Development of a proto-typology of opiate overdose onset

The time available to act is a crucial factor affecting the probable success of interventions to manage opiate overdose. We analyse opiate users' accounts of non-fatal overdose incidents to (i) construct a proto-typology of non-fatal opiate overdose onset and (ii) assess the implications for overdose management and prevention of fatalities.

Re-analysis of a subset of data from a large qualitative study of non-fatal opiate overdose conducted from 1997 to 1999. Data were generated from semi-structured interviews undertaken with opiate users who had experienced a non-fatal overdose in the previous 24 hours. Forty-four participants (30 men; 14 women; aged 16-47 years) provided sufficient information for in-depth analysis. Data relating to 'memory of the moment of overdose', 'time to loss of consciousness' and 'subjective description of the overdose experience' were scrutinised using iterative categorization.

Four types of overdose onset were identified: type A 'amnesic' (n = 8), characterized by no memory, rapid loss of consciousness and no description of the overdose experience; type B 'conscious' (n = 17), characterized by some memory, sustained consciousness and a description of the overdose in terms of feeling unwell and symptomatic; type C 'instant' (n = 14), characterized by some memory, immediate loss of consciousness and no description of the overdose experience; and type D 'enjoyable' (n = 5), characterized by some memory, rapid loss of consciousness and a description of the overdose experience as pleasant or positive.

The identification of different types of overdose onset highlights the complexity of overdose events, the need for a range of interventions and the challenges faced in managing incidents and preventing fatalities. Opiate overdose victims who retain consciousness for a sustained period and recognize the negative signs and symptoms of overdosing could summon help or self-administer naloxone, thus indicating that opiate overdose training should incorporate self-management strategies.