summarizes sample screening, accrual and retention. Our original design called for participants to be recruited during their inpatient stay at a state-operated psychiatric hospital located in the NYC metropolitan area. However, before recruitment began, policy changes in the mental health system led most patients with housing difficulties to be discharged to transitional residences located on the grounds of this hospital and a second nearby hospital. We therefore altered our design to recruit participants at these two residences rather than on the inpatient wards. Persons were considered eligible if they met the following criteria: 1) currently living in one of the two designated transitional residences following hospitalization during the four-year recruitment period (2002–2006) and discharged from the residence before the end of this period; 2) a lifetime DSM-IV diagnosis of a psychotic disorder (codes 295.xx, 296.xx and 298.9); 3) homeless at the index hospitalization or an episode of homelessness within eighteen months preceding this admission; and 4) spent their first night after leaving the transitional residence in New York City in a place other than a jail or a hospital (so that all subjects were at equal risk of homelessness during the observation period and those assigned to the CTI condition would be accessible to the CTI worker). We excluded those who were unable to provide informed consent for the screening interview or did not speak sufficient English to participate. We also excluded those who did not stay more than three weeknights in the transitional residence or whose employment schedule made them unavailable to project staff during regular work hours.
Research staff approached individuals identified by clinical staff as having a plan for discharge to New York City. After obtaining written consent for the screening interview, research staff determined whether they had been homeless (defined as staying overnight in a shelter, on the streets, in a park, on a subway train, or in any other public space) during the eighteen months prior to hospitalization. Those who met this criterion were then provided with the study description and their written informed consent for participation in the trial was obtained. Eligible participants completed a baseline interview, including the Structured Clinical Interview for DSM-IV (SCID) (
12); this was used to verify that the participant met our diagnostic eligibility criterion. Those not meeting this criterion were excluded at this point.
Randomization
Participants were randomized independently by gender and by diagnosis of lifetime substance use disorder. To reduce variation on key factors, we randomized individuals in these four strata in permuted blocks of randomly varying size. The names of eligible participants and their respective randomization stratum were given to an administrator who did not need to be blind to treatment status. Working from a list produced by our statistician of identification numbers with associated random treatment condition assignments, she assigned each participant the next available identification number within the designated stratum. For participants assigned to the CTI condition, she then notified the CTI clinical supervisor who added the participant to the CTI caseload. 32 randomized participants were subsequently dropped from the study because they were never discharged from the transitional residence during the recruitment period or because their first post-discharge night was spent either outside of New York City, in jail, or in a hospital. This procedure was approved a priori by the study’s biostatistician.
Assessments
The Personal History Form, employed extensively in our earlier research with this population, was used at baseline to measure demographic characteristics and personal history, including prior use of treatment services, residential history, and previous homeless episodes (
10). Following discharge from the transitional residence, participants were interviewed every six weeks for eighteen months in order to document where they had spent each night during the respective follow-up period. These assessments were carried out by trained interviewers blind to the participant’s group assignment. In cases in which a participant had missed an interview, the interviewer documented where the participant had spent each night since the last completed assessment. We chose to collect data at six-week intervals for two reasons. First, we sought to minimize reporting inaccuracies on the part of study participants with respect to their housing experience. Furthermore, our previous experience with this population suggests that more frequent contact between research staff and participants reduces the likelihood of participants being lost to follow up. In some instances when participants could not be directly interviewed, we gathered residential data from a family member, caseworker, or another of the participant’s close associates who we had been granted permission to contact. We have reported previously on a test-retest study demonstrating that homelessness could be assessed with high reliability (
kappa=.93) using this approach (
10). Participants received $20 for each of the baseline, nine and 18-month interviews and $10 for each six-week interview they completed.
Interventions
While living in the transitional residence, all participants received basic discharge planning services and access to psychiatric treatment. After discharge, participants in both conditions received a range of “usual” community-based services depending on the individual’s needs, preferences and living situation. These services usually included various types of case management and clinical treatment. 12 participants (8%) were assigned to mandatory outpatient treatment and/or assertive community treatment programs.
In addition to the services noted above, participants randomly assigned to the experimental condition received nine months of CTI following discharge from the transitional residence. Those assigned to the control condition received usual services only. Post-discharge housing arrangements were typically coordinated by discharge planning staff located at the transitional residence. These arrangements ranged from community residences and other structured programs to supported apartments and independent housing, either alone or with family members. Neither CTI workers nor research staff were involved in determining the initial housing arrangement for individuals in either condition. Some individuals left the transitional residence “against medical advice” and returned to shelters or the streets but were nonetheless retained in the study.
CTI is described in detail in our previous publications (
13,
14). In brief, it is a nine-month case management intervention delivered in three phases, each of which lasts approximately three months (see ). Phase one--
transition to the community--focuses on providing intensive support and assessing the resources that exist for the transition of care to community providers. Ideally, the CTI worker will have already begun to engage the client in a working relationship before he or she moves into the community. This is important because the worker will build on this relationship to effectively support the client following discharge from the institution. The CTI worker generally makes detailed arrangements in only the handful of areas seen as most critical for community survival of that individual. Phase two—
try out-- is devoted to testing and adjusting the systems of support that were developed during phase one. By now, community providers will have assumed primary responsibility for delivering support and services, and the CTI worker can focus on assessing the degree to which this support system is functioning as planned. In this phase, the worker will intervene only when modification in the system is needed or when a crisis occurs. Phase three—
transfer of care-- focuses on completing the transfer of responsibility to community resources that will provide long-term support. One way in which CTI differs from services typically available during transitional periods is that the transfer of care process is not abrupt; instead, it represents the culmination of work occurring over the full nine months.
| Table 1Phases and Activities of Critical Time Intervention |
CTI was delivered by three workers trained by several of the model developers. Two were bachelors level employees of the NYS Office of Mental Health re-assigned to this project from their regular duties. The third worker, who also performed some supervisory activities, was a more experienced worker who had previously delivered CTI in an earlier trial. Weekly supervision was carried out by clinically trained staff experienced in the model.
Study attrition and treatment receipt
summarizes the flow of participants from screening through follow-up. Of the 150 participants randomized, 77 participants (51%) were assigned to the experimental condition (CTI) and 73 (49%) were assigned to the control condition (usual care). 58 participants (75%) assigned to the experimental condition completed the eighteen month follow-up period, while 59 participants (80%) assigned to the control condition completed the full follow-up period. Complete follow-up data were obtained for significantly more males than females (85% of males vs. 58% of females, (chi square 12.7, df 1, p=.001). Those with a substance dependence diagnosis were also more likely to have complete follow-up (91% of substance dependent vs. 61% of non-substance dependent, chi square 18.9, df 1, p<.001). There were no other group differences in loss to follow-up that were related to baseline characteristics, including prior homelessness.
Some participants assigned to the experimental condition did not receive all components of the intervention. In particular, a key ingredient of the CTI model is that post-discharge services are provided by a worker who has established a relationship with the client before he or she is discharged from the institution to the community. Workers were instructed to develop this relationship via multiple face-to-face contacts with the participant during the pre-discharge period. In our previous work, we have established a threshold of at least three such pre-discharge contacts as minimally sufficient for this purpose (
15). In the current study, 42 participants (56%) received three or more such contacts while 35 (44%) received two or fewer contacts. The failure to deliver the desired number of pre-discharge contacts was most often the result of limited time between participant randomization and discharge from the transitional residence. As noted earlier, our original plan was to recruit participants during their inpatient stay where delivering multiple pre-discharge contacts would not have presented a problem. Instead, we recruited in the transitional residences (in response to policy changes described above) where time to make contact with participants was limited by a variety of factors including significantly greater unpredictability in participants’ discharge dates.
Definition of primary outcome
We defined as our primary outcome a dichotomous measure of homelessness during the last three follow-up intervals (18 weeks) of the study. Since the primary goal of CTI is to produce a long-lasting effect on homelessness risk, the key test of its efficacy is whether the risk of homelessness is reduced at the end of the observation period. We chose the final three intervals because we felt that the final six-week observation interval itself was too short to generate a stable estimate of the treatment effect. Although we also measured the actual number of nights homeless reported by participants during each follow-up interval, the highly skewed distribution of homeless nights we anticipated (and observed) led us to use the dichotomous measure as our primary endpoint.
Loss to Follow-Up
While the proportion of the sample for whom we were unable to obtain complete follow data was low relative to other studies, it was not insubstantial. In order to verify the robustness of our findings, we carried out a multiple imputation procedure employing five imputations and repeated the analysis. Our findings remained virtually unchanged.
Statistical analysis
Our primary analysis was an intent-to-treat (ITT) comparison testing whether there was a group-level difference between participants assigned to the two groups on risk of homelessness during the last three follow-up intervals of the study. This analysis was carried out using logistic regression adjusting for baseline homelessness (number of homeless nights during the three month period preceding the index hospitalization). As noted above, we elected to use a dichotomous measure of homelessness (ever versus never homeless in the last three intervals) as our primary endpoint because the distribution of homeless nights was highly skewed. We chose not to employ survival analysis because such models are best suited for questions in which the primary interest concerns the length of time to the occurrence of an event, and our main interest was whether the CTI and usual services groups differed at the end of observation period.
We also conducted several secondary analyses. First, we tested whether there was a group-level difference between participants assigned to the two groups on total number of homeless nights during the final three intervals. We used a Poisson regression model, adjusting for baseline homelessness.
Second, we performed an as-treated analysis in order to obtain an unbiased estimate of receipt of a version of the intervention that included three or more pre-discharge contacts with the worker. This analysis used the same outcome as in our primary ITT analysis (i.e. ever versus never homeless in last three intervals). The analysis was carried out via a two-stage instrumental variables regression in which assignment to condition was the instrument and receipt of the intervention including three or more pre-discharge contacts with the worker was the treatment indicator (
16). Again we adjusted for baseline homelessness.
Third, we examined homelessness over the full 18-month follow-up period. Using logistic regression, adjusting for baseline homelessness, we first compared the two groups with respect to risk of homelessness (ever versus never homeless) over 18 months. Using Poisson regression, adjusting for baseline homelessness, we then compared the two groups with respect to number of nights homeless over 18 months.
The publisher's final edited version of this article is available at 
