Illicit drug abuse research is advanced internationally. However, in Finland there has been more extensive research on alcohol abuse than illicit drug abuse. This is because “alcohol use and related problems have traditionally been far more common than drug use and related problems” (Varjonen et al. 2014, pg. 26). Clients in contact with drug abuse treatment services provide useful data to undertake epidemiological research studies among Finnish illicit drug users. Their anonymised health records offer good quality data and relatively large cohort which can be followed longitudinally to answer relevant research questions without huge financial costs to the researchers and without breaching clients’ privacy.
Death is the most serious negative health outcome among illicit drug users. Robust epidemiological studies on mortality among illicit drug users in Finland are scarce. The few existing local studies are limited in various ways. Vuori et al. (2003) investigated deaths in four persons following the ingestion of MDMA and moclobemide but their study was limited by extremely small sample size. Other existing local mortality studies were limited by their focus on narrow subgroups such as drugged drivers (Karjalainen et
al. 2010), toxicological cases of overdose (Simonsen et al. 2011; Salasuo et al. 2009; Vuori et al. 2012), pregnant women (Kahila et al. 2010), and users of prescription medication such as buprenorphine (Häkkinen et al. 2012; Uosukainen et al. 2013a).
At international level, many studies have investigated deaths among illicit drug users, especially using treatment-seeking samples, and they have generated mortality estimates for different types of drugs (Arendt et al. 2011; Calabria et al. 2010; Degenhardt et al.
2011b; Singleton et al. 2009). However, multiple drug use is rampant among treatment-seeking population who are often heavy drug users, and it is likely that the different drugs acted in synergy to produce the health harm leading to death. To address this limitation, it will be more appropriate to generate a single mortality estimate for the combined drug users.
Deaths among illicit drug users are problematic to the society when they occur at young age because such deaths are premature and the society loses its potential workforce. Most of the existing studies have described mortality using traditional mortality indicators (death counts, CMRs, and SMRs), without considering the age at which the deaths occurred. Only very few international studies, for example, Smyth et al. 2007 and Degenhardt et al. 2014, have explored the prematurity of deaths that occur among drug users in terms of PYLL.
The route of drug administration influences the health risks associated with drug use.
Mortality among injectors has continued to receive research attention. Only very few studies have reported mortality among persons who snorted, smoked or orally ingested their drugs, in addition to injectors (Darke & Ross 2000; Thiblin et al. 2004; Quan et al.
2007). Of these, none of them tested the association between the various routes of drug administration and all-cause deaths.
Mortality-related publications showing the causes of deaths from longitudinal cohort studies involving drug users in contact with drug treatment services during the last 10 years have been summarised in Table 1.
22 Table 1. Causes of deaths from longitudinal cohort studies involving drug users in contact with drug treatment services during the last 10 years Author/year Country Sample description PeriodNumber dead SMR¶Specific causes of deaths Ravndal et al. (2015) Norway481 drug users admitted into outpatient and inpatient treatment programmes in Oslo.
1998-2009 74 NR Overdose (n=50), violent deaths (n=11), (including traffic accidents, drowning, suicide, homicide, etc.), HIV (n=2), hepatitis C (n=1), unknown cause (n=6). Pierce et al. (2015) UK198247 opioid users in contact with drug treatment and criminal justice sources in England.
2005-2009 3974 5.7Drug-related poisoning/overdose (n=1715), respiratory disease (n=259), circulatory system disease (n=418), liver disease (n=345), suicide (n=199), homicide (n=77), HIV (n=31), viral hepatitis (n=82). Degenhardt et al. (2014) Australia 43789 drug users registered for opioid substitution therapy in New South Wales.
1985-2005 3685 6.5Accidental drug-related deaths (n=1738), unintentional injuries (n=975), suicide (n=484), liver-related (n=254), cardiovascular disease (n=206), cancer (n=212). Fugelstad et al. (2014) Sweden1640 hospitalised drug users in Stockholm. 1985-2007 630 16.1Heroin intoxication/overdose (n=227), HIV-related (n=92), malignant tumour (n=33), cardiovascular diseases (n=55), gastrointestinal diseases (n=30), suicide (n=39), self-inflicted deaths with undetermined intent (n=60). Table 1 to be continued
23 Table 1 continued Author/year Country Sample description PeriodNumber dead SMR¶Specific causes of deaths Lee et al. (2013) Taiwan10842 heroin users attending methadone maintenance treatment in Taiwan.
2006-2008 256 7.5Somatic causes (n=112), suicide (n=67), HIV (n=10), homicide (n=3). Huang & Lee (2013) Taiwan1616 heroin users that attended methadone maintenance treatment.
2006-2008 26 NR Accident (n=8), suicide (n=7), drug overdose (n=6), cardiovascular disease (n=2), liver disease (n=2), unknown cause (n=1). Arendt et al. (2013) Denmark6445 persons entering treatment for cannabis use disorders.
1996-2006 142 4.9Accident (n=60), natural causes/diseases (n=41), suicide (n=21), homicide (n=6), other/unknown (n=14). Rosca et al. (2012) Israel9818 drug users treated or currently in methadone maintenance treatment.
1999-2008 960 12.2Sudden/undefined deaths (n=196), drug overdose related (n=213), cancer (n=96), suicide (n=53), viral hepatitis (n=48), heart disease (n=46), homicide (n=34). Merrall et al. (2012) UK69456 persons in contact with drug abuse treatment services across Scotland.
1996-2006 2590 4.8-6.4Drug-related deaths (n=1383), suicide (n=269), digestive system diseases (n=168), circulatory system diseases (n=127), homicide (n=118), infectious diseases (n=90). Table 1 to be continued
24 Table 1 continued Author/yearCountry Sample description PeriodNumber dead SMR¶Specific causes of deaths Kuo et al. (2011) Taiwan1254 subjects with methamphetamine dependence admitted for detoxification
1990-2007 130 6.02Suicide (n=42), accidents (n=26), accidental overdose (n=4), undetermined unnatural deaths (n=14), cardiovascular disease (n=13), hepatic diseases (n=6), undetermined natural deaths (n=9). Nyhlén et al. (2011)Sweden561 drug users admitted to a detoxification and short-term rehabilitation unit.
1970-2006 204 5.94Drug-related deaths (n=120, including opioid overdoses, stimulant overdoses, and violent deaths), non-drug related deaths (n=84, including cardiovascular disease, liver cancers, and others). Jimenez-Treviño et al. (2011) Spain214 heroin-dependent persons admitted for methadone maintenance treatment.
1980-2009 106 22.51HIV/AIDS (n=21), overdose (n=7), cancer (n=4), cirrhosis (n=3), unknown (n=62). Dias et al. (2011) Brazil 131 crack/cocaine- dependent patients admitted into treatment between 1992 and 1994.
12 years* 27 12.4Homicide (n=16), HIV/AIDS (n=6), overdose (n=3), drowning (n=1), hepatitis B (n=1). Gibson et al. (2011) Australia 2489 heroin dependent persons entering methadone treatment.
1980-2008 478 4.6Drug-induced deaths (n=130), accidental traumatic injury (n=81), liver-related (n=75), cancer (n=60), suicide (n=36), cardiovascular (n=35). Table 1 to be continued
25 Table 1 continued Author/yearCountry Sample description PeriodNumber dead SMR¶Specific causes of deaths Darke et al. (2011) Australia 615 heroin users enrolled in the Australian Treatment Outcome study (ATOS)
2001-2009 31 4.56Overdose (n=19), disease (n=7), suicide (n=2), unknown causes (n=3). Zábranský et al. (2011) Czech Republic151 injecting drug users in Prague 1996-2010 8 14.4Overdose (n=6), violent accidents (n=2). Stenbacka et al. (2010) Sweden1705 substance abusers in healthcare and other different institutions.
1967-2003 860 3.4Cardiovascular (n=132), accidents (n=127, including transport accidents, falls, homicide/assault), tumors (n=109), definite suicide (n=90), liver cirrhosis (n=90), undetermined suicide (n=60). Ravndal & Amundsen (2010)
Norway276 drug users who had been admitted to inpatient facilities. 1998-2006 36 NR Overdose (n=24 deaths), violent deaths (n=7, including traffic accidents), unknown causes (n=5). Beynon et al. (2010a) UKDrug users within structured drug treatment in North West region of England.
2003-2008 504 NR <40 years at death: 125 drug-related deaths, and 150 non-drug-related deaths. ≥40 years at death: 51 drug-related deaths and 175 non-drug-related deaths. Solomon et al. (2009)
India1158 participants in the Madras Injection Drug Users and AIDS Cohort Study (MIDACS) in Chennai.
2005-2008 85 11.1Overdose (n=22), AIDS (n=14), Tuberculosis (n=8), chronic disease (n=6), accidents (n=5), suicide (n=4).
26 Table 1 continued Author/yearCountry Sample description PeriodNumber dead SMR¶Specific causes of deaths Clausen et al. (2009) Norway3789 opiate dependent people in opioid maintenance treatment in Norway
1997-2003 213 5.0-26.0Drug overdose (n=113), 66 deaths from somatic causes [including AIDS (n=17), liver failure (n=13), cardiovascular disorders (n=8), pneumonia (n=5)], and 29 deaths from traumatic causes [including accidents (n=14), suicide (n=10), homicide (n=5)]. Bjornaas et al. (2008) Norway185 opioid users treated in all medical departments in Oslo. 1980-2000 70 23.6Accidents (n=8), suicide (n=5), cancer (n=3), cardiovascular disease (n=2 deaths), other violent deaths (n=2), other diseases (n=50 deaths). Pavarin (2008) Italy347 cocaine addicts enrolled in treatment 1989-2004 7 4.75Cardiovascular diseases (n=3), injuries and poisoning (n=2), AIDS (n=1), drug overdose (n=1). Gibson et al. (2008) Australia 405 heroin-dependent persons attending methadone and buprenorphine maintenance treatments.
1996-2006 30 NR Drug overdose (n=12), trauma (n=6), cancer (n=2), AIDS-related (n=2), other medical conditions (n=3, including hepatic encephalopathy, endocarditis), unknown causes (n=5). Bloor et al. (2008) UK1033 drug users from 33 drug treatment facilities across Scotland.
2001-2005 38 12.44Drug-related deaths (n=22), suicides (n=6), infections (n=4), assault (n=2), overdose with unclear intent (n=1), alcoholic liver disease (n=1), hypothermia/exposure (n=1), unknown cause (n=1).
27 Table 1 continued Author/yearCountry Sample Period Number dead SMR¶Specific causes of deaths Ødegård et al. (2007) Norway501 drug abusers admitted to treatment at the State Clinic for Drug Addicts.
1981-2003 189 23.4Overdose (n=88), suicide (n=20), AIDS (n=19), accident (n=14), liver disease (n=10), neoplasm (n=6), unknown causes (n=14). Quan et al. (2007) Thailand821 drug users (346 injectors and 475 non-injectors) admitted for detoxification treatment.
1999-2002 33 4.4-13.9IDUs: of the 22 deaths, the main causes included overdose (n=5), septicaemia (n=5), and pneumonia (n=3). Non-IDUs: of the 11 deaths, the main causes were motor vehicle accidents (n=3), and suicide (n=3). Manfredi et al. (2006) Italy1214 intravenous drug users attending a specialised outpatient treatment service in Bologna.
1977-2002 271 NR AIDS (n=143), heroin overdose (n=60), liver cirrhosis (n=17), road accidents (n=20), suicide (n=8), infectious endocarditis and other heart disorders (n=6), neoplasm (n=5), homicide (n=3), pneumonia (n=2). Ribeiro et al. (2006) Brazil 131 patients admitted for treatment at a public alcohol and drugs detoxification unit in São Paulo.
5 years* 23 7.6Homicide (n=13), AIDS (n=6), overdose (n=2), drowning (n=1), hepatits B (n=1). Rehm et al. (2005) Switzerland6281 drug users who participated in heron-assisted treatment in Switzerland 1994-2000 49 9.7AIDS (n=17), accidents (n=9), suicide (n=8), other infections (n=5), cardiovascular disease (n=4), cancer (n=2) Table 1 to be continued
28 Table 1 continued Author/year Country Sample description PeriodNumber dead SMR¶Specific causes of deaths Maxwell et al. (2005) USA13264 patients in methadone treatment programmes1994-2002 766 NR Liver diseases (n=156), cardiovascular diseases (n=138), drug overdose (n=106), unknown (n=62), cancer (n=51), motor vehicle accident (n=46), respiratory disease (n=43), suicide (n=36), AIDS (n=33), homicide (n=31). Bartu et al. (2004) Australia 4280 opiate and amphetamine users admitted for treatment in Perth.
1985-1998 253 NR Drug-related deaths (n=117), suicides (n=34), other diseases (n=54), HIV (n=11), cardiovascular disease (n=9), accidents (n=9). SMR – standardised mortality ratio. NR – not reported. ¶All-cause SMR. *Exact period not stated. Some papers were excluded from the table if authors did not provide specific causes of deaths, if authors did not respond to request for full-text, if the papers were coronial/toxicological reports, if publication date was outside the time frame, if the study was based on different populations such as non-treatment samples, prisoners, etc.
3 Aims of the study
The purpose of this study was to assess deaths that occurred among treatment-seeking illicit drug users during 1997–2010 time periods. The specific research objectives were:
1. To examine the socio-demographic characteristics and drug abuse patterns of the clients at baseline (I).
2. To assess all-cause and specific causes of deaths during the follow-up period (II).
3. To evaluate the prematurity of deaths in the cohort in terms of potential years of life lost before 70 years (III).
4. To examine the association between the route of drug administration and all-cause deaths (IV).