Risk of overdose : do those who witness most overdoses also experience most overdoses?

One hundred and sixteen methadone maintenance clients were interviewed about experiences of personal and witnessed overdoses. Almost half (n = 57, 49%) had experienced 201 personal overdoses, 10 of whom (17.5%) had overdosed in the previous year. Over four-fifths of the sample (n = 98, 85%) had witnessed an overdose, and 35 had witnessed 109 fatalities. Categories were created to differentiate between those who had experienced high and low numbers of (1) personal, (2) witnessed non-fatal and (3) witnessed fatal overdoses. For personal overdose, the high-rate group had used alcohol more often. For witnessed non-fatal overdose, the high-rate group had witnessed more non-fatal and fatal overdoses; and for fatal witnessed overdoses, the high rate-group had used crack cocaine more often and witnessed more non-fatal overdoses. An association was found between injecting and personal and witnessed non-fatal overdose. There is a 'high-risk' group of drug users who experience most personal and witnessed overdoses. Overdoses are serious and frequent problems and appropriate interventions should be strengthened.