NDARC Technical Report No. 58 (1998)
In order to determine the role played by heroin purity in fatal heroin overdoses, time series analyses were conducted on the purity of street heroin seizures in south western Sydney and overdose fatalities in that region. A total of 322 heroin samples were analysed by fortnightly periods between February 1993 to January 1995. A total of 61 overdose deaths occurred in the region in the study period, and were allocated to the appropriate fortnights. Alcohol was detected in 33% of cases, as were benzodiazapines.
Cross correlation plots revealed a significant correlation of 0.57 at time lag zero between mean purity of heroin samples per fortnight and number of overdose fatalities, accounting for 32% of the variance in fatalities. Similarly, there was a significant correlation of 0.50 at time lag zero between the highest heroin purity per fortnight and number of overdose fatalities, accounting for 25% of the variance in fatalities. The correlation between range of heroin purity and number of deaths per fortnight was 0.40, accounting for 16% of the variance in fatalaties. A simultaneous multiple regression on scores adjusted for first order correlation indicated both the mean level of heroin purity and the range of heroin purity were independent predictors of the number of deaths per fortnight.
Overall, the results indicate that the occurrence of overdose fatalities was moderately associated with both the average heroin purity and the range of heroin purity over the period 1993-1995.