prescription opioid use and associated risks in Ontario, Canada

Opioid prescribing and related adverse events are one of the key public health issues facing policy-makers in both the United States and Canada, leading to the loss of tens of thousands of lives annually. The core objective of this thesis was to inform and evaluate related drug-policy decision-making in Canada. This was accomplished by first describing patterns and public health impact of fatal opioid overdoses in Ontario. These studies described the growing rate of fatal opioid overdoses in Ontario, and the fact that these deaths are usually accidental in nature, are clustered among a younger demographic, and involve both opioids and other CNS depressants. Next, we investigated the relationship between patterns of opioid use and adverse events. We found that increasing opioid doses are associated with fatal overdose deaths and risk of being injured in a motor vehicle accident when driving. Furthermore, we found a significantly increased risk of opioid-related death among patients concomitantly using opioids and gabapentin. Finally, we explored the impact of new opioid formulations and legislation on opioid dispensing and adverse events. In these studies, we found indications of elevated OxyContin® dispensing at Ontario pharmacies near the Detroit-Windsor tunnel following the introduction of tamper-deterrent long-acting oxycodone in the United States, but no similar shifts in dispensing patterns upon the introduction of generic long-acting oxycodone in Canada several years later. Furthermore, we found that legislation introduced in Ontario had a significant impact on inappropriate prescribing of opioids, but no impact on rates of hospital visits for opioid overdoses.