Association between availability of heroin and methadone and fatal poisoning in England and Wales 1993-2004.

BACKGROUND The UK heroin market is the biggest in Europe and approximately 70% of heroin deaths are due to fatal poisoning. Methadone treatment for heroin addiction in the UK, the 'British system', is unique as it is largely provided by General Practitioners. METHODS The Office for National Statistics provided data on deaths, the Home Office provided law enforcement data on drug seizures and the Department of Health data on prescriptions. For methadone treatment we calculated the death rate per 1000 patient years. We used Spearman's rank correlation to assess the association between illicit drug seizures for heroin and methadone and deaths. RESULTS Between 1993 and 2004 there were 7072 deaths involving heroin/morphine (86% males) and 3298 deaths involving methadone (83% male). From 1993-1997, directly age-standardized mortality rates for males were similar for both drugs, increasing from approximately 5 to 15 per million. Mortality rates for heroin continued to increase until 2000, subsequently decreasing from 30 to 20 per million by 2003, and rising again to 24 per million in 2004. In contrast, mortality rates for methadone decreased between 1997 and 2004 to just above 1993 levels. Among females the mortality rate for both drugs was lower than for males throughout the study period, remaining relatively stable. Methadone deaths per 1000 patient years remained similar between 1993 and 1997, after which they fell by three quarters. For both heroin/morphine and methadone, deaths were strongly associated with seizures (Spearmans' coefficient for males: heroin, P = 0.95, P < 0.001 and methadone, P = 0.83, P = 0.0013). CONCLUSIONS Our study suggests the 'British System' can deliver substantial expansion of treatment without increased mortality risk. The fall in heroin/morphine deaths since 2000 may also be an indication of success of increasing methadone treatment. Data on mortality risk is needed to determine whether increased methadone treatment has reduced drug-related deaths.