AIMS: To assess whether people who inject drugs (PWID) and who are treated for overdose by ambulance services have a greater mortality risk compared with other PWID, and to compare mortality risk within potentially critical time-periods (1 week, 1 month, 3 months, 6 months, 1 year, 5 years) after an overdose attendance with the mortality risk within potentially non-critical time-periods (time before and/or after critical periods). DESIGN: A prospective cohort study. SETTING: Oslo, Norway. PARTICIPANTS: A total of 172 PWID street-recruited in 1997 and followed-up until the end of 2004. MEASUREMENTS: Interview data linked to data from ambulance records, Norwegian Correctional Services, Opioid Substitution Treatment records and National Cause of Death Registry. Separate Cox regression models (one for each critical time-period) were estimated. FINDINGS: Ambulance services treated 54% of the participants for an overdose during follow-up. The mortality rate was 2.8 per 100 person-years for those with an overdose and 3.3 for those without; the adjusted hazard ratio (HR) was 1.3 (95% CI = 0.6, 2.6, P = 0.482). Mortality risk was greater in all but the shortest critical time-period following ambulance attendance than in the non-critical periods. The mortality risk remained significantly elevated during critical periods, even when adjusted for total time spent in prison and substitution treatment. The HR ranged from 9.4 (95% CI = 3.5, 25.4) in the month after an overdose to 13.9 (95% CI = 6.4, 30.2) in the 5-year period. CONCLUSIONS: Mortality risk among people who inject drugs is significantly greater in time-periods after an overdose attendance than outside these time-periods.
AIMS: To assess whether people who inject drugs (PWID) and who are treated for overdose by ambulance services have a greater mortality risk compared with other PWID, and to compare mortality risk within potentially critical time-periods (1 week, 1 month, 3 months, 6 months, 1 year, 5 years) after an overdose attendance with the mortality risk within potentially non-critical time-periods (time before and/or after critical periods). DESIGN: A prospective cohort study. SETTING: Oslo, Norway. PARTICIPANTS: A total of 172 PWID street-recruited in 1997 and followed-up until the end of 2004. MEASUREMENTS: Interview data linked to data from ambulance records, Norwegian Correctional Services, Opioid Substitution Treatment records and National Cause of Death Registry. Separate Cox regression models (one for each critical time-period) were estimated. FINDINGS: Ambulance services treated 54% of the participants for an overdose during follow-up. The mortality rate was 2.8 per 100 person-years for those with an overdose and 3.3 for those without; the adjusted hazard ratio (HR) was 1.3 (95% CI = 0.6, 2.6, P = 0.482). Mortality risk was greater in all but the shortest critical time-period following ambulance attendance than in the non-critical periods. The mortality risk remained significantly elevated during critical periods, even when adjusted for total time spent in prison and substitution treatment. The HR ranged from 9.4 (95% CI = 3.5, 25.4) in the month after an overdose to 13.9 (95% CI = 6.4, 30.2) in the 5-year period. CONCLUSIONS: Mortality risk among people who inject drugs is significantly greater in time-periods after an overdose attendance than outside these time-periods.
Keywords:
Ambulance services; cohort study; data linkage; drug use; emergency services; injecting drug use; mortality; people who inject drugs; prehospital treatment