Prevalence of "High Risk" Opioid Use in Norway

"High-risk opioid users are a heterogeneous group that includes marginalised drug users with long-standing ‘careers’ of heroin use, as well as socially included persons who became addicted to opioids through excessive consumption of prescribed pharmaceuticals. The description of high-risk opioid use does not include stable patients in opioid substitution treatment (OST) or others using pharmaceutical opioids in accordance with a doctor’s prescription. Patients in OST who misuse prescribed drugs or other opioids than the prescribed one(s) shall be included, however. Furthermore, persons not included in OST who misuse prescribed opioids shall be included.

"In the Norwegian context, the mortality multiplier method was also used to estimate the number of high-risk opioid users, even though the method is not optimal. The definition will then be indirect: It is assumed that, for high-risk users of opioids, the risk of dying an opioid-related death is between 1.5 or 2.5 per 100 person-years. This is similar to the risk of dying a drug-related death among injecting drug users. The reason for this choice is that many injecting drug users are also high-risk opioid users. The number of opioid-related deaths was restricted to the 15–64 age group and excluded intentional deaths (suicides) and recreational users. The average for the years 2010 to 2012 shows that heroin was the cause of death for 47 per cent, methadone for 27 per cent, while, for 26 per cent, other opioids were the cause of death.

"Some patients in OST may have been included, but they cannot be identified. Around 9–10 per cent of OST patients reported having used morphine/heroin substances recently in addition to OST medication (Waal et al. 2013). With a total of 7,450 persons in OST in 2012, this amounts to approximately 700 persons with risky morphine/heroin use in OST. We do not know whether they were high-risk users, however, and we do not know the proportion of high-risk use of other opioids among patients in OST.

"The number of high-risk opioid users was estimated to be 7,700 persons, with a sensitivity interval from 6,200 to 10,300 persons. The estimate includes those with the highest risk of death or other serious consequences."