RESEARCH AND PRACTICE |
Jesse B. Milby, Joseph E. Schumacher, Michelle J. Freedman, and Rudy E. Vuchinich are with the University of Alabama at Birmingham. Dennis Wallace is with Rho Federal Systems Division Inc, Chapel Hill, NC.
Correspondence:
| ABSTRACT |
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Objectives. Housing typically is not provided to homeless persons during drug abuse treatment. We examined how treatment outcomes were affected under 3 different housing provision conditions.
Methods. We studied 196 cocaine-depende
Results. The ACH group had a higher prevalence of drug abstinence than the NACH group (after control for treatment attendance), which in turn had a higher prevalence than the NH group. All 3 groups showed significant improvement in maintaining employment and housing.
Conclusions. The results of this and previous trials indicate that providing abstinence-cont
| INTRODUCTION |
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Providing effective drug abuse intervention for homeless substance abusers is a daunting challenge because of this population’s high morbidity, poverty, and social instability.12–19 In particular, homelessness necessitates a continuous search for food and shelter, which seriously interferes with treatment participation. For example, O’Brien et al.20 found that day treatment reduced drug abuse among non-homeless participants but that no homeless participants were retained in treatment.
Previous trials have shown that provision of housing for homeless substance abusers while they are undergoing behavioral day treatment improved addiction outcomes and resulted in less homelessness.21,22 In those studies, housing was available only when participants were drug-free; that is, housing was "abstinence-con
Such a contingency differs greatly from the typical "housing first" approach to fighting homelessness, in which housing is provided with no abstinence requirements, on the premise that housing provision alone will lead to improvement. In theory, non–abstinence-
In the trial, we examined how providing housing with and without an abstinence contingency affected drug use, homelessness, and employment among cocaine-depende
| METHODS |
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The final study set consisted of 196 participants randomly divided into 3 groups: those receiving abstinence-cont.
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During the study period, urine testing was conducted for cocaine, marijuana, and alcohol use. Specimens were obtained from randomly selected participants twice weekly during phases 1 and 2 and once weekly during phase 3. During phase 1, ACH participants received rent-free housing after 2 consecutive drug-negative urine tests. NACH participants received rent-free housing in similar buildings in a different neighborhood after 2 consecutive urine tests, regardless of test results. In 1997 (midstudy) the ACH and NACH groups switched housing units with one another to balance any housing or neighborhood influences. NH participants received no program-provide
For ACH participants, a drug-positive urine test resulted in immediate removal from housing to a shelter. Abstinence was considered reestablished with 2 consecutive drug-negative tests, after which ACH participants were immediately moved back to program housing. NACH participants remained in housing as long as they gave scheduled urine specimens, regardless of results. Exceptions occurred because of severe misbehavior at housing sites (e.g., damaging apartments, on-premise drug use, having overnight guests). Such behavior, which was observed in only 22 participants, was grounds for immediate housing restriction for both ACH and NACH participants for 1 week, during which the participant was placed in a shelter.
During phase 2, ACH and NACH participants were charged a monthly rent of $161.00; participants earned rent money through work therapy or other employment. Neither ACH nor NACH participants were removed from housing for not paying rent. All participants were offered work therapy at a minimum wage of $5.25 per hour. Continuation of work therapy was not contingent on abstinence, but the housing contingency remained in place for ACH participants.
During phase 3, ACH and NACH participants could remain in program housing if housing slots were available, but no abstinence contingency was imposed for any of the participants. All groups were offered aftercare group meetings once weekly for 6 months, with individual counseling provided as needed.
Outcome Measures Participants were assessed by interviewers not aware of the participants’ treatment group at baseline and 2, 6, and 12 months after baseline. Participants were given backpacks containing personal hygiene items after baseline assessment and were paid $25 for each completed follow-up assessment. A nonparticipant "tracker" was tasked with locating participants and transporting them to the follow-up assessments. The tracker was paid $25 for each completed follow-up assessment.
Drug testing was conducted with the OnTrak TesTstik (Roche Diagnostic Systems, Somerville, NJ). To encourage compliance, clients were paid $3 per specimen during months 5 through 10 and $5 per specimen during months 11 and 12 for 4 randomly selected specimens out of the 8 scheduled urinalysis tests. If a urinalysis result was inconclusive, the original specimen was tested 1 or 2 more times, and the 2 most consistent results determined the data point. Urinalysis test results were used to implement the housing contingencies and to construct 2 drug use–dependent variables: (1) the proportion of participants, by group, whose urine tests all were drug-negative each week, and (2) the longest string of consecutive weeks of abstinence attained by each participant. Data from specimens obtained at follow-up are not reported here.
Homelessness and employment were measured with the Retrospective Interview for Housing, Employment, and Treatment History completed by each participant.27 Days employed was the number of days the participant was fully employed (i.e., worked at least 7 hours per day) the last 60 days. Homelessness was measured by number of days housed during the past 60 days.
Treatment Attendance and Study Retention
Treatment attendance was recorded in a counselor-verif
Analysis
We employed an intention-to-tr
For our estimate of weekly abstinence prevalence, we used generalized estimating equation (GEE) extensions of generalized linear models to assess differences between housing groups and to determine whether group differences in abstinence were modified by treatment attendance.28 We used an initial model to estimate abstinence as a function of housing group and study phase. We used Wald tests based on Liang and Zeger’s procedure28 to test for group differences across each phase. We used a second model to estimate abstinence as a function of housing group, study phase, and treatment attendance. To estimate consecutive weeks of abstinence, we used an analysis-of-var
We used Wilcoxon rank sum tests to assess group differences in days housed and days employed. Changes in days housed and days employed from baseline to 6 months and from baseline to 12 months were analyzed by treatment group and overall with paired t tests.
| RESULTS |
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On the basis of previous experience,29,30 we defined participants who completed 20 or more treatment days during a single phase as high attenders for that phase. Participants who had fewer than 20 treatment days during a phase were defined as low attenders for that phase. During phase 1, mean (SD) days attended for the NH, NACH, and ACH groups were 18.3 (12.2), 26.7 (9.3), and 24.9 (11.5), respectively, with strong evidence of differences between the NH group and the NACH group (P < .0001) and the NH group and the ACH group (P = .0010) but no evidence of difference between the NACH group and the ACH group (P = .35). After summation across both phases, mean (SD) days attended for the NH, NACH, and ACH groups were 32.0 (28.4), 56.6 (29.9), and 50.1 (29.1), respectively, with strong evidence of a difference between the NH group and the NACH group (P < .0001) and the NH group and the ACH group (P = .0005), but no evidence of a difference between the NACH group and the ACH group (P = .21).
We used a second GEE model to examine the abstinence prevalence as a function of housing group, phase, and attendance. As shown in Table 2, attendance modified the housing group effect. In both phase 1 and phase 2, low attenders in the ACH and NACH groups had greater abstinence than low attenders in the NH group, with no evidence of a difference between NACH and ACH low attenders. Among high attenders, the phase 1 data showed a clear trend for higher abstinence prevalence in the ACH group, followed by the NACH group, with the lowest abstinence again in the NH group. The phase 2 results for high attenders were comparable to the results for low attenders, but the point estimates suggested greater difference between ACH and NACH high attenders than was observed between ACH and NACH low attenders.
Results for consecutive weeks of abstinence differed somewhat from results for abstinence prevalence. To assess the effect of attendance on the relationship between housing group and sustained abstinence, we fit a series of linear models with an ordinal measure of attendance that included treatment days in both phases. Participants were classified as low attenders if their attendance was low during both phase 1 and phase 2, as intermediate attenders if their attendance was low during one phase and high during the other, and as high attenders if their attendance was high during both phases. A model including housing group, attendance, and an interaction term showed no evidence of effect modification (P = .34 for the interaction). A model without the interaction term showed that attendance acted as an intervening variable for the housing group effect. This analysis provided strong evidence of an overall housing group effect after adjustment for attendance (P = .0080) and an effect of attendance on abstinence (P < .0001). The mean adjusted consecutive weeks of abstinence for the NH, NACH, and ACH groups were 5.28, 4.68, and 7.32, respectively, with evidence of a difference between the ACH group and the NH group (P = .024) and between the ACH group and the NACH groups (P = .0031), but no evidence of a difference between the NACH group and the NH group (P = .51).
As previous studies of homelessness have observed,21,22 our participants missed scheduled urine tests for administrative and other reasons. Data missing for administrative reasons were comparable across groups, ranging from 17% to 21% in phase 1 and from 8% to 11% in phase 2. Data missing for other reasons differed across groups and increased throughout the study, with phase 1 missing rates of 43%, 21%, and 14% and phase 2 missing rates of 67%, 43%, and 35% for the NH, ACH, and NACH groups, respectively. Although these rates are less than ideal for study purposes, sensitivity analyses indicated that our results are robust across all approaches to handling the missing data (data not shown).
Homelessness Outcomes
Results for days housed are shown in Figure 2 and provide strong evidence of within-group housing changes from baseline to 12 months for all groups (P < .0001) and for each group (ACH, P < .0014; NACH, P < .0006; NH, P < .021). No significant within-group differences from baseline to 6 months were found for any group, and the groups did not differ significantly from each other at any time point.
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Gender-Specific
| DISCUSSION |
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The results related to our second hypothesis, that abstinence-cont
The consistent trend of higher weekly abstinence prevalence in the ACH group compared with the NACH group and the significantly higher weekly abstinence prevalence among high attenders in the ACH group compared with the NH group (but not in the NACH group vs the NH group) all are consistent with our second hypothesis and support the clinical and administrative value of providing abstinence-cont
In our previous studies,21,22 abstinence among the housed group was clearly superior, but the provision of housing and the abstinence contingency were confounded for the housed group. Those studies and the current study suggest that provision of abstinence-cont
Unlike previous studies,21,22 participants in the ACH and NACH groups in the current study could work and earn a stipend when they were not abstinent, and ACH participants could use their earnings to purchase other housing while barred from program-provide
This trial’s demonstration of the positive effect of housing, with or without an abstinence requirement, could be interpreted as favoring arguments for minimal or no barriers to housing entry during the rehabilitation of homeless persons. However, observed benefits accrued among persons who consented to participate in an addiction treatment trial, so it is unknown whether housing would confer similar benefits on addicted persons uninterested in treatment.
The current study is part of a series intended to examine the impact of applying contingency management (CM) interventions to substance use disorders. In a comparison of CM and CB treatment in polydrug abusers, Rawson and colleagues33 found that whereas CM interventions produced better short-term outcomes, CB treatment produced better long-term outcomes. However, when Higgins and colleagues34 conducted a trial that compared voucher reinforcements that were contingent or not contingent on abstinence, in a population with less severe addiction and rehabilitation problems than the current study, they observed greater abstinence at 15 months’ follow-up in the abstinence-cont
The most important limitation of this study concerns the missing data. We were unable to obtain sufficient assessments of abstinence beyond 6 months, and many scheduled urine tests during months 1 through 6 were missed by participants. High rates of missing data are a significant concern. However, 3 conventional analytic approaches for dealing with missing data yielded consistent results in group comparisons. Furthermore, we reported the results with the most conservative of the procedures (coding missed tests as drug-positive),
Provision of housing during day treatment of homeless substance abusers was associated with greater drug abstinence. This study has clear implications for treatment and housing of homeless substance abusers.
| Acknowledgments |
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The following individuals contributed substantial assistance: Jonathan Dunning, MA, Sonja Frison, PhD, Stefan Kertesz, MD, Cecelia McNamara, PhD, Max Michael, MD, Mary A. Plant, PhD, Stewart Usdan, PhD, and Catherine Ward, PhD.
Human Participant Protection All procedures and research reported here were reviewed, approved, and monitored by the University of Alabama at Birmingham institutional review board for Human Research.
| Footnotes |
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Contributors
J. B. Milby and J. E. Schumacher originated the study and supervised implementation.
Accepted for publication August 2, 2004.
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