Fatal poisoning among patients with drug addiction

Despite national initiatives such as treatment programmes and heroin clinics, the number of drug addicts in Denmark remains at a high level. In 2010 the number of drug addicts in Denmark was estimated to 33,000, of whom 11,000 abused only cannabis [1]. It was estimated that 13,000 (40%) of the drug addicts injected their drugs [1].

Since 1991 the number of fatal poisonings among drug addicts in Denmark has remained stable at approximately 200 annual deaths [2-4]. However, through the years the abuse pattern has changed and the prescribed opioid, methadone has widely replaced heroin as the main cause of death in Denmark [2-4]. This trend has also been observed in the rest of Europe where abuse of medicinal opioids (methadone, buprenorphine, fentanyl, etc.) has increased, while the abuse of heroin has diminished [5].

This paper present a follow-up study on fatal poisonings among drug addicts in Denmark in 2012. The data will be compared between the different parts of the country as well as with similar studies from 1991, 1997, 2002 and 2007 [2-4, 6]. As in the former studies, the 2012 data were included in a common Nordic study on fatal poisonings among drug addicts [7].

METHODS

This study included all fatal poisonings among drug addicts examined at the three institutes of forensic medicine in Denmark: Copenhagen (Zealand, surrounding
islands, and Bornholm), Aarhus (Jutland, excluding Southern Jutland) and Odense (Funen, surrounding islands and Southern Jutland) in 2012. A drug addict was defined as “a person who, according to information from the police and/or autopsy report, is known to have abused drugs intravenously and/or abused drugs listed in the Single Convention on Narcotic Drugs 1961, Schedule I (heroin, morphine, ketobemidone, cocaine, etc.) and/or the International Convention on Psychotropic Substances 1971, Schedules I and II (amphetamine, LSD, etc.)”.

Data on sex, number of fatal poisonings, age, main intoxicants and other drugs detected in the blood were recorded. Fatal poisonings caused by two or more drugs were recorded according to the drug considered to be the main intoxicant. Heroin is rapidly metabolised to 6-monoacetyl-morphine and further to morphine. Thus, in this study, heroin/morphine is stated in cases where morphine was detected. The toxicological evaluations of the detected drug concentrations were performed according to the experience at the participating institutes [8, 9] and in line with reports from the literature [10-13].

Trial registration: not relevant.

RESULTS

Cause of fatal intoxication

Fatal poisoning was the main cause of death in 90% of all registered deceased drug addicts in Denmark. A total of 188 fatal poisonings among drug addicts were examined at the three institutes of forensic medicine in Denmark in 2012 (Table 1). The frequency of fatal poisoning in the capital and suburbs was 33% and remained unchanged compared with 2007 [4]. The gradual decrease in the frequency of fatal poisoning in the capital and suburbs observed from 1991 (53%) to 2007 (31%) seems to have stopped [4]. Women constituted 23% of the deaths. The age distribution showed a maximum in the 45-49-year age group (see Figure 1 for methadone deaths) (the median age was 41.5 years and the age range was 17-62 years). The median age has increased compared with 2007 (median: 37.5 years). The main intoxicant is listed in Table 2. Opioids were the dominant cause of death (87%) in 2012 as in previous studies conducted since 1991. Methadone was the main intoxicant in 2012 (59%) as in 2007 (51%), and the increase in methadone deaths observed since 2002 (41%) continued in 2012. The frequency of heroin/morphine intoxications showed a corresponding decrease in the same period from 71% in 1997 to 44% in 2002 and 27% in 2012 (Table 2). This trend was observed in the eastern and western parts of Denmark. However, in the area covered by Odense, the frequency of heroin/morphine deaths increased, and the frequency of methadone death decreased from 2007 to 2012 (Table 3). The frequency of methadone deaths (75%) was highest in the area covered by the institute in Copenhagen of which nearly half (47%) were recorded in the capital of Copenhagen (Table 3). At time of death, 52 of the drug addicts (28%) were in substitution treatment with methadone. This seems to be slightly higher than in earlier studies (17-23%) [4]. This should be considered a minimum number as information about methadone treatment was not available for all deaths. Methadone was the main intoxicant in nearly all (92%) of the drug addicts receiving methadone treatment.

Eight deaths were caused by central stimulants, amphetamine, 3,4-methylenedioxy-N-methamphetamine (MDMA/ecstasy) and cocaine (Table 2). This is a slight decrease compared with 2007. Furthermore, there was one death from gammahydroxybutyric acid (GHB).

Prescribed medicine other than methadone caused fatal intoxication in 16 (8.5%) of the drug addicts. The following medicinal drugs caused one death each: tramadol, ketobemidone, codeine, zolpidem, metformine and acetylsalicylic acid. Two deaths were caused by a combination of chlordiazepoxide and ethanol. Antidepressants and antipsychotics were the main cause of death in eight (4%) of the deceased drug addicts.

Two or more drugs were judged to have contributed significantly to 32% of the fatal poisonings of drug addicts in 2012. Multi-poisonings were most often (55%) caused by an opioid in combination with a benzodiazepine and/or alcohol.

Abuse pattern

Table 4 presents all analytical findings in the poisoned drug addicts in 2012. On average, five drugs (median: four) excluding ethanol were detected per case. Ethanol was detected in 36% of the cases and ethanol was above 0.5 mg/g in half of the ethanol-positive cases.

As in 2007, methadone was the most frequently found drug and was detected in 134 (71%) cases [4]. This is an increase compared with previous studies, 2007 (61%), 2002 (33%) and 1997 (31%) [2-4]. Heroin/morphine was detected in 57 (30%) cases and remains among the most frequently found drugs even though there has been a continuing decrease compared with previous years, 2007 (40%), 2002 (48%) and 1997 (71%) [4]. Large regional differences were observed. Methadone was more frequent in the area covered by Copenhagen (84%) than in the areas covered by Aarhus (65%) and Odense (42%). Moreover heroin/morphine was more frequent in the area covered by Odense (55%) than in the area covered by Aarhus (33%) and Copenhagen (21%).

Other opioids, codeine (9%), tramadol (6%), buprenorhine (4%), ketobemidone (4%) and oxycodone (3%) appeared in a limited number of cases (Table 4). Except for an increase in buprenorphine-positive cases, there was no change compared with earlier years [2-4].

Cocaine was detected in 36 (19%) cases. This is a slight increase compared with previous years 1997-2007 (14-15 %) [2-4]. The frequency of amphetamine (10%) has not changed during the past ten years [2-4]. In the area covered by Copenhagen, 26% of the cases tested positive for cocaine. This is much higher than in Aarhus (14%) and Odense (6%). On the contrary, amphetamine appeared more frequently in Aarhus (17%) than in Odense (10%) and Copenhagen (6%). Similar to previous studies in 2007 and 2002, only few cases tested positive for new psychotropic drugs (NPS) (MDMA, methylenedioxypyrovalerone (MDPV) and para-methoxy-N-methylamphetamine (PMMA)). These NPS drugs were only detected in the area covered by Copenhagen.

Diazepam (35%) and tetrahydrocannabinol (34%) were the second most frequently detected drugs. In fact, benzodiazepines (71%) as a group occurred as frequently as methadone (Table 4). Methylphenidate (5%), pregabalin (5%) and GHB (1.6%) appeared for the first time and were only detected in the areas covered by the institutes in Copenhagen and Aarhus.

Cases with one or more antidepressants/antipsychotics increased from 25% in 2007 to 41% in 2012, and antidepressants/antipsychotics as a group were more frequent than heroin/morphine [4]. The frequency of antidepressants/antipsychotics was similar in all parts of Denmark.

DISCUSSION

As from 2009, the so-called hard-to-treat heroin abusers in Denmark have been eligible to receive prescribed heroin for injection at special heroin clinics [1]. Five heroin clinics existed nation-wide (Copenhagen, Aarhus, Odense, Hvidovre and Esbjerg) at the end of 2012. In total, 252 drug addicts have received heroin in these clinics from 2009 to 2012 [1]. Nearly 30% have left the treatment and most returned to substitution treatment [1]. The decrease in heroin/morphine deaths from 2007 to 2012 seems to be a continuing decrease initially observed in 2002, and any positive influence from the heroin clinics is uncertain. In Odense, the number of heroin/morphine deaths was unchanged from 2007 to 2012. Over the years, the number of fatal poisonings remained unchanged as the decrease in heroin/morphine deaths has been replaced by a corresponding increase in methadone deaths. This trend, by which medicinal opioids have replaced heroin as the leading cause of death, has also been observed in the other Nordic countries and in rest of Europe and in the USA [5, 7, 14]. While methadone mostly replaced heroin as cause of death in Denmark, fatal poisonings from other opioids like buprenorphine and fentanyl increased markedly in Sweden and Finland in 2012 [7].

Both methadone and buprenorphine are used for substitution treatment of opioid dependence in Denmark. In 2011 about 6,200 drug addicts were in methadone treatment and 1,400 were in buprenorphine
treatment [1]. The increase in methadone deaths is undoubtedly connected to the high number of clients in methadone treatment. This is supported by the fact that among the deceased addicts reported to be in methadone treatment, 92% died from a methadone overdose in 2012. On the other hand, the increase in median age indicates that treatment programmes also save lives. Substitution treatment of drug addicts has been found to be less restrictive in Copenhagen than in Odense and Aarhus [15]. Many drug addicts were not supervised while taking methadone in Copenhagen [15]. This could be the reason for the high number of methadone deaths in this area.

Buprenorphine deaths did not occur in Denmark in 2012, and there was only one buprenorphine death in 2007 [4]. Conversely, the development in buprenorphine deaths has been overwhelming in both Finland and Sweden. In 2012, 42 and 35 buprenorphine deaths were recorded in Finland and Sweden, respectively [7]. Suboxone – containing buprenorphine in combination with the opioid antagonist naloxone – is used for treatment of opioid dependence. The single buprenorphine death in Denmark was ascribed to this combination. Suboxone has long been used for treatment of drug addicts in Finland, and many deaths have occurred due to use of Suboxone [16]. Buprenorphine deaths in Finland are exclusively multi-poisonings, primary with benzodiazepines and alcohol [17]. As benzodiazepine and/or alcohol contributed to more than half of the multi-poisonings in Denmark in 2012, side abuse should be taken seriously.

As previously, central stimulants (cocaine, amphetamine and MDMA) caused few deaths. The number of deaths from central stimulants was even lower in 2012 (n = 8) than in 2007 (n = 13) despite an increase in cocaine-positive findings [4]. More deaths from amphetamine and cocaine were to be expected due to a marked increase in non-fatal intoxications from amphetamine and cocaine from 2004 (n ≈ 125) to 2012 (n = 424) recorded by the hospitals in Denmark [1]. Countries like Spain and the United Kingdom have experienced a three-fold increase from 2000 to 2008 in the number of cocaine-intoxicated people admitted to hospitals [18]. Even so, cocaine deaths were rare in these countries [18].

Poly-drug use was widespread in all parts of the country. Opioids, cocaine, amphetamine, cannabis, benzodiazepines and alcohol were included in the abuse. The considerable regional differences in drug findings in this study were in agreement with the pattern of street drugs in Denmark reported in 2012 [19]. In that study, heroin was more frequently seized in the police districts of Odense and Esbjerg than in the police districts of Copenhagen, Aarhus and Aalborg [19]. Cocaine was more frequently seized in the Copenhagen police district, whereas amphetamine appeared more frequently in the western part of Denmark [19]. Heroin seems to play a smaller part in the abuse indicated by the decrease in heroin/morphine intoxications. Amphetamine and cocaine were seized 3-4 times more frequently than heroin in Denmark in 2012 [20]. But, still, 30% of the drug addicts tested positive for heroin/morphine.

Although the number of new NPS drugs has increased immensely in Europe [5], NPS drugs were seldom detected in the drug addicts.

The frequent use of antidepressants and antipsychotics seen in all parts of Denmark was also observed in the other Nordic countries [7]. Even deaths from these medicinal drugs occurred. This indicates that a large number of drug addicts also have psychiatric illness. Treatment of such co-morbidity is highly recommended.

CONCLUSIONS

The number of fatal poisonings remains at a high level and has stabilised at approximately 200 annual deaths. Methadone was the main intoxicant. The decrease in heroin/morphine deaths, initially observed in 2002, continued and was, as in previous years, accompanied by an increase in methadone deaths. There seems to be a connection between the increase in methadone deaths and methadone treatment. Nevertheless, substitution treatment also saves lives. Large regional differences in abuse patterns were demonstrated. Methadone was more frequent in the areas covered by Copenhagen and Aarhus, whereas heroin was most frequent in the area covered by Odense. Cocaine was most frequent in the eastern part of Denmark, whereas amphetamine was more frequent in western part of the country. Use of antidepressants and antipsychotics increased to a high level, indicating that a large number of drug addicts also have psychiatric illness. As the drug market is changing and different initiatives from the authorities influence the drug situation, further studies in this area are recommended.

Correspondence: Kirsten Wiese Simonsen. E-mail: kirsten.wiese@sund.ku.dk

Accepted: 4 August 2015

Conflicts of interest:Disclosure forms provided by the authors are available with the full text of this article at www.danmedj.dk