Anne Line Bretteville-Jensen

Addiction and discounting

In 1988, Becker and Murphy [Becker, G.S., Murphy, K.M., 1988. A theory of rational addiction. Journal of Political Economy, 96, 675-700.] launched a theory in which they proposed that the perspective of rational decision-making could be applied also to cases of addictive behaviour. This paper discusses the theorys assumptions of interpersonal variation and stability in time preferences on the basis of estimates derived from three groups of people with different consumption levels of illegal intoxicants. We find that active injectors of heroin and amphetamine have a higher discount rate than a group reporting that they have never used the substances. Of greater interest, though not in accordance with Becker and Murphys assumption of stability, we also find that the discount rate among active and former users differs significantly. These findings raise the question of whether a high time-preference rate leads to addiction or whether the onset of an addiction itself alters peoples inter-temporal equilibrium.

Illicit use of opioid substitution drugs: prevalence, user characteristics, and the association with non-fatal overdoses.

BACKGROUND AND AIMS Diversion of opioid substitution drugs (OSD) is of public concern. This study examined the prevalence, frequency, and predictors of illicit OSD use in a group of injecting drug users (IDUs) and assessed if such use was associated with non-fatal overdoses. METHODS Semi-annual cross-sectional interviews conducted in Oslo, Norway (2006-2013), from 1355 street-recruited IDUs. Hurdle, logistic, and multinomial regression models were employed. RESULTS Overall, 27% reported illicit OSD use in the past four weeks; 16.8% methadone, 12.5% buprenorphine, and 2.9% both drugs. Almost 1/10 reported at least one non-fatal overdose in the past four weeks, and roughly 1/3 reported such experience in the past year. Use of additional drugs tended to be equally, or more prevalent among illicit OSD users than other IDUs. In terms of illicit OSD use being a risk factor for non-lethal overdoses, our results showed significant associations only for infrequent buprenorphine use (using once or less than once per week). Other factors associated with non-fatal overdoses included age, education, homelessness, as well as the benzodiazepines, stimulants, and heroin use. CONCLUSIONS Users of diverted OSD may represent a high-risk population, as they used more additional drugs and used them more frequently than other IDUs. However, illicit OSD use may be less harmful than previously assumed. After accounting for an extensive set of covariates, only infrequent illicit buprenorphine use, but not methadone use, was associated with non-fatal overdoses.

Gender differences in mortality and risk factors in a 13-year cohort study of street-recruited injecting drug users

BackgroundInjecting drug users (IDUs) are at risk of premature mortality. This study examined gender differences in mortality, risk factors, and causes of death among IDUs.MethodsIn a 13-year cohort study including 172 street-recruited IDUs from Oslo, Norway in 1997, interview data was merged with the National Cause of Death Registry. Crude mortality rate (CMR) and indirect standardized mortality ratio (SMR) were estimated with 95% confidence intervals (CI). A log-logistic multivariate survival analysis model was estimated for the full sample. For a smaller data set (1.1.1998-31.12.2004) the influence of substitution treatment and prison were assessed using cox regression survival analysis.ResultsEight females and 37 males died. Acute intoxications were the most common cause of death. Women were more at risk in the short-term, but more protected in the long-term. CMR was 16.0 [95% CI 8.0, 31.9] for women and 26.0 [95% CI 18.0, 35.8]) for men. SMR was 39.4 [95% CI 0.2, 220.8]) for women and 21.3 [95% CI 5.7, 54.1] for men. More women injected heroin (98% vs. 88% [x2 = 3.5, p = 0.063]), used prescription drugs (73% vs. 52% [x2 = 5.6, p = 0.018]) and combined these to inject (45% vs. 26% [x2 = 5.9, p = 0.015]). Mixing prescription drugs in heroin injections, and sex work (only women) were associated with decreased survival time. There were no gender differences in access to substitution treatment, while significantly more men had been in prison (74% vs. 51% [x2 = 7.5, p = 0.006]). The instance of substitution treatment and prison significantly decreased the mortality risk. Prison release increased the risk, but not statistically significantly.ConclusionsThere were gender differences in mortality and risk factors; sex work and prison were gender specific risk factors. These factors should be investigated further to better design future preventive measures.

Is opioid substitution treatment beneficial if injecting behaviour continues

BACKGROUND Opioid substitution treatment (OST) is recognised as an effective treatment for opioid dependence. Still, a subgroup of OST users continues to inject drugs. This study examines health risks and criminal activity in a population of needle exchange programme (NEP) participants by comparing those identified as current OST users to (i) those identified as former OST users and (ii) those with no OST experience. METHODS This was a semi-annual cross-sectional study conducted from 2002 to 2011. NEP participants were interviewed in Oslo, Norway (n=1760); 341 were identified as current OST users, 356 as former OST users and 1063 had no OST experience. The associations between OST status and health risk and criminal activity were assessed through univariate and multiple logistic regression analyses. RESULTS Among NEP participants, those currently in OST had fewer non-fatal overdoses (OR=0.5 [95% CI 0.3, 0.9]) compared to former OST users and those never in OST. Additionally, they were less likely to have injected frequently (OR=0.4 [95% CI 0.3, 06]), to have used heroin daily or almost daily (OR=0.3 [95% CI 0.2, 0.4]), and to have committed theft (OR=0.6 [95% CI 0.4, 1.0]) and engaged in drug dealing (OR=0.7 [95% CI 0.5, 0.9]) in the past month. Overall, there was a high level of polysubstance use and no group differences on this measure. CONCLUSIONS NEP participants who are currently in OST have substantially reduced health risks and criminal activity than other NEP participants. The high level of polysubstance use nevertheless poses a public health challenge.

Comparison of drugs used by nightclub patrons and criminal offenders in Oslo, Norway

The aim of this study was to investigate psychoactive drug use among nightclub patrons by analysing samples of oral fluid and compare with findings in blood samples from criminal suspects. We hypothesized that the profile of illicit drug use among nightclub patrons is different from what we observe in those forensic cases. Research stations were established outside nine popular nightclubs with different profiles and patron-characteristics in downtown Oslo. Data and sample collection was conducted on Fridays and Saturdays in March and May 2014. Individuals and groups who entered defined recruitment zones from 23:00 to 03:30 were invited to participate in this voluntary and anonymous study. Oral fluid was collected using the Intercept Oral Fluid Sampling Device. Methanol was added to increase the recovery of cannabinoids from the device. Sample preparation was performed using liquid-liquid extraction with ethyl acetate/heptane (4:1) after adding internal standards, ammonium carbonate buffer pH 9.3 and Triton X100. The first 80 samples were analysed for 122 substances, which included psychoactive medicinal drugs, classical illicit drugs and new psychoactive substances (NPS). Based on the findings and discussions with police and customs authorities, the remaining oral fluid samples were analysed for 46 substances. Among the 500 samples collected during the study period, we found illicit drugs in 25.4% and medicinal drugs in 4.2% of the samples. The most prevalent substances were: cocaine 14.6%, THC 12.4%, amphetamine/methamphetamine 2.8%, diazepam 1.2% and clonazepam 1.0%. Various NPS were found in 1.4% of the samples. The prevalence of drugs in blood samples from criminal suspects were for cocaine 3.4%, THC 34.7%, amphetamine/methamphetamine 37.0%, diazepam 12.0%, and clonazepam 29.3%. Multi-drug use was more common among criminal suspects (41.3%) than among club patrons (6.8%). The results showed that the drug use pattern among nightclub patrons was substantially different from the drug use pattern manifested by individuals apprehended by the police suspected for criminal conduct.

Hard drug use in Norway

E.J. Amundsen & A. Bretteville-Jensen: Hard drug use in Norway Background Hard drug use has a variety of heavy personal, social and economic costs. Knowing the size of the hard drug use population, the types of drugs consumed and modes of consumption can help policy makers design better policies and facilitate decision making. Intravenous drug users constitute one subgroup of hard drug users. The aim of this article is to describe 1) how the prevalence of intravenous drug use is estimated in Norway and 2) how available data sources give insight about other types of hard drug use even though we can not estimate the true extent of such use. Some policy consequences are outlined. Methods/Materials Overdose deaths and the mortality multiplier method were used to estimate the prevalence of intravenous drug users. Other materials were used to supply the picture of hard drug use in Norway. Results/Findings The prevalence of intravenous drug users in Norway increased steadily from the early 1980s, peaked in 2001, decreased until 2003 and then stabilized. Heroin is the substance of choice of most hard drug users in Norway and injection is the preferred means of intake. Amphetamines are also injected or consumed in other ways, while heavy use of cocaine in the treatment population is low. The use of more than one substance is common. Conclusion Preventing and reducing heroin injection is the main challenge facing Norwegian policy makers. Other drugs pose a problem as well. Wide availability of substitution treatment has a successful record of helping many former heroin users avoid heroin. The risk of relapsing remains high, however, and of dying after drop out or completion. Current knowledge of hard drug use is fragmented and improved monitoring of this high risk group should be prioritized.

A Method to Estimate Total Entry to Hard Drug Use: The Case of Intravenous Drug Use in Norway

Background/Aims: Epidemiological measures such as the prevalence and incidence of hard drug use are important tools for evaluating drug situations and drug policies. Models for drug use trajectories illustrate how temporary and lasting cessation of and relapse into hard drug use are other important elements in the overall picture of change in hard drug use over time. Estimating the total entry to hard drug use broadens the knowledge of the change in such use. Methods: The entry rate for hard drug use is defined as the sum of incident cases and relapses and estimated based on successive prevalence estimates and cessation rates. Results: The entry rate, as applied to the Norwegian case of intravenous drug use, increased from the mid-1980s to a peak in 2000, decreased up to 2003 and stabilized thereafter. The peak in Oslo appeared earlier (1998). The estimated level of the entry rate is sensitive to the rate of cessation. Conclusion: We conclude that it is possible to expand the description of hard drug use epidemics beyond estimates of prevalence and incidence. The entry rate supplies a useful tool for our understanding of drug situations and decision making regarding drug policies.

Are overdoses treated by ambulance services an opportunity for additional interventions? A prospective cohort study

AIMS To assess whether people who inject drugs (PWID) and who are treated for overdose by ambulance services have a greater mortality risk compared with other PWID, and to compare mortality risk within potentially critical time-periods (1 week, 1 month, 3 months, 6 months, 1 year, 5 years) after an overdose attendance with the mortality risk within potentially non-critical time-periods (time before and/or after critical periods). DESIGN A prospective cohort study. SETTING Oslo, Norway. PARTICIPANTS A total of 172 PWID street-recruited in 1997 and followed-up until the end of 2004. MEASUREMENTS Interview data linked to data from ambulance records, Norwegian Correctional Services, Opioid Substitution Treatment records and National Cause of Death Registry. Separate Cox regression models (one for each critical time-period) were estimated. FINDINGS Ambulance services treated 54% of the participants for an overdose during follow-up. The mortality rate was 2.8 per 100 person-years for those with an overdose and 3.3 for those without; the adjusted hazard ratio (HR) was 1.3 (95% CI = 0.6, 2.6, P = 0.482). Mortality risk was greater in all but the shortest critical time-period following ambulance attendance than in the non-critical periods. The mortality risk remained significantly elevated during critical periods, even when adjusted for total time spent in prison and substitution treatment. The HR ranged from 9.4 (95% CI = 3.5, 25.4) in the month after an overdose to 13.9 (95% CI = 6.4, 30.2) in the 5-year period. CONCLUSIONS Mortality risk among people who inject drugs is significantly greater in time-periods after an overdose attendance than outside these time-periods.

Where Have All the Young Girls Gone or Where Do All the Men Come from

A rough estimate indicates that women amount to one third of the heroin user population in Norway. However, among the youngest users females account and have accounted for a larger proportion. Given this greater representation of females in the younger age groups one would expect that the gender difference in the general population of users would be reduced over time due to a cohort effect. However, the ratio of male to female users has remained stable. The prevailing explanation for this stability is based on the claim that women are more likely to overcome their abuse. This paper addresses both the basis for the assumption of a missing cohort effect and examines an alternative explanation linked to the way into abuse rather than the way out. The study primarily draws upon two distinct data sources. The first body of material consists of interviews carried out in the period 1993–1997 with people attending the only needle exchange service in Oslo. The second data source consists of police records, which provide the number of persons arrested each year in the period 1984–1997 for using, possessing or selling heroin distributed by age and gender. We find that the age of injection debut has increased and that this is especially true for male users. Applying a simple quantitative model, the effect a change in recruitment may have on the male-to-female ratio is analysed. The results indicate that a higher debut age may have contributed to stabilizing the gender gap. The finding suggests that more research is needed on the conditions of recruitment in order to better predict the future population demographics and to avoid hasty and incorrect conclusions.

Questionable conclusions on cannabis and crime

In a paper published recently in this journal [1], Pedersen & Skardhamar examine whether cannabis users are at increased risk of being charged with criminal offences. They find an association between frequency of cannabis use in one year and risk of criminal charges in subsequent years. The association is statistically significant with respect to drug-specific crime only, and not to other types of criminal offences. The authors conclude that (i) ‘. . . use of cannabis does not seem to represent a risk factor for a general criminal involvement’ and (ii) that ‘. . . the fact that a considerable proportion of adolescents and young adults may come into contact with the penal system because of their involvement with cannabis must [. . .] give rise to concern. [. . .] The present study must be regarded as a new argument for the necessity to debate cannabis laws and the international conventions which regulate this area’. These conclusions are highly questionable, however, due to weaknesses in their data set and analyses: the model specifications and statistical power are inadequate; the outcome variable (charge with drugspecific crime) does not reveal with what type of drug the offender is charged (cannabis or hard drugs); and the vital control variable (hard drug use) does not cover the relevant time-period. Regarding the first conclusion: the models employed suffer from endogeneity problems, as both drug use and crime can be influenced by the same unobserved factors. Not controlling for unobserved heterogeneity may lead to biases in estimated coefficients. Moreover, the data set does not have the statistical power to support the stated conclusion due to the small number of observations and the complex model employed by the authors. In the multivariate analyses presented in Table 4 (p. 114), they applied a three-category variable on cannabis use in the preceding year: never, one to 10 times and 11+ times. The number of people who were charged with criminal offences other than drug-specific offences within these categories were 12, 7 and 2, respectively, whereas the number of confounding variables that were included in the models were 8, 9 and 10. It is not surprising, then, that the adjusted odds ratio (OR) is not statistically significant. Conducting a bivariate analysis, however, reveals that cannabis users, at age 20, have a statistically significantly higher risk of being charged with criminal offences (other than drug-specific offences) compared to non-users [6.5% versus 1.1%; unadjusted OR = 5.7 (our calculations are based on data presented in Table 2, p. 113 [1])]. In essence, the data suggest that cannabis users are at higher risk of being charged with criminal offences, both drug-specific offences and other criminal offences. Whether, or to what extent, it is the use of cannabis per se or characteristics of the cannabis user that may explain the elevated risk, however, cannot be determined by this study. Regarding the second conclusion: it should be obvious that illicit drug users are at increased risk of being charged with drug-specific crimes. However, whether cannabis users are at increased risk of being charged with cannabis offences cannot be determined by this study, as the crime register data do not contain any information on what kind of drugs the charges apply to. Hence, an unknown fraction of the cannabis users who were charged with a drug-specific crime may have been charged because of their use, possession or distribution of an illegal drug other than cannabis (e.g. amphetamines or ecstasy). The authors have tried to get around this problem by controlling for other illicit drug use at the age of 20. This is not a satisfactorily control, however, as it is likely that many of the cannabis users have initiated other illicit drug use in the subsequent years during which the charges occurred [2]. This means that a person who reports cannabis use at the age of 20 may very well have progressed into amphetamine use by the time of drug arrest and the criminal charge may well relate to hard drugs, not cannabis. Thus, the data cannot support that the charges are, in fact, related to cannabis offences and therefore do not support their claim that a significant proportion of young adults come into contact with the legal system because of their cannabis use. Given the above-mentioned weaknesses, we believe that Pedersen & Skardhamar’s conclusions lack empirical support. What they find is simply that cannabis drug users, many of whom have used illegal drugs in addition to other illegal drugs, have an increased risk of being charged with a drug-specific crime. It could still be the case that a non-ignorable fraction of illegal drug users in Norway have been arrested for their cannabis use but, unfortunately, the study by Pedersen & Skardhamar cannot illuminate the issue.