The definitions of adverse reaction and serious adverse reaction are in the regulations. A serious adverse reaction does involve hospitalization, but it involves several other things as well: if there is a life-threatening reaction; a death, obviously; a disability; or a congenital anomaly. Those are internationally harmonized definitions of serious adverse reactions. They're not Canadian only.
As was discussed previously, we are attempting wherever possible to harmonize this internationally, because we need to be able to merge the data. If someone has coded something in their database as serious, based on a different definition, and we're not using the same definition, it makes it impossible to come up with a summary to know what its significance is and to use numeric comparators—what we call proportional representation index numbers—to be able to say that one report makes any difference in the context of all the other reports in that class of drugs, or all of the drugs reported.
I hope that addresses your issue about what is serious.
As for how we would know there were other things going on, in addition to working with our foreign partners to be able to identify trends.... That is what adverse reaction reports are; they are not individual. They're not like CSI or a coroner's report—and some of them may be coroners' reports—but are used for trending, which is studied more intensively and may involve a study—