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Characteristics of fatal methadone overdose in Manchester, 1985-94

^a Department of Histopathology, Clinical Sciences Building, Manchester Royal Infirmary, Manchester, M13 9WL, ^b Department of Pathological Sciences, University of Manchester, Manchester, M13 9PT

Correspondence to: Dr Benbow.

Deaths associated with methadone, a drug often prescribed for opiate addiction, are increasing.^{1 2 3} We describe the recent experience in Manchester, particularly in relation to diverted methadone (methadone taken by someone other than the person to whom it was prescribed).

Subjects, methods, and results

We examined the records of the coroner for the City of Manchester (population around 400 000) from January 1985 to December 1994 and identified all fatal overdoses. Of 602 deaths associated with drug and alcohol toxicity, 90 were attributed wholly or partly to methadone. Another person died after developing gangrene of the arm from intravenous methadone injection. In 52 of the 90 cases methadone was the sole cause of death, the remaining deaths being caused by methadone combined with other drugs or alcohol, or both. Victims' ages ranged from 2 to 50 years (mean 26.3 years; interquartile range 22 to 31 years); 79 were male. Eighteen of the victims were resident outside the city but died within its boundaries; the remainder had Manchester addresses, including one who died in Amsterdam but whose body was returned to Manchester for necropsy. Verdicts at inquest were misadventure (57), open (21), suicide (6), and accidental (1). Five inquests (on four children, aged 2 or 3 years, and one adult) were adjourned for criminal proceedings. Charges were brought in four, manslaughter being proved in two. In the remaining case the inquest was reopened and a verdict of unlawful killing recorded.

Evidence at inquest showed that 36 of the victims had taken methadone that had been prescribed to them; 32 had taken methadone prescribed to others (diversion), including four who bought methadone. In the remaining 22 cases the source was not recorded. The coroner usually records the prescription of methadone, so these cases probably also represent diversion of the drug.

Deaths associated with methadone rose steadily during the study, roughly in parallel with the rise in methadone prescription. In 1994 methadone accounted for 30.6% of all fatal overdoses in Manchester, and methadone associated deaths in Manchester accounted for 18.8% of the total in England and Wales in 1991 (table 1).

Table 1--Details of fatal methadone overdoses in Manchester, 1985-94. Values are numbers of overdoses unless
stated otherwise
------------------------------------------------------------------------------------------------------------
Variable                                   1985   1986 1987 1988 1989 1990 1991 1992 1993 1994 Total
------------------------------------------------------------------------------------------------------------
Fatal overdose:
  All methadone related                       0      0    4    4    2    11   12   15   20   22    90
  Methadone alone                             0      0    1    2    0     6    9    6   14   14    52
  Other substances only                      46     59   45   53   56    56   61   39   47   50   512
Deaths associated with methadone (% of
 all overdoses in Manchester)                 0      0  8.2  7.0  3.4  16.4 16.4 27.8 29.9 30.6  15.0
Source of methadone:
 Own prescription                             0      0    2    2    1    4    3    7    9    8     36
 Known diversion                              0      0    2    2    1    3    5    5    7    7     32
 Probable diversion                           0      0    0    0    0    4    4    3    4    7     22
Deaths associated with methadone:
 England and Wales*                           9     14   46   32   34   60   64  115   NA   NA
 Manchester (% of total for England
 and Wales)                                   0      0  8.7 12.5  5.9 18.3 18.8 13.0   NA   NA
Opiate users in Manchester+:
 Methadone, alone or in combination          NA     36   31   54   68  141  234  372  320   530
 All opiates                                 NA    503  559  587  628  737  916 1062  935  1141
------------------------------------------------------------------------------------------------------------
NA = not available.
*Data from the Office of Population Censuses and Surveys.4
+University of Manchester Drug Misuse Database (T Millar, personal communication).

Comment

Unexpected, unexplained, and unnatural deaths are reported to the coroner. The victims have a full necropsy, with toxicological examination when no clear cause of death is found. During the study toxicological samples were submitted to one of two laboratories. Until 1985 or 1986 these laboratories estimated urinary methadone concentrations using semiquantitative enzymic methods. Subsequently, they used a fully quantitative immunoassay that can be applied to any fluid or tissue. Broad screens for drugs of misuse are routine, and detection of one misused substance prompts a search for other commonly misused substances. Underascertainment of cases is likely to have been small.

Methadone is used in two main ways in opiate addiction. In the client centred approach drug misusers are weaned off all opiates to cure addiction. In contrast, the public health approach aims at reducing the risk taking behaviour associated with heroin misuse, rendering needle sharing redundant and avoiding the risks of HIV infection and viral hepatitis.⁵ The public health approach has recently been adopted by Manchester Health Commission, but we understand that it was informally adopted several years ago by some of the authorities responsible for managing drug misuse locally. This adoption coincided with the rapid increase in methadone prescription (and associated deaths) that started in 1990. We are concerned that many new clients will be recruited to methadone maintenance programmes. They may themselves be at comparatively low risk of overdose, but diversion of methadone endangers others, including children. Indeed, our findings suggest that diversion accounts for most deaths from methadone. A public health approach to opiate misuse is laudable but should be tempered with caution. We hope that the resources necessary for safer dispensing of methadone will be made available.

We are grateful for the help of many people. Some have asked not to be named, and so we believe that all should remain anonymous.

Funding: None.

Conflict of interest: None.

1. Farrell M, Strang J, Neelman J, Reuter P. Policy on drug misuse in Europe. BMJ 1994;308:609-10. [Free Full Text]
2. Farrell M, Ward J, Mattick R, Hall W, Stimson G, des Jarlais D, et al. Methadone maintenance treatment in opiate dependence: a review. BMJ 1994;309:997-1001. [Free Full Text]
3. Clark JC, Milroy CM, Forrest ARW. Deaths from methadone use. Journal of Clinical and Forensic Science 1995;2:143-4.
4. Office of Population Censuses and Surveys. Mortality statistics--injury and poisoning. London: OPCS, 1987-94. (Nos 11-18, 1985-92.)
5. Caplehorn J. Britain has been overcommitted to psychological theories of drug dependence. BMJ 1995;310:463. [Free Full Text]

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