You need data on deaths and data on non-fatal overdoses. The data on deaths should come from the regional coroners, who should be empowered to collect data in real time and report it in real time. You can't fix what you're not even measuring. The information on non-fatal overdoses should come, I think, primarily from CIHI, which contains national records on emergency department and hospital visits. Those two things together, I think, will give you a pretty clear picture of the problem.
Do you want to add to that?