Fluctuations in heroin purity and the incidence of fatal heroin overdose

https://doi.org/10.1016/S0376-8716(98)00159-8Get rights and content

Abstract

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 in fortnightly periods between February 1993 to January 1995. A total of 61 overdose deaths occurred in the region in the study period. 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. 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. The correlation between range of heroin purity and number of deaths per fortnight was 0.40. 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. 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 study period.

Introduction

Deaths attributed to overdose remain the largest contributor to excess mortality associated with heroin use (Cottrell et al., 1985, Oppenheimer et al., 1994, O'Doherty and Farrington, 1997). Excess mortality rates have been estimated to be 13 times those expected among peers of the same age and gender (English et al., 1995), although excess mortality rates as high as 22 have been reported among this population (Frischer et al., 1997). In Australia, the incidence of fatal heroin overdose has increased from 10.7 per million in 1979 to 67.0 per million in 1995, representing a rise from 70 deaths in 1979 to 550 in 1995 (Hall and Darke, 1998). A sharp increase in opioid-related mortality has also been reported elsewhere (De la Fuente et al., 1995, Sanchez et al., 1995).

The causes of heroin overdose, and the rise in overdose fatalities remain unclear (Darke and Zador, 1996). The classical depiction of a fatal `overdose', as the result of a quantity or quality (purity) of heroin in excess of the person's current tolerance to the drug, is the most long-standing and widely accepted explanation for death due to heroin. A natural consequence of this view is that fluctuations in heroin purity (the diamorphine content of the drug) are seen as a major cause of heroin-related deaths. Media reports regularly speak of `killer heroin' batches of unusual purity. Heroin users themselves believe that variations in purity are the major cause of non-fatal and fatal overdoses (Darke et al., 1996).

Others, however, dispute the primacy given to the role of heroin per se, and of heroin purity, in the aetiology of overdose (Brescher, 1972, Monforte, 1977, Manning and Ingraham, 1983, Fugelstad, 1994, Darke and Zador, 1996, Zador et al., 1996). These authors raise three major points. First, that morphine levels in fatal overdose cases have been skewed towards the lower end of the range, with large proportions of cases having morphine concentrations below toxic levels (Monforte, 1977, Kintz et al., 1989, Fugelstad, 1994, Zador et al., 1996). If highly pure heroin was the major or sole cause of death, one would expect to find relatively high blood levels of morphine at autopsy in persons whose tolerance had not diminished. In fact, morphine concentrations in fatalities overlap those detected in heroin users who died of causes other than overdose (Monforte, 1977) or in living heroin users (Aderjan et al., 1995, Darke et al., 1997).

Second, the `typical' overdose victim is an older, dependent user, presumably with a high tolerance for opioids (Ruttenber and Luke, 1984, Oppenheimer et al., 1994, Zador et al., 1996, Aderjan et al., 1995). Finally, the concomitant use of heroin with the central nervous system (CNS) depressants alcohol (Ruttenber and Luke, 1984, Ruttenber et al., 1990, Levine et al., 1995, Zador et al., 1996), and benzodiazepines (Sanchez et al., 1995, Zador et al., 1996, O'Doherty and Farrington, 1997) is associated with the majority of `heroin' overdoses, focusing attention on aetiological factors other than heroin purity. The presence of alcohol at autopsy has also been related to lower blood morphine concentrations (Ruttenber et al., 1990Zador et al., 1996).

Despite the generally accepted role given to purity fluctuations in causing heroin overdose, little work has been conducted directly relating purity to number of overdose deaths. The only study known to the authors in which this was attempted was reported by Ruttenber and Luke (1984). In regression analysis, heroin concentration accounted for 24% of the variance in heroin overdose fatalities that occurred in the District of Columbia between 1979 and 1982.

The current study builds on an earlier study conducted by Weatherburn and Lind (1997), in which street heroin seizures in south western Sydney (SWS) were analysed for purity over a 2 year period. This region has, in recent years, become the major distribution point for heroin in Sydney (heroin used in Australia is of south east Asian origin). The average heroin purity of these samples was 59%. There was a great deal of variation in the purity of samples, with samples ranging from 13 to 80%.

The existence of a heroin purity time series over a 2 year period provided a basis for analysing the relationship between fluctuations in purity and fatal heroin overdoses in the same region. The current study specifically examined the relationship between variations in heroin purity and fatal overdoses in the SWS region for the two year period February 1993 to January 1995. It involved cross correlating time series data on these two variables over the same period.

Section snippets

Heroin samples

The methodology for obtaining heroin samples is described in full by Weatherburn and Lind (1997). Briefly, samples were collected over a 2 year period, from February 1993 to January 1995 in the Sydney suburb of Cabramatta, located in the South Western Sydney Area Health Service region. Cabramatta has in recent years become the major distribution point for heroin in the Sydney region. The samples were obtained as undercover purchases made by police officers from Cabramatta Patrol, or were

Heroin purity

As reported in Weatherburn and Lind (1997), the mean heroin purity of samples collected over the study period was 58.7% (S.D. 14.8, range 13.2–79.8%). The mean purity of samples collected for each fortnight are shown in Fig. 1. The highest mean purity for any fortnight period was 73.5% and the lowest was 19.8%. Highest heroin purity for fortnightly periods ranged from 22.7% to 79.8%.

Heroin-related fatalities

The mean age of the 61 fatal overdose cases was 29.2 years (S.D. 6.8, range 16–50), with 87% male. The number of

Discussion

The major finding from this study was the existence of a moderate correlation between heroin purity and contemporaneous overdose fatalities. Variations in mean and highest heroin purity accounted for 32 and 25%, respectively of the variance in overdose fatalities occurring in the same period. These results are similar to those reported by Ruttenber and Luke (1984), in which purity accounted for a quarter of the variance in overdose fatalities. Similarly, the range of the purity of samples

Acknowledgements

The authors wish to thank the staff at the Westmead Coroners Court, Glebe Coroners Court, Campbelltown Court and Moss Vale Court.

References (24)

  • S. Darke et al.

    A comparison of blood toxicology of heroin-related deaths and current heroin users in Sydney Australia

    Drug Alc. Depend.

    (1997)
  • W. Hall et al.

    Trends in opiate overdose deaths in Australia, 1997–1995

    Drug Alcohol Depend.

    (1998)
  • R. Aderjan et al.

    Morphine and morphine glucuronides in serum of heroin consumers and in heroin-related deaths determined by HPLC with native fluorescence detection

    J. Anal. Tox.

    (1995)
  • Brescher, E.M., 1972. The `heroin overdose' mystery and other hazards of addiction. In: Brescher, E.M. (ed.), Licit and...
  • D. Cottrell et al.

    British opiate addicts: an 11-year follow-up

    Br. J. Psych.

    (1985)
  • S. Darke et al.

    Fatal heroin overdose: A review

    Addiction

    (1996)
  • S. Darke et al.

    Overdose among heroin users in Sydney, Australia I. Prevalence and correlates of non-fatal overdose

    Addiction

    (1996)
  • L. De la Fuente et al.

    The impact of drug-related deaths on mortality among young adults

    Am. J. Pub. Health.

    (1995)
  • English, D.R, Holman, C.D.J., Milne, E., Winter, M.G., Hulse, G.K., Codde, J.P., et al., 1995. The Quantification of...
  • M. Frischer et al.

    Mortality and survival among a cohort of drug injectors in Glasgow, 1982–1994

    Addiction

    (1997)
  • Fugelstad, A., 1994. Heroin deaths in Stockholm, 1986–1991. Paper presented to the Fifth International Conference on...
  • P. Kintz et al.

    Toxicological data after heroin overdose

    Hum. Tox.

    (1989)
  • Cited by (107)

    • Aging out of the federal dependent coverage mandate and purchases of prescription drugs with high rates of misuse

      2021, Economics and Human Biology
      Citation Excerpt :

      Nonmedical users may substitute to purchasing drugs in the black market since a loss of insurance coverage decreases the relative price of illicit substitutes, but moral hazard theory suggests nonmedical users could reduce or stop their drug consumption since the cost of addiction is higher without insurance. Substitution to illicit drugs can lead to additional health problems since illicit drug quality is often unknown and impurities are associated with an increased likelihood of non-fatal overdose and death (Darke et al., 1999).12 I use data from the public-use 2010–2018 MEPS, excluding data before October 2010 since the FDCM did not go into effect until September 2010.

    • The epidemiology of the opioid overdose epidemic in the United States

      2020, The Opioid Epidemic and Infectious Diseases
    View all citing articles on Scopus
    View full text