Developmental timing of first drug treatment and 10-year patterns of drug use

Modelling the progression of illicit substance use patterns from real-world evidence

AIMS

To investigate an innovative pharmacometrics approach that addresses the challenges of using real-world evidence to model the progression of illicit substance use.

METHODS

The modelling strategy analysed real-world data from the National Longitudinal Study of Adolescent to Adult Health (AddHealth) survey using survival analyses and differential equations. Respondents were categorized into drug-naïve, active users and nonusers. The transitions between categories were modelled using interval-censored parametric survival analysis. The resulting hazard rate functions were used as time-dependent rate constants in a differential equation system. Covariate models for sex and depression status were assessed.

RESULTS

AddHealth enrolled 6504 American teenagers (median age 16 years, range 11-21 years); this cohort was followed with five interviews over a 22-year period; the median age at the last interview was 38 years (range 34-45 years). The percentages of illicit drug users at Interviews 1-5 were 7.7%, 5.9%, 15.8%, 21.4% and 0.98%, respectively. The generalized gamma distribution emerged as the preferred model for the survival functions for transitions between categories. Age-dependent prevalence was obtained from the differential equation system. Active drug use was more prevalent in males, increased in adolescence and college years, peaked at 24 years, and decreased to low levels by 35 years. Depression, which was more frequent in females, increased the drug-naïve-active user transition rates but not the active user-nonuser and nonuser-active user transition rates. The evidence did not support an interaction between sex and depression.

CONCLUSIONS

The model provided a satisfactory approximation for the age-dependent progression of illicit substance use from preadolescence to early middle age.

AMPed-up adolescents: The role of age in the abuse of amphetamines and its consequences on cognition and prefrontal cortex development

Adolescent use of amphetamine and its closely related, methylated version methamphetamine, is alarmingly high in those who use drugs for nonmedical purposes. This raises serious concerns about the potential for this drug use to have a long-lasting, detrimental impact on the normal development of the brain and behavior that is ongoing during adolescence. In this review, we explore recent findings from both human and laboratory animal studies that investigate the consequences of amphetamine and methamphetamine exposure during this stage of life. We highlight studies that assess sex differences in adolescence, as well as those that are designed specifically to address the potential unique effects of adolescent exposure by including groups at other life stages (typically young adulthood). We consider epidemiological studies on age and sex as vulnerability factors for developing problems with the use of amphetamines, as well as human and animal laboratory studies that tap into age differences in use, its short-term effects on behavior, and the long-lasting consequences of this exposure on cognition. We also focus on studies of drug effects in the prefrontal cortex, which is known to be critically important for cognition and is among the later maturing brain regions. Finally, we discuss important issues that should be addressed in future studies so that the field can further our understanding of the mechanisms underlying adolescent use of amphetamines and its outcomes on the developing brain and behavior.

Trajectories of heroin use: A 15-year retrospective study of Mexican-American men who were affiliated with gangs during adolescence

BACKGROUND

Heroin use is a public health concern in the United States. Despite the unique etiology and patterns of heroin use among U.S. Latinos, long-term heroin trajectories and health consequences among Latinos are not well understood. This study aims to document the distinct heroin use trajectories for a group of street-recruited (non-treatment), young adult Mexican American men living in a disadvantaged community who were affiliated with gangs during their youth.

METHODS

One-time interviews conducted between 2009-2012 in San Antonio, TX collected retrospective data from a sample of 212 Mexican American young adult men who reported using heroin at least once. Group-based trajectory modeling was applied to determine discrete developmental trajectories of heroin use. ANOVA, Chi square tests, and multinomial logistic regression examined current (past year) social and health indicators among each trajectory group.

RESULTS

Five discrete heroin trajectories groups were identified: low use (n = 65); late accelerating (n = 31); early decelerating (n = 26); late decelerating (n = 38); and stably high (n = 52). Varying social and health consequences were found among the trajectory groups.

CONCLUSION

This study describes the unique heroin use trajectories and social and health outcomes among a high-risk subgroup of Mexican American men. The findings suggest that early intervention and intervention available in easy to access non-treatment spaces may be especially useful for groups of people who use relatively less heroin.

Sex differences in an old adult sample with substance use disorder: A 6 months follow-up study

Substance use disorder (SUD) is a worldwide concern that has its own particularities regarding age and sex. This study aims to assess the differences between old SUD women and men regarding socio-demographics, clinical factors and outcomes. A 6-months follow-up longitudinal study was conducted in an outpatient center, on a convenience sample of 115 SUD old adults (≥65 years old, average age of 71.57). Descriptive, bivariate, and multivariate analyses were performed. Data showed statistical significant differences between men and women related to sociodemographic variables (marital status, coexistence, criminal records and stress factors), medical and psychiatric conditions (women suffer higher rates of depression and anxiety, with worse health-related quality of life), family records (women had more presence of family psychiatric records) and SUD related parameters (men tend to use more alcohol, had an early onset, consume higher doses, report more craving and more tobacco life use while women had higher rates of prescription drugs use). At 6-month follow-up, the whole sample showed excellent rates of adherence and abstinence, without sex differences. The study points out sex differences on several sociodemographic and clinical variables, indicating their specific needs. This research could facilitate better approaches by considering a sex perspective in SUD old adults.

Generational trends and patterns in readmission within a statewide cohort of clients receiving heroin use disorder treatment in Maryland, 2007-2013

The recent rise in opioid-related overdose deaths stresses the importance of understanding how heroin use disorders persist and what interventions are best suited for treating these illnesses. Trends show that there are diverse pathways leading to heroin use disorder that span multiple generations, but little is known about how different generations utilize and respond to treatment. This study provides insight into treatment utilization for young, middle-aged, and older adults by examination of an unusually rich longitudinal dataset of substance use disorder clients in Maryland who were treated for heroin use. Results show that clear patterns of treatment readmission emerge across generations in treatment-naïve clients with regard to gender, ethnicity, employment, geographical region, and treatment type/intensity. In particular, Millennials comprise the majority of the clients receiving heroin use disorder treatment and are the largest contributor to these readmission patterns. Millennials are also given opioid maintenance therapy (OMT) more frequently than other generations, while exhibiting a strong avoidance to treatment. Generational differences in treatment decisions and outcomes over the course of a treatment career are important for understanding the nature of the current opioid epidemic, and can play an important role in directing heroin use disorder treatment efforts and improving models of care.

Sex and gender differences in substance use disorders

The gender gap in substance use disorders (SUDs), characterized by greater prevalence in men, is narrowing, highlighting the importance of understanding sex and gender differences in SUD etiology and maintenance. In this critical review, we provide an overview of sex/gender differences in the biology, epidemiology and treatment of SUDs. Biological sex differences are evident across an array of systems, including brain structure and function, endocrine function, and metabolic function. Gender (i.e., environmentally and socioculturally defined roles for men and women) also contributes to the initiation and course of substance use and SUDs. Adverse medical, psychiatric, and functional consequences associated with SUDs are often more severe in women. However, men and women do not substantively differ with respect to SUD treatment outcomes. Although several trends are beginning to emerge in the literature, findings on sex and gender differences in SUDs are complicated by the interacting contributions of biological and environmental factors. Future research is needed to further elucidate sex and gender differences, especially focusing on hormonal factors in SUD course and treatment outcomes; research translating findings between animal and human models; and gender differences in understudied populations, such as those with co-occurring psychiatric disorders and gender-specific populations, such as pregnant women.

Initiation of Addiction Treatment and Access to Services: Young Adults' Accounts of Their Help-Seeking Experiences

Substance addiction in young adults is particularly problematic. Yet, much remain at stake in understanding the specifics of this population's access to services. The objective of this study is to explore young adults' initiation of substance misuse treatment. Our study sample was composed of 35 individuals aged 18 to 30 with problematic psychoactive substance use who have been identified in criminal courts, hospital emergency departments, and Health and Social Services Centers in Québec (Canada). A thematic analysis was performed on the 62 semi-structured interviews conducted with participants. Three components emerged. First, personal elements-expectations, individual motivations, perceptions of use, and capacity to control it-influence initiation of substance misuse treatment. Second, family and peers have noticeable influences. Finally, system characteristics and prior care experiences also shape the process. Consideration should be given to tailor interventions that can reach young adults and encourage them to initiate appropriate care.

Gender and race/ethnic differences in the persistence of alcohol, drug, and poly-substance use disorders

AIMS

To examine gender and racial/ethnic differences in the effect of substance use disorder (SUD) type on SUD persistence.

METHODS

Data were provided by 1025 women and 1835 men from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) to examine whether gender and race/ethnicity (Non-Hispanic White, Black, Hispanic) moderate the effects of DSM-IV defined past-12 month SUD type (alcohol, drug, poly-substance) on SUD persistence at 3-year follow-up, controlling for covariates. Using gender-stratified weighted binary logistic regression, we examined predictors of SUD persistence, tested an SUD type by race/ethnicity interaction term, and calculated and conducted Bonferroni corrected pairwise comparisons of predicted probabilities.

RESULTS

SUD persistence rates at 3-year follow-up differed for SUD type by gender by race/ethnicity sub-group, and ranged from 31% to 81%. SUD persistence rates were consistently higher among poly-substance users; patterns were mixed in relation to gender and race/ethnicity. Among women, alcohol disordered Hispanics were less likely to persist than Whites. Among men, drug disordered Hispanics were less likely to persist than Whites. Also, Black men with an alcohol or drug use disorder were less likely to persist than Whites, but Black men with a poly-substance use disorder were more likely to persist than Hispanics.

CONCLUSIONS

The effect of SUD type on SUD persistence varies by race/ethnicity, and the nature of these relationships is different by gender. Such knowledge could inform tailoring of SUD screening and treatment programs, potentially increasing their impact.

Mortality among individuals accessing pharmacological treatment for opioid dependence in California, 2006-10

AIMS

To estimate mortality rates among treated opioid-dependent individuals by cause and in relation to the general population, and to estimate the instantaneous effects of opioid detoxification and maintenance treatment (MMT) on the hazard of all-cause and cause-specific mortality.

DESIGN

Population-based treatment cohort study.

SETTING

Linked mortality data on all individuals first enrolled in publicly funded pharmacological treatment for opioid dependence in California, USA from 2006 to 2010.

PARTICIPANTS

A total of 32 322 individuals, among whom there were 1031 deaths (3.2%) over a median follow-up of 2.6 years (interquartile range = 1.4-3.7).

MEASUREMENTS

The primary outcome was mortality, indicated by time to death, crude mortality rates (CMR) and standardized mortality ratios (SMR).

FINDINGS

Individuals being treated for opioid dependence had a more than fourfold increase of mortality risk compared with the general population [SMR = 4.5, 95% confidence interval (CI) = 4.2, 4.8]. Mortality risk was higher (1) when individuals were out-of-treatment (SMR = 6.1, 95% CI = 5.7, 6.5) than in-treatment (SMR = 1.8, 95% CI = 1.6, 2.1) and (2) during detoxification (SMR = 2.4, 95% CI = 1.5, 3.8) than during MMT (SMR = 1.8, 95% CI = 1.5, 2.1), especially in the 2 weeks post-treatment entry (SMR = 5.5, 95% CI = 2.7, 9.8 versus SMR = 2.5, 95% CI = 1.7, 4.9). Detoxification and MMT both independently reduced the instantaneous hazard of all-cause and drug-related mortality. MMT preceded by detoxification was associated with lower all-cause and other cause-specific mortality than MMT alone.

CONCLUSIONS

In people with opiate dependence, detoxification and methadone maintenance treatment both independently reduce the instantaneous hazard of all-cause and drug-related mortality.

Characterizing longitudinal health state transitions among heroin, cocaine, and methamphetamine users

AIMS

Characterize longitudinal patterns of drug use careers and identify determinants of drug use frequency across cohorts of primary heroin, methamphetamine (MA) and cocaine users.

DESIGN

Pooled analysis of prospective cohort studies.

SETTINGS

Illicit drug users recruited from community, criminal justice and drug treatment settings in California, USA.

PARTICIPANTS

We used longitudinal data on from five observational cohort studies featuring primary users of heroin (N=629), cocaine (N=694) and methamphetamine (N=474). The mean duration of follow-up was 20.9 years.

MEASUREMENTS

Monthly longitudinal data was arranged according to five health states (incarceration, drug treatment, abstinence, non-daily and daily use). We fitted proportional hazards (PH) frailty models to determine independent differences in successive episode durations. We then executed multi-state Markov (MSM) models to estimate probabilities of transitioning between health states, and the determinants of these transitions.

FINDINGS

Across primary drug use types, PH frailty models demonstrated durations of daily use diminished in successive episodes over time. MSM models revealed primary stimulant users had more erratic longitudinal patterns of drug use, transitioning more rapidly between periods of treatment, abstinence, non-daily and daily use. MA users exhibited relatively longer durations of high-frequency use. Criminal engagement had a destabilizing effect on health state durations across drug types. Longer incarceration histories were associated with delayed transitions toward cessation.

CONCLUSIONS

PH frailty and MSM modeling techniques provided complementary information on longitudinal patterns of drug abuse. This information can inform clinical practice and policy, and otherwise be used in health economic simulation models, designed to inform resource allocation decisions.

Does age at first treatment episode make a difference in outcomes over 11 years?

This study examines the associations between age at first substance use treatment entry and trajectory of outcomes over 11 years. We found significant differences in individual and treatment characteristics between adult intakes first treated during young adulthood (25 years or younger) and those first treated at an older age. Compared to their first treated older age counterparts matched on demographics and dependence type, those who entered first treatment during young adulthood had on average an earlier onset for substance use but a shorter duration between first substance use and first treatment entry; they also had worse alcohol and other drug outcomes 11 years post treatment entry. While subsequent substance use treatment and 12-step meeting attendance are important for both age groups in maintaining positive outcomes, relationships varied by age group. Findings underline the importance of different continuing care management strategies for those entering first treatment at different developmental stages.

Patterns of treatment utilization and methamphetamine use during first 10 years after methamphetamine initiation

The study examined joint trajectories of methamphetamine (MA) use and substance abuse treatment utilization and identified differences among pattern groups for a sample of 348 treated for MA use. Results from group-based trajectory modeling showed that treatment utilization during the first 10 years after initiation of MA use could be categorized into three distinctive patterns: about half the MA users have a pattern of low treatment utilization; one-fourth follow a quicker-to-treatment trajectory with higher probability of treatment during the first 5 years of MA use and less treatment in the next 5 years; and one-fourth have a slower-to-treatment trajectory with more treatment during the second half of the 10-year period. Four MA use patterns were identified: consistently low use, moderate, and high use, as well as a decreasing use pattern. Periods of greater likelihood of treatment participation were associated with periods of decreasing or lower frequency of MA use.