Abstract
We examined the effect of a case management intervention on drug treatment entry among injection drug users (IDUs) with and without comorbid antisocial personality disorder (ASPD). Injection drug users attending the Baltimore Needle Exchange Program who sought and were granted referrals to opioid agonist treatment were randomized to receive a strengths-based case management intervention or passive referral. Of 162 IDUs, 22.8% met the DSM-IV criteria for ASPD. Compared to those without ASPD, IDUs with comorbid ASPD who spent 25 or more minutes with their case manager prior to their treatment entry date were 3.51 times more likely to enter treatment than those receiving less than 5 min, adjusting for intervention status, race, and treatment site (95% confidence interval 1.04–11.89). Providing case management services to IDUs with comorbid ASPD may facilitate treatment entry and reduce the negative consequences of drug abuse.
Keywords: Antisocial personality disorder, Injection drug user, Case management
INTRODUCTION
The prevalence of antisocial personality disorder (ASPD) among injection drug users (IDUs) is upward of 75%.1–3 Injection drug users with ASPD are more likely to participate in needle sharing1,4 and high risk sexual behaviors4 associated with transmission of HIV, hepatitis C virus, and hepatitis B virus. Antisocial personality disorder is also associated with increased criminality,5 anxiety disorders,6 and a host of other negative psychosocial issues.7,8 However, unlike other psychiatric disorders, there are no pharmacologic treatments for ASPD and other treatments, such as psychotherapy, have largely proven unsuccessful.9
Because “antisocial” behaviors are associated with drug use and high risk behaviors,10 drug abuse treatment may be one way to curb antisocial acts because IDUs may no longer be engaging in illicit activities associated with drug use. The purpose of this analysis was to determine whether a case management intervention increased the proportion of IDUs with comorbid ASPD entering drug abuse treatment.
METHODS
Study participants were enrolled in the Treatment Retention Intervention (TRI), a randomized behavioral intervention in Baltimore, MD, USA described in greater detail elsewhere.11 Briefly, between April 2002 and January 2004, IDUs who requested and were granted an available opiate agonist treatment slot by the Baltimore Needle Exchange Program (NEP) program staff were invited to participate. After consenting to participate, subjects were randomized and a baseline interview was conducted before the treatment intake appointment. The baseline questionnaire ascertained information relating to sociodemographics, drug use, and drug treatment history.
Injection drug users randomized to the intervention were offered case management services immediately after their baseline interview. The intervention was based on the Strengths-Based Case Management (SBCM) model.12 Activities consistent with employment of the SBCM model include: (1) engagement, (2) strengths assessment, (3) personal case planning, and (4) resource acquisition.11,12 Examples of services provided by the case managers included referrals to health and social services, transportation, and employment.11
The presence of ASPD, generalized anxiety disorder (GAD), and major depressive disorder (MDD) was determined using the Structured Clinical Interview for the DSM-IV (SCID-I/SCID-II).13,14 Because some psychiatric symptoms may be difficult to differentiate from substance abuse-related symptoms and have been shown to significantly decrease after entry into drug treatment, the SCID was administered at the 1-month follow-up visit.15
Case managers recorded the total number and minutes of each contact after completion of the baseline questionnaire but before the appointment for treatment intake. The median number of minutes spent with a case manager before treatment entry for the whole sample was 25.11 Therefore, a variable was created to categorize case management time: 0 to 4 min (which included those with no exposure to the case management intervention), 5 to 24 min, and 25 or more minutes. Because the treatment intake date was within 7 days of the referral being granted, treatment entry was defined as entry into treatment within 7 days of the baseline interview. The primary outcome of interest and treatment entry was ascertained from record linkage with the Baltimore Substance Abuse System Incorporated (BSAS). Treatment consisted of publicly funded opiate agonist therapy, and BSAS maintains data for all publicly funded drug treatment programs in the city and provides data pertaining to treatment admissions and discharges.
Multiple logistic regression was utilized to examine the independent predictors of treatment entry. Of interest was the influence of ASPD and the case management intervention (main effects) as well as the interaction of the case management intervention and ASPD on treatment entry. The final model also controlled for randomization to the case management intervention and clustering by NEP site.
RESULTS
Of 245 IDUs enrolled, 162 (78.3%) completed the 1-month follow-up visit and were included in this analysis. Those who did not return for follow-up did not differ from participants completing the 1-month interview on any sociodemographic characteristics (p > 0.05), but were more likely to have been randomized to the case management intervention (61.4 vs 45.7%, p = 0.02). Of the 162 participants, the majority were black (75.9%) and male (67.9%); the median age was 38 years.
Lifetime prevalence of ASPD was 22.8% and a mean of 1.6 contacts was made between IDUs randomized to the intervention and the case managers before treatment entry. Injection drug users meeting the criteria for ASPD did not differ from other IDUs in terms of any sociodemographic characteristics but were more likely to have additional psychiatric comorbidities, including current MDD (18.9 vs 7.2%, p = 0.05), GAD (13.5 vs 2.4%, p = 0.02), and higher scores on the psychiatric subscale of the Addition Severity Index (ASI) (mean score 0.23 vs 0.13, p = 0.03). Compared to other IDUs, those with ASPD also scored higher on the drug use and legal and family/social subscales of the ASI. The proportion of HIV-positive IDUs with ASPD was somewhat greater than that of IDUs without ASPD (29.7 vs 17.6%; p = 0.16). Participants with comorbid ASPD were as likely as those without ASPD to enter opiate agonist treatment (30.8 vs 19.1%, p = 0.11).
In multivariate analyses (Table 1), IDUs with ASPD who received ≥25 min of case management time were more likely to enter treatment than those with fewer than 5 min or no exposure (adjusted odds ratio 3.51, 95% confidence interval 1.03, 11.9) after controlling for the main effects, randomization assignment, treatment site, and race and clustering by NEP site.
TABLE 1.
Independent predictors of treatment entry among treatment-seeking IDUs by multiple logistic regression
| Adjusted odds ratioa | 95% Confidence interval | |
|---|---|---|
| ASPDa 0–4 CM minutes | 1.00 | – |
| ASPDa 5–24 min | 2.19 | 0.06–76.9 |
| ASPDa 25+ minutes | 3.51 | 1.04–11.9 |
| Treatment site | ||
| 1 | 1.00 | – |
| 2b | – | – |
| 3 | 0.24 | 0.09–0.65 |
| 4 | 1.04 | 0.42–2.62 |
| 5b | – | – |
| 6 | 1.19 | 0.14–10.3 |
| Randomized to CM | 1.01 | 0.43–2.37 |
| Black | 0.89 | 0.29–2.75 |
aAdjusted for all other variables in the model; standard errors also adjusted for clustering by NEP site
bCannot be estimated because of zero values in one cell.
CM = Case management
DISCUSSION
Injection drug users with comorbid ASPD were just as likely as participants not meeting the criteria for ASPD to enter drug abuse treatment. This is surprising given that those with ASPD were more psychologically impaired, having a higher prevalence of comorbid MDD and GAD and greater scores on the ASI subscales for psychiatric, drug use, legal and family/social problems. In a similar study examining treatment entry among urban IDUs, Booth et al.2 found that the prevalence of ASPD was three times higher than that of our sample (75 vs 22.8%) and no association was found between ASPD and subsequent treatment entry.
Most interesting was that IDUs with comorbid ASPD who received a greater duration of case management were 3.51 times more likely to enter treatment than those receiving less time with their case manager. While similar findings were observed for the entire cohort,11 the strength of association between duration of case management and treatment entry was far greater for those with ASPD compared to the total sample.
Our study was limited by the fact that the main effects were not statistically significant although the interaction between ASPD and duration of case management was highly significant. This is likely due to a lack of power because analysis of the entire sample found the main effects to be significant.11 Selection bias may also be an issue given that only those who completed the 1-month follow-up were eligible for psychiatric assessment, and IDUs who were in the case management arm were significantly less likely to have been followed-up. Finally, because the study sample consisted of treatment-seeking IDUs from the NEP, results may not be generalizable to all IDUs in Baltimore.
Despite these limitations, it is encouraging that IDUs with comorbid ASPD who spent a greater amount of time with their case managers were more likely to enter drug treatment. Given that drug treatment has been shown to reduce HIV risk behaviors,16 the current intervention may be especially beneficial to IDUs with ASPD who have been shown to engage in more HIV risk behaviors.1,5 However, because the prevalence of ASPD was low compared with other studies,1,2 IDUs with comorbid ASPD in Baltimore may not be seeking treatment. If this is the case, interventions such as strengths-based case management to facilitate treatment entry may help avert the negative medical and social consequences associated with ASPD in the absence of medical treatment for this disorder.
Acknowledgements
The authors gratefully acknowledge support from the National Institute on Drug Abuse (grant nos. DA09225 and DA015604), Dr. David Vlahov, Dr. Peter Hartsock, staff of the Baltimore NEP and Baltimore Substance Abuse Systems, Inc. and associated drug treatment programs, and staff and participants of the TRI.
Footnotes
Havens is with the Center on Drug and Alcohol Research, University of Kentucky College of Medicine, Lexington, KY, USA; Cornelius is with the School of Social Work, University of Maryland, Baltimore, MD, USA; Ricketts, Huettner, and Strathdee are with the Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Latkin is with the Department of Health Policy and Management, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Bishai is with the Department of Population and Family Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Lloyd is with the School of Social Administration, Temple University, Philadelphia, PA, USA; Strathdee is with the Division of International Health and Cross-cultural Medicine, Department of Family Health Sciences, University of California San Diego School of Medicine, San Diego, CA, USA.
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