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| Journal of the New Zealand Medical Association,
12-March-2004, Vol 117 No 1190
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Reduction in crime by drug users on a methadone maintenance
therapy programme in New Zealand
Ian Sheerin, Terri Green, Douglas Sellman, Simon Adamson,
and Daryle Deering
Drug-related crime is a major cost for the
community—incurring insurance, law enforcement, and imprisonment costs,
and also involving loss of property. Reduction in crime and imprisonment has
been used in many studies as a measure of treatment
outcome.1 There is strong evidence from other
Western countries, which shows that high rates of crime are associated with the
injecting of illicit opioids.2,3 Furthermore,
it has been postulated that low rates of employment among IDUs, combined with
the high costs of illicit drugs, result in many IDUs turning to crime as a way
of funding their drug habits.1,4 Reduction in
property crimes have been demonstrated among injecting drug users (IDUs)
retained in methadone maintenance therapy (MMT) in North
America1,3 and
Australia5. In New Zealand, one of the aims of
the national methadone protocol is to reduce crime associated with illegal
opioid use.6
Limited evidence is available on changes in criminal
activity associated with MMT for opioid addiction in New Zealand. It has been
suggested that reductions in the cost of crime and imprisonment in New Zealand
could more than offset the costs of MMT,7 and
that it may help to justify funding of more methadone services to address
waiting lists for MMT. A New Zealand study showed high rates of crime among IDUs
on the waiting list for MMT in Christchurch, but did not investigate changes in
crime after IDUs started MMT.8 A study of IDUs
on MMT in Otago found evidence of reductions in drug-related
convictions,9 but did not provide information
on types of criminal activities or on costs of crime to society.
In New Zealand, there is concern about ethnic differentials,
with Maori (the indigenous people) having lower health status, making up half of
the national prison population, and being over-represented in admissions to
alcohol and drug services.10 In 1998/99, 16% of
admissions to MMT in Christchurch were Maori (Canterbury District Health Board,
personal communication, 1999). However, there is scant information on reduction
of crime for Maori IDUs in MMT.
Resource limitations have resulted in waiting lists for MMT.
Waiting times have been found to vary by
location,11 with a mean waiting time of 12.7
months in Christchurch (research in progress). There has been a gradual increase
in funding for MMT with 3774 patients receiving MMT nationally in
2001.11 However, there has also been opposition
to funding services for drug addiction with a proportion of the community
remaining sceptical about the benefits of
MMT.11 Therefore, in order to inform this
debate and decisions on resource allocation, it is necessary to research the
effects of MMT on changing criminal behaviour and the use of illicit drugs, in
addition to health outcomes in the New Zealand setting. This paper reports the
findings on changes in crime associated with MMT.
MethodsA preliminary survey (hereafter
termed Interview 1) was undertaken of IDUs on MMT in Canterbury with interviews
of approximately 1 hour occurring between September, 1999 and November, 2002.
Eighty-five randomly selected participants who had been prescribed MMT for at
least 3 weeks were recruited (51 non-Maori and 34 Maori) to ensure sufficient
Maori participants to examine ethnic differences. At interview, data was
obtained on demographics, current drug use, history of the costs of drug use,
and criminal activity. A follow-up interview (18 months after Interview 1) was
administered to obtain longitudinal data on outcomes of continued treatment,
drug use, and criminal activity. The study was approved by the Canterbury Ethics
Committee.
At the first interviews (Interview 1), self-reported
data were obtained on drug use and criminal activity during the previous week.
Information on drug use and crime before MMT was also obtained by self-report.
Average illegal earnings before MMT were estimated from self-reported
expenditure on drugs before MMT, less $100 per week, which (it was assumed)
could have been funded from legitimate income. This was calculated as a
conservative estimate of illegal income—given that Adamson and
Sellman,8 in their methadone waiting list
sample, found that average illegal earnings per week exceeded the total value of
drugs used by approximately $200 per week. In addition, illegal earnings were
assumed to be zero if participants reported that they did not commit any crime
before MMT or were supplied free-of-charge by another person.
Costs of losses to society due to criminal activity at
Interview 1 were estimated in two ways. The first method summed the illegal
income from the crimes. The second method used a mixed approach, attributing a
value to goods stolen or received based on the open market value of the goods.
Other crimes (eg, fraud, prostitution, drug dealing) were valued as in the first
method, at the amounts earned by the offender. In neither method was a value
assigned to crimes such as breach of parole, disorderly behaviour, wilful
damage, or firearms offences.
Information on the details of crimes committed before
MMT was not available. Costs of the societal losses of crime before MMT were
estimated using only the first method (ie, by the illegal income of
participants).
Costs of imprisonment were based on information
supplied from the Department of Corrections (2000), which shows an average cost
of $41 462 per prisoner per annum in the year 2000 (averaged over all levels of
security.) The estimated annual cost of imprisonment before MMT is in year-2000
dollars and was calculated by dividing the average cost of imprisonment per
person by the mean number of years since participants started injecting opioids
(15.6 years). This approach provides an estimate of the annual costs of
imprisonment associated with injecting drug use. Because the ethnic differences
were not statistically significant in regard to history of imprisonment and time
since starting injecting, the overall mean values were used for the purposes of
calculating costs of imprisonment.
Data were analysed using ‘Statistical Package for
the Social Sciences’ (SPSS). For statistical tests of significance of
changes (in proportions over time), we used McNemar’s test. T tests were
used to test for differences between mean values.
ResultsThe mean duration of the current
episode of MMT, from stabilising on MMT until Interview 1, was 57 months per
participant (52 months for non-Maori and 64 months for Maori; range 2–276
months). The mean number of years between starting to inject and admission to
MMT was 15.6 years. Fifty-three percent of the participants were men. The mean
age was 35 years for Maori and 36 years for non-Maori. The mean age of starting
to inject opioids was 20 years. No ethnic differences in these variables were
found. Only 31% of participants reported that they had full-time work before MMT
and (at Interview 1) most were on welfare benefits (38% on sickness benefits and
20% on invalids’ benefits). Participation in full-time employment reduced
from 31% before MMT to 12% at both Interview 1 and at follow-up (significant, p
<0.01). During this period, participants who said they were unemployed or on
welfare benefits increased from 45% before MMT to 64% at Interview 1
(significant, p <0.05).
There was evidence of widespread criminal activity before
participants started MMT. Eighty-nine percent reported that they had criminal
convictions, and 61% reported having convictions for crimes that were committed
to earn money for drugs. For those with convictions, the mean number of
convictions related to drugs and alcohol was 24. Fifty-five percent had a
history of imprisonment. For those who had been in prison, the mean total weeks
of imprisonment was 108.3, which was spread over a mean of 17 years since these
participants were aged 16. The mean number of prison sentences was 3.5. There
were no significant ethnic differences in these variables. These data indicate
high levels of criminal activity before MMT.
Participants described committing many types of crime before
starting MMT in order to get money to pay for illicit drugs. For women, these
activities include prostitution, drug dealing, and property crime. For men, the
main activities included drug dealing and property crime.
Use of illicit drugs
At Interview 1, participants reported that their use of both opioids and
benzodiazipines had reduced compared with the 6-month period before they started
MMT. All participants reported using opioids (with a mean of 6.8 days per week)
before starting MMT. However, at Interview 1, only 10% of non-Maori and 9% of
Maori reported that they had used opioids during the previous week (p <0.001,
using McNemar’s test); see Table 1.
Table 1. Reductions in opioid use, expenditure on
drugs, illegal income, and crime since starting methadone maintenance therapy
(MMT)
*At Interview 1, participants had been on MMT for a
mean time of 57 months; †significant at p
<0.001; ‡includes possession and
smoking of cannabis, and traffic offences.
Use of illicit benzodiazipines reduced from 48% of IDUs (in
the 6-month period before MMT) to 13% in the previous week at Interview 1 (p
<0.001). However, participants reported a non-significant increase in use of
cannabis with 59% using it before MMT compared with 65% using at Interview 1.
There were no significant ethnic differences in changes in use of these
substances.
Changes in expenditure on drugs can also be viewed as an
indicator of changes in drug use. The reduction in expenditure on illicit drugs
was dramatic and was statistically significant (p <0.001) for both Maori and
non-Maori (Table 1). Non-Maori reported spending a mean of $1144 per week per
person before MMT, which had reduced to $39 per week per person at Interview 1
(p <0.001). Expenditure on drugs by Maori reduced from a mean of $1532 per
week per person before MMT to $62 per person per week at Interview 1 (p
<0.001). The ethnic difference in expenditure on drugs was not statistically
significant. Among all participants, in the 6-month period before starting MMT,
mean expenditure on drugs per week per participant was $1299, which reduced to
$48 at Interview 1 (p <0.001).
There was no significant gender difference in expenditure on
illicit drugs before MMT. The main variable associated with expenditure on drugs
was involvement in crime. Participants who reported criminal offending also
reported significantly higher expenditure on drugs, with a mean of $1441 per
week compared with a mean of $580 per week for people who reported no crime
before MMT (p <0.001).
Illegal income
Before starting MMT, the mean illegal income for all participants was $1162 per
week per person, which reduced to $116 per week per person at Interview 1 (Table
1, significant at p <0.001). There were some non-significant differences by
ethnicity in mean illegal income before MMT. However, there were wide variances
in this population, with estimated illegal income before MMT ranging from $0 to
$6900 per week per person. Hence, we conclude that illegal incomes were similar
for both Maori and non-Maori IDUs and that the reduction in illegal income while
they were on MMT was similar for both groups.
Participants who reported receiving illegal income reduced
dramatically from 86% before MMT to 12% at Interview 1 (p <0.001). This
reduction was similar for both Maori and non-Maori. In most cases, the illegal
income for the week prior to Interview 1was below $400. But there were five
people who reported earning more ($500, $637, $1170, $2500, and $3030
respectively), and they had been on MMT for times ranging from 3 to 12 years.
The two people with the highest illegal earnings had earned their money mainly
from drug dealing. The two women who earned $630 and $1170 made their money
mainly from prostitution.
Level of criminal
activity Eighty percent of non-Maori and 88% of Maori participants
reported that their involvement in crime had reduced considerably since they had
been on MMT. Only 14% of non-Maori and 9% of Maori said their involvement was
unchanged or increased. Over 90% said their involvement with drug dealers or
people committing crimes had reduced.
There was a large reduction in the frequency of crime
reported by participants (Table 1). Eighty-eight percent of participants said
that they had been involved in crime before MMT, compared with 36% in the
previous week at Interview 1 (significant at p <0.001). However, the
reduction in the level of crime is perhaps better illustrated by the finding
that before MMT, 60% said they were committing crime on a daily basis, compared
with only 1% in the previous week at Interview 1 (Table 1, significant at p
<0.001). There were no significant ethnic differences in these
changes.
Reduction in crime is also indicated by the finding that
before MMT, participants spent a mean of 4.9 days per week committing crimes,
compared with 0.7 days per week at Interview 1 (Table 1, p <0.001). There
were no significant ethnic differences.
Arrests The pattern
of arrests since starting MMT is an indicator of the proportion of methadone
patients who continue crime. At Interview 1, 33% of non-Maori and 47% of Maori
reported they had been arrested for crimes committed since starting MMT (42% of
all participants). For those who had been arrested, the mean number of arrests
was 3.2 for both Maori and non-Maori. Only two of these arrests resulted in the
persons being released without charge. All other arrests resulted in
convictions, most commonly with fines and/or periodic detention. There were no
differences evident between Maori and non-Maori in the pattern of convictions.
This pattern of arrests occurred over a mean time of 57 months on MMT, a long
period during which it is possible that the rate of arrests may have
reduced.
At follow-up, 18 months (mean) after Interview 1, 17
participants (20%) said they had been arrested in the previous year. Only one of
these arrests resulted in release without charge. This indicates that a
proportion of IDUs continue criminal activity, even after a mean time of almost
5 years on MMT.
Types of criminal offences
at Interview 1 At Interview 1, the three types of offences that were most
frequently reported by participants were drug dealing (11%), benefit fraud
(13%), and traffic offences (12%) (see Table 2). Five percent of participants
reported either cultivation of cannabis, breach of supervision, or breach of
parole, respectively. Property crimes, such as thefts and receiving stolen
goods, were reported by few people. There were no differences evident between
Maori and non-Maori in the types of offences reported. Excluding traffic
offences and possession of cannabis, 29% of participants reported committing at
least one offence in the week prior to interview. However, 37% of non-Maori and
18% of Maori reported committing at least one offence (Table 2); the difference
by ethnicity was significant at p = 0.05. At Interview 1, most of the people who
reported supplying drugs said they were doing so as a favour to other people (at
little or no financial gain). Two people reported financial gains from dealing
($2500 and $3000 respectively).
Table 2. Types of criminal offences reported by
participants on MMT in the previous week (at Interview 1)
Note: Some
participants said they committed more than one crime. A total of 81 offences
were reported.
*The difference by ethnicity was significant at
chi-square = 3.78, p = 0.05, degrees of freedom = 1
There was a large reduction in involvement in prostitution
for both Maori and non-Maori (p <0.001) For Maori women, 89% said they earned
money from prostitution before MMT, compared with only 6% at Interview 1.
Sixty-eight percent of non-Maori women said they had been involved in
prostitution before MMT, while only 5% remained involved at Interview 1. The
ethnic difference was not statistically significant.
Reduction in costs of
crime Two components of the societal costs of crime can be estimated from
this research—the cost of imprisonment and the cost of losses due to
criminal activity.
Before MMT, average costs of imprisonment across the whole
sample were $3067 per person per year compared with $2073 at Interview 1. The
reduction in cost averaged $994 per participant per year and applied to both
Maori and non-Maori.
Information was not available on the level of offending
according to time on MMT, but the follow-up interviews, at 18 months (mean)
after Interview 1, revealed that six participants had been imprisoned between
Interview 1 and follow-up. This indicates that, in any given year, approximately
5% of these participants will be imprisoned while they are on MMT.
The illegal income of IDUs can be used as an estimate of the
cost to society of losses incurred through theft, fraud, etc. The mean illegal
income per IDU dropped from $1162 per week before MMT to $116 per week at
Interview 1—a reduction of $1046 per week or $54 392 per year (Table 3).
This reduction in societal costs was similar for both Maori and non-Maori. This
is likely to be an underestimate of the reduction since the value to society of
the loss both before MMT and at Interview 1 is likely to be much higher than the
amount of illegal income. For example, the study found that the value to society
of the losses associated with the crime reported at Interview 1 totalled $13 180
for the 81 offences that were identified in the week prior to interview. This is
an average of $155 per IDU per week, compared to the $116 generated in illegal
income.
Table 3. Reduction in costs of crime to society (per
IDU per year)
*This does not
include costs of law enforcement or the judicial system
DiscussionThis study provides data showing
substantial reduction in crime among IDUs who are retained in MMT. High rates of
criminal activity before MMT were followed by reductions in crime after
stabilisation on MMT.
The findings in this study of high crime rates before MMT is
supported by an earlier study of IDUs on the waiting list for MMT in
Christchurch. Adamson and Sellman found that 88% of people on the waiting list
for MMT in Christchurch reported receiving illegal income in the week preceding
interview.8 The main types of illegal activity
they recorded were drug dealing, property crime, and prostitution. Adamson and
Sellman found that 61% reported committing property crimes in the 7 days before
interview (a mean of 8.4 crimes). Seventy-two percent reported drug-related
crimes, including supply and cultivation.
Most people cannot sustain, for any length of time, a drug
habit that costs an average $1299 per week by financing it from normal paid
work. Although, some people reported selling possessions, borrowing, and using
savings to buy drugs, this was usually sustained for only short periods of time
before participants turned to other ways of financing their habits. Research (in
progress) has shown that, before MMT, most participants financed their drug
habits from sources of income other than from normal paid work—notably
from property crime, drug dealing, and prostitution.
Adamson and Sellman found a mean illegal income of $1079 per
week per person among people on the waiting list for
MMT.8 This figure is similar to the mean
estimated illegal income before MMT of $1162 per week for participants in this
sample.
This current study has demonstrated that IDUs being on MMT
in New Zealand is associated with substantial reductions in expenditure on
drugs, crime, and imprisonment. The data indicate that most of these IDUs have
stopped crime since being on MMT. However, approximately 29% continue
significant criminal offending regardless of the length of time on
MMT.
This study indicates reduced societal costs of crime per
participant of $55 386 per year per IDU. However, this estimated reduction in
costs is low, because costs of property crime to victims are higher than the
amount earned illegally by offenders who (for example) sell stolen goods at
lower than market value. Adamson and Sellman8
found that the market value of crime was 2.3 times the amount earned by the
offenders who were IDUs on a waiting list for MMT in Christchurch. Similarly,
studies of crime committed by IDUs in the USA, estimated the legal market value
of stolen goods was three times the illegal income of
IDUs.2,13
By following the methods of Adamson and
Sellman,8 and valuing the losses from crime at
2.3 times the illegal income, the societal cost of the loss due to criminal
activity before MMT is estimated at $2673 per week per IDU. Comparing this with
the $155 per week at Interview 1, an upper estimate of the reduction in societal
costs of losses from criminal activity is $2518 per IDU per week (or $130 936
per annum). Including the cost reduction for imprisonment yields, an upper
estimate of the reduction in societal costs of crime is $131 930 per IDU on
MMT.
Both the lower and upper estimates of costs of crime to
society presented here are conservative since they exclude the costs of law
enforcement and the judicial system. Also, no monetary value has been placed on
losses due to crimes such as assault, offensive behaviour, illegal possession of
firearms, or breach of probation.
We found no major ethnic differences in drug use and crime.
Research (in progress) is finding that there are ethnic differences that are
related to family issues and to employment. However, the large reductions in
illicit drug use and crime were similar for both Maori and non-Maori.
This study had sufficient power to detect moderate-to-large
ethnic differences that may be significant from a clinical point of view.
However, it is possible that a larger sample size may have detected smaller
ethnic differences that may be of interest from a population health viewpoint
(such as in expenditure on illicit drugs before MMT, or in involvement in
prostitution).
Different studies have used different measures of crime,
including official statistics.5 However,
official arrests are not necessarily an accurate indicator of crime because many
offences may go either unreported or unsolved. Self-report is a different method
of measuring crime that may be more sensitive as it includes unreported and
unsolved crimes. There is evidence that under safe and confidential conditions
(as in this study), methadone patients give accurate reports about their drug
use and crime.9
There is evidence from other countries that crime rates are
reduced among IDUs in MMT.1 However, it has
also been found that retention in treatment and patient outcomes vary according
to the practices of different methadone
programmes.1,5 Hence, the findings of this
current research should only be generalised to other settings with
caution.
A potential methodological weakness of this study is that it
relies on participants’ memory recall of their drug use and crime before
they started MMT. However, the validity of these data is supported by a close
similarity to the findings of Adamson and
Sellman.8 Furthermore, the reductions in crime
and illicit opioid use are of such magnitude that pre-MMT drug use and crime
would have to be grossly over-estimated to alter the fundamental conclusion that
significant reductions in societal costs occur following commencement of MMT.
In summary. our results indicate substantial quantifiable
societal benefits of MMT that exceed the costs of MMT (estimated at $4497 per
person per annum.) From a societal standpoint, there is an argument to improve
access to MMT and to reduce waiting lists. These results also raise a resource
allocation issue in so far as the costs of MMT fall on the health budget while
the benefits in terms of reduced crime are accrued in other sectors such as the
justice system, private firms, and households. If such benefits could be
explicitly linked to health-sector funding decisions, the wider societal effects
of improving access to MMT could be included in decisions on the level of
resourcing of MMT programmes.
Author information:
Ian Sheerin, Health Economist and Lecturer, Department of Public Health and
General Practice; Terri Green, Senior Lecturer; Douglas Sellman, Lecturer; Simon
Adamson, Lecturer; and Daryle Deering, Department of Psychological Medicine,
Christchurch School of Medicine and Health Sciences, University of Otago,
Christchurch
Acknowledgements:
This research received funding from the Maori Health Committee of the Health
Research Council and from ALAC. The authors also acknowledge the support of the
participants in this study, the staff of the Alcohol and Drug Service, Alison
Pickering, Naomi Malcolm, Meg Harvey, Roger Wright Centre, Tuari Potiki,
Canterbury District Health Board, and Tahi Takao.
Correspondence: Ian
Sheerin, Department of Public Health and General Practice, Christchurch School
of Medicine and Health Sciences, PO Box 4345, Christchurch. Fax: (03) 364 3614;
email ian.sheerin@chmeds.ac.nz
References:
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