Prediction of drug abuse recurrence: a Swedish National Study

The number of episodes of major psychiatric and substance use disorders as an index of genetic risk and genetic heterogeneity

We investigate whether number of episodes (NoEs) meaningfully reflect genetic risk and genetic heterogeneity for five primary disorders-Drug Use Disorder (DUD), Alcohol Use Disorder (AUD), Major Depression (MD), Bipolar Disorder (BD), and Schizophrenia (SZ) ascertained from Swedish population registries. We utilize Genetic Risk Ratios (GRR)-defined as the ratio of the genetic risk for secondary disorders to the genetic risk for the primary disorder-derived from Family Genetic Risk Scores (FGRS). For all five primary disorders, genetic risk rose robustly with increasing NoEs. For both AUD and DUD, the GRR for all six secondary disorders-selected to have a likely genetic relationship with the particular primary disorder-declined with increasing NoEs so that cases of AUD and DUD with high versus low NoEs had both a higher genetic risk and a purer genetic signal. With MD, genetic risk maximized at an intermediate NoEs. While the GRRs for AUD and DUD in MD cases dropped sharply with increasing NoEs, GRR for BD increased. For BD, genetic risk rose sharply with increasing NoEs while for all secondary disorders the GRRs showed a mixture of modest increases and decreases. Like AUD and DUD, but even more markedly, selecting BD cases with high rates of recurrence would produce a sample with a high overall genetic risk and a relatively homogeneous genetic signal. For SZ, genetic risk rose moderately with increases in NoEs. GRRs for other non-affective psychoses (ONAP) and autism spectrum disorder (ASD) fell quite slowly with increasing NoEs, and more rapidly for other secondary disorders. Cases of SZ with high recurrence rates had a high genetic risk and a relatively pure signal, albeit with contributions from ONAP and ASD. In summary, NOEs are a robust index of genetic risk and genetic heterogeneity across our primary disorders with important inter-disorder differences.

Risk of suicidal behavior as a function of alcohol use disorder typologies: A Swedish population-based study

BACKGROUND AND AIMS

Alcohol use disorder (AUD) is one of the strongest predictors of suicidal behavior. Here, we measured risk of suicide attempt and death as a function of AUD typologies.

DESIGN

We used AUD typologies from previous latent class analysis: (i) externalizing subtype (characterized by externalizing symptomatology and early age of onset; individuals in this group have lower education and higher familial/social difficulties); (ii) subtype described by minimal psychopathology; and (iii) internalizing subtype (characterized by internalizing symptomatology and later age of onset; individuals in this group have higher education). We used class membership to predict distal outcomes (attempt and death) and performed regressions to evaluate whether differences in suicidal behavior were explained by the group characteristics (sex, age of onset, number and type of AUD registrations, familial/genetic risk for AUD, externalizing and internalizing behaviors, socio-economic indicators, marital status and childhood family status). We also evaluated the effect of suicide attempt prior to AUD.

SETTING AND PARTICIPANTS

Based on longitudinal Swedish registry data, we included 217 074 individuals with AUD born 1950-80.

MEASUREMENTS

Suicide attempts were identified using medical registers and deaths using the mortality register.

FINDINGS

Individuals with the externalizing subtype had higher risks of suicidal behavior than other groups [attempt: externalizing versus minimal psychopathology: odds ratio (OR) = 1.35, 95% confidence interval (CI) = 1.35, 1.35; externalizing versus internalizing: OR = 1.47, 95% CI = 1.46, 1.48; death: externalizing versus minimal psychopathology: OR = 1.57, 95% CI = 1.57, 1.58; externalizing versus internalizing: OR = 1.99, 95% CI = 1.93, 2.06]. Individuals with minimal psychopathology had higher risks than those with internalizing symptomatology (attempt: OR = 1.09, 95% CI = 1.08, 1.10, death: OR = 1.26, 95% CI = 1.23, 1.30). These differences were explained by age at registration and were related to the number of registrations, sex, education, family disruption and suicide attempt prior to AUD.

CONCLUSIONS

Among people in Sweden, considering alcohol use disorder (AUD) heterogeneity appears to be a meaningful way to evaluate suicide risk. The highest risk of suicide attempt and death occurs in the externalizing subtype of AUD, followed by the minimal psychopathology subtype, and then the internalizing subtype.

Indications of alcohol or drug use disorders in five different national registers in Sweden: a cross-sectional population-based study

OBJECTIVE

The purpose of this study is to examine the prevalence of indications of alcohol or drug use disorders in five different national Swedish registers and to investigate the correlation between these registers. Furthermore, the intent is to investigate whether combining data from different registers increases the prevalence of these indications in the population due to the identification of different demographic groups in different registers.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

Individuals living in Sweden aged 20-64 years in 2006, n=5 453 616.

PRIMARY OUTCOME

National registers included the Registers of Inpatient Care, Outpatient Care, Medications, Social Insurance and Convictions. Demographic variables were sex, age, migrant status, education and civil status. Indications of alcohol or drug use disorders were presented as prevalence in percentage (%), correlation was examined using phi correlation coefficients and differences across demographic factors were studied using logistic regression.

RESULTS

The prevalence of an indication of alcohol or drug use disorder varied between registers, meaning that prevalence increased when all registers were considered together. The prevalence of alcohol use disorder increased by 60% and 66% among men and women, respectively, while the prevalence of drug use disorder increased by 45% and 80% among men and women, respectively, when all registers were combined, compared with only using the register with the highest prevalence. Registers contributed different indications of drug and alcohol use disorders.

CONCLUSIONS

Accurate estimates of alcohol or drug use disorders are critical for healthcare and rehabilitation. This study shows that using a single register alone underestimates the burden of disease unevenly, while combining a range of registers can provide a more accurate picture.

Multifractal test for nonlinearity of interactions across scales in time series

The creativity and emergence of biological and psychological behavior tend to be nonlinear, and correspondingly, biological and psychological measures contain degrees of irregularity. The linear model might fail to reduce these measurements to a sum of independent random factors (yielding a stable mean for the measurement), implying nonlinear changes over time. The present work reviews some of the concepts implicated in nonlinear changes over time and details the mathematical steps involved in their identification. It introduces multifractality as a mathematical framework helpful in determining whether and to what degree the measured series exhibits nonlinear changes over time. These mathematical steps include multifractal analysis and surrogate data production for resolving when multifractality entails nonlinear changes over time. Ultimately, when measurements fail to fit the structures of the traditional linear model, multifractal modeling allows for making those nonlinear excursions explicit, that is, to come up with a quantitative estimate of how strongly events may interact across timescales. This estimate may serve some interests as merely a potentially statistically significant indicator of independence failing to hold, but we suspect that this estimate might serve more generally as a predictor of perceptuomotor or cognitive performance.

Predictors of dropout from treatment among patients using specialized addiction treatment centers

OBJECTIVES

This study investigated the use of outpatient care, and sociodemographic and clinical characteristics of patients with substance-related disorders (SRD) to predict treatment dropout from specialized addiction treatment centers. The study also explored risks of adverse outcomes, frequent emergency department (ED) use (3+ visits/year), and death, associated with treatment dropout within the subsequent 12 months.

METHODS

The study examined a cohort of 16,179 patients who completed their last treatment episode for SRD between 2012 and 13 and 2014-15 (financial years: April 1 to March 31) in 14 specialized addiction treatment centers using Quebec (Canada) health administrative databases. We used multivariable logistic regressions to measure risk of treatment dropout (1996-96 to 2014-15), while we used survival analysis controlling for sex and age to assess the odds of frequent ED use and death in 2015-16.

RESULTS

Of the 55 % of patients reporting dropout from SRD treatment over the 3-year period, 17 % were frequent ED users, and 1 % died in the subsequent 12 months. Patients residing in the most socially deprived areas, having polysubstance-related disorders or personality disorders, and having previously dropped out from specialized addiction treatment centers had increased odds of current treatment dropout. Older patients, those with a history of homelessness, past SRD treatment, or more concurrent outpatient care outside specialized addiction treatment centers had decreased odds of treatment dropout. Patients who dropped out were subsequently at higher risk of frequent ED use and death.

CONCLUSIONS

This study highlighted that patients with more severe problems and previous dropout may need more sustained and adequate help to prevent subsequent treatment dropout. Specialized addiction treatment centers may consider enhancing their follow-up care of patients over a longer duration and better integrating their treatment with other outpatient care resources to meet the multiple needs of the more vulnerable patients using their services.

Exploring factors jointly associated with recurrent relapse and dropout of methadone maintenance treatment clients in Guangdong, China: A retrospective cohort study

BACKGROUND

Clients receiving methadone maintenance treatment (MMT) may experience multiple relapses, which may lead to dropout. However, previous studies mostly only explored the influencing factors of relapse or dropout separately. In this study, we investigated the influencing factors jointly associated with both recurrent relapse and dropout.

METHODS

This study was conducted in 16 MMT clinics in Guangdong, China. Data on the clients' demographic characteristics; drug-related behavior; HIV, HCV, and urine morphine test results; and daily methadone doses were collected. The outcomes were time to recurrent relapse and time to dropout. A joint frailty model was used to explore factors jointly associated with recurrent relapse and dropout. The hazard ratios (HRs) of the covariates in the multivariable model were adjusted, with HR > 1 indicating a faster time to recurrent relapse and dropout.

RESULTS

Among 1539 clients, 39.5% had ≥ 2 relapse events, and 90.8% of the clients dropped out. A high attendance rate was protective for recurrent relapse (HR_50-80%=0.63, 95% CI: 0.51, 0.79; HR_>80%=0.35, 95% CI: 0.28, 0.44) and dropout (HR_50-80%=0.56, 95% CI: 0.47, 0.68; HR_>80%=0.27, 95% CI: 0.23, 0.33). Being married (HR=0.80, 95% CI: 0.67, 0.96), having a fair relationship with family (HR=0.79, 95% CI: 0.67, 0.93) and drug injection (HR=0.80, 95% CI: 0.67, 0.96) were also protective for recurrent relapse. Female (HR=0.64, 95% CI: 0.50, 0.82) and a high methadone dose (≥60 ml/day; HR=0.79, 95% CI: 0.65, 0.96) were protective for dropout, and a longer traveling time to the clinic (>60 min; HR=1.59, 95% CI: 1.20, 2.10) was associated with an increased risk of dropout.

CONCLUSIONS

It is common for clients to experience recurrent relapse and dropout. The findings suggest that MMT clinics should provide holistic interventions and appropriate methadone doses for clients to improve treatment compliance.