Unspecified opioids among opioid overdoses in Oslo, Norway.

Among 2381 included cases, 459 (19.3%) involved unspecified opioids, 134 (5.6%) long-acting opioids, and 1788 (75.1%) heroin. Overdoses involving unspecified opioids needed longer observation, median 5 h 29 min vs. 4 h 54 min (long-acting opioids) and 4 h 49 min (heroin) (p < 0.001), and had a lower Glasgow coma scale score, median 10 vs. 13 in both the other groups (p < 0.001). Naloxone was given in 23.3% of cases involving unspecified opioids, vs. 12.7% involving long-acting opioids and 30.2% involving heroin (p < 0.001). A larger proportion of patients were transferred to hospital care when unspecified or long-acting opioids were involved compared to heroin, 16.3% and 18.7% respectively vs. 10.1% (p < 0.001). Our results indicate that the category "unspecified opioids" encompasses a substantial proportion of opioids acting longer than heroin.