Cost-effectiveness of assertive community treatment for homeless persons with severe mental illness. A F Lehman, L Dixon, J S Hoch, B Deforge, E Kernan and R Frank BJP 1999, 174:346-352. Access the most recent version at DOI: 10.1192/bjp.174.4.346
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B R I T I S H J O U R N A L O F P S Y C H I A T R Y ( 1 9 9 9 ) . 114. 1 4 6 - 1 1 2
Cost-effectiveness of assertive community treatment for homeless persons with severe
project did not specifically target highcost patients, generally the focus for ACT programmes.
mental illness ANTHONY F. LEHMAN, LISA DIXON. JEFFREY S. HOCH. BRUCE DEFORGE, ElMER KERNAN and RICHARD FRANK
Background Homelessness is a major public health problem among persons with severe mental illness (SMI).Costeffective programmes that address this problem are needed. Aims To evaluate the cost-effectiveness of an assertive community treatment (ACT) programme for these persons in Baltimore, Maryland. Methods A total of I52 homeless personswith SMI were randomly allocated to either ACTor usual services. Direct treatment costs and effectiveness, representedby days of stable housing, were assessed. Results Compared with usual care, ACT costs were significantly lower for mental health in-patient days and mental health emergency room care, and significantly higher for mental health outpatient visits and treatment for substance misuse. ACT patients spent 3 1 % more days in stable housing than those receiving usual care. ACTand usual services incurred $242 and $415 respectively in direct treatment costs per day ofstable housing,
an efficiency ratio of 0.58 in favour of ACT. Patterns ofcare and costs varied according to race.
Assertive community treatment (ACT) is one of the most studied service delivery models for persons with severe and persistent mental illnesses (Stein & Test, 1980; Burns & Santos, 1995; Mueser et al, 1998; Marshall & Lockwood, 1998). The rationale for this programme model is that by concentrating services for high-risk patients within a single multi-service team, continuity and coordination of care are enhanced, improving both the quality of care and its cost-effectiveness. At least 16 randomised trials comparing ACT with some usual-treatment alternative have consistently demonstrated relative advantages of ACT, especially in reducing in-patient treatment (Olfson, 1990; Burns & Santos, 1995; Mueser et al, 1998). ACT appears especially well suited to persons with severe mental illness (SMI), who have high rates of in-patient and crisis-based service utilisation. On the basis of these previous randomised trials, ACT has been identified as a necessary component of service systems for persons with schizophrenia (Rosenheck et al, 1995), and the National Alliance for the is promoting ACT in its advocacy of quality care (Flynn et al. 1997). Most studies of ACT have not fonnallv evaluated its cost-effectiveness, although it has been assumed that the consistent finding of reduced hospital utilisation translates into substantial cost savings (Olfson, 1990; & Santos, 1995: Mueser et al, 1998,. I, most that have the
costs of ACT relative to some alternative standard care, ACT has shown cost advanConclusion ACT provides a costtages related to reductions in in-patient care effective approach to reducing and enhanced functional status (earned wages). Increases in out-patient costs assohomelessness among persons with severe ciated with ACT substantially offset these and persistent mental illnesses. savings (Weisbrod et al, 1980; Wolff et al, ~ of ~ interest~hi^ work l 1995), yielding ~ overall cost ~ neutrality and ~ better outcomes. However, at least one was supported by a grant from the Center study found a substantial increase in overall for Mental Health Services, Rockville, costs. as well as better outcomes. associated Maryland. with .ACT (Chandler et al, 1996), but that
AIMS We previously reported on the effectiveness of ACT for homeless persons with severe and persistent mental illnesses when compared with usual community services (Lehman et al, 1997). We found that this ACT programme, relative to usual community services, reduced psychiatric inpatient days, emergency room visits, days homeless and days in jail. ACT increased out-patient visits and days of stable community housing. These differences were associated with improved quality of life and clinical outcomes. In this paper we address the question of costs: what are the direct treatment costs and cost-effectiveness of ACT versus usual services for achieving stable housing for homeless persons with SMI? This question is critical to health care payers (in this case, the state mental health and Medicaid authorities) and to service providers who may assume clinical responsibility and financial risk for the care of persons with SMI under publicly funded managed care. We focus on direct m a t ment costs because these are the costs of primary concern to health care payers and of central concern in current health policy debates. We chose housing status as the main effectiveness measure because this possesses established validity as a primary outcome for homeless persons with severe and persistent mental illnesses (Newman, 1992). Also, from the state's perspective, reducing homelessness is an important social benefit and a major political and social welfare priority. Homelessness among persons with mental illness is viewed by the state and its citizens as a failure of the public mental health care system and as a threat to public safety and commerce in major metropolitan areas. Hence, the logic of this experiment is that by providing coordinated, community-based care through the ACT programme, homeless persons with SMI will spend more days in stable community housing,~with savingsi realised by shifting ~ the patterns of care from higher cost crisis-oriented in-patient and emergency services to lowercost, on-going ambulatory services.
~
a51 r v n nvmtLtss r t n s v ~ W s
METHOD Design The study design and methods have been reported previously (Lehman et al, 1997) and will only be summarised here. This was a randomised trial comparing the ACT programme with the usual care available to homeless persons with SMI in Baltimore, Maryland. Study participants met entry criteria for both severe and persistent mental illness and homelessness. The mental illness criteria were based upon diagnosis, duration of illness, and level of disability, as defined in prior studies (Goldrnan et al, 1981; Schimar et a/, 1990; Lehman et al, 1994). Homelessness criteria were also based upon prior studies (Morrissey & Dennis, 1990) and emphasised 'literal homelessness' on the streets or in shelters. Subjects were recruited over the period March 1991 to September 1992. Project staff screened all persons acutely admitted to inner-city psychiatric hospitals as well as all referrals from agencies serving homeless persons in metropolitan Baltimore (primary health care agencies, shelters, rnissions and soup kitchens). After providing a complete description of the study to subjects, informed written consent was obtained. A total of 152 subjects out of 183 (83%) screened as eligible agreed to participate and entered the study. The sample characteristics included: 67% men; 72% African-Americans; mean age 3 7 years; mean time in education 11 years; 61.8% never married; 58% with schizophrenia or schizoaffective disorder, 20% with bipolar disorder, 8% with major depression, and 14% with another SMI; 71% comorbid for substance use disorders. A majority (74%) had been homeless for at least one year in total, and 34% had been homeless for four or more years in total.
Interventions The experimental condition was the use of an ACT team, based on the programme of assertive community treatment (PACT) model, first developed by Stein & Test (1980). Consistent with the model's philosophy, the ACT team defined its mission broadly to integrate assertive, communitybased clinical treatment with intensive case management and advocacy. The team's long-term commitment was to promote continuity of care, and the team was available 24 hours a day, every day. The ACT team consisted of 12 full-time-equivalent
staff, including a programme director with a master's degree in social work, a full-time psychiatrist as medical director, six clinical case managers (social workers, psychiatric nurses and rehabilitation counsellors), two consumer advocates, a secretaryreceptionist, a part-time family outreach worker from the Alliance for the Mentally I11 of Metropolitan Baltimore, and a parttime nurse practitioner to treat chronic medical problems. Each patient was assigned to a 'mini-team' consisting of a clinical case manager (whose case load was 10-12), an attending psychiatrist and a consumer advocate. However, the entire team worked together in decision-making, and each staff member was knowledgeable about most of the patients. Teamwork was fostered through daily sign-out rounds and twice-weekly treatment planning meetings. The ACT programme was implemented according to standard guidelines provided by PACT developers. After the first year of operation, a site visit by an ACT programme expert from Madison, Wisconsin confirmed the programme's adherence. As reported in more detail elsewhere, the ACT programme met criteria relating to community-based services, access, continuity of care, team approach and case management (Dixon et al, 1995). The clinical director was directly involved in patient care, and the psychiatrist was a full member of the team. The usual-care condition used as a comparison consisted of services usually available to homeless persons in Baltimore. The public mental health system in Baltimore encompasses seven community mental health centres operating under a non-profit-making, private local mental health authority, which was developed as part of the Robert Wood Johnson Foundation Program on Chronic Mental Illness (Goldrnan et al, 1994). Several community-based psychiatric in-patient and emergency facilities, including those affiliated with two major teaching institutions, provide acute in-patient and crisisoriented care. A variety of community agencies specifically focus on serving the homeless; for example, Health Care for the Homeless offers outreach, advocacy, case management, primary health care and walk-in mental health counselling, and some long-term out-patient mental health care. The goal of Health Care for the Homeless is to engage homeless persons in health care and to facilitate their transition to mainstream health care services. The
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homeless provider network also includes a number of privately run shelters, missions and soup kitchens.
Costs The cost-estimation strategy involved computing direct treatment costs for each patient across the one-year intervention period and then aggregating within intervention groups to compute costs per patient. Costs included both fee-for-service and budgeted services (all ACT services). The cost estimations followed this general equation: total costs (TC)=volume of services (S)x unit cost (UC). Volume of service We estimated service utilisation using a variety of data sources as recommended by Clark et a1 (1996). An independent research team conducted structured monthly client interviews to ascertain monthly service utilisation. Medicaid claims were obtained on all enrolled subjects during the study period. Client interview and Medicaid service utilisation data were available on all subjects. In addition, the ACT team kept highly accurate records on the nightly locations of all ACT patients. We took advantage of the latter to assess the validity of Medicaid claims and client self-reports relative to these ACT records, which were regarded as the 'gold standard' for estimating in-patient days. Missing values in client monthly self-reports were replaced by the mean of available data for that subject. The total proportion of services imputed in this manner was 17.8%. We found that client monthly self-reports of in-patient service utilisation were highly correlated with ACT team data (r=0.86), whereas Medicaid claims were not (r=0.18). In aggregate, ACT patients reported a total of 2262 hospital days compared with 2268 recorded in the ACT records, an aggregate error rate of less than 1%. This strongly supported the validity of client self-reports of in-patient days as the basis for in-patient service utilisation. We did not have comparable validation data for ambulatory service utilisation by ACT patients or for any service utilisation by comparison patients. However, we did find a low correlation between the Medicaid claims for out-patient services and client self-reports, similar to the findings for ACT patient in-patient costs as above, with Medicaid grossly under-reporting utilisation. Hence, the client monthly self-reports
L E H M A N E T AL
were used as the basis for volume-of-service counts.
Table I Mean (s.d.) costs per case
ACT
Treatment service type
Unit costs Unit costs (UC,) for the range of fee-forservice, non-ACT treatment services consumed by patients were developed using Medicaid cost-based reimbursement rates for ambulatory services, and in-patient cost rates established by Maryland Health Services Cost Review Commission (HSCRC). These unit costs are shown in Table 1. The psychiatric in-patient daily unit cost is an aggregated estimate derived from the HSCRC rates for the various metropolitan hospitals used by patients in the study and weighted according to the proportion of in-patient days that occurred in each hospital. The in-patient unit costs also include professional and ancillary service costs.
(Unit cost. 1994 US$)
Mean
s.d.
Mean
s.d.
Memal health Out-patient (ACT: $45.19 usual care: $El)* In-patient ($862) Emergency room ($200) Rehabilitation(550) S u h c e misuse Out-patient (ACT: $45.19 usual care: $81)' In-patient ($333) Emergency room ($200) Rehabilitation - out-patient ($40) Rehabilitation - in-patient ($72) General medicine
ACT budget costs
The total annual budget for the ACT programme was fixed, but the actual cost of caring for individuals varied substantially. Although the ACT cost per case could be computed by simply dividing the total ACT budget by the number of ACT cases, this approach obscures the variability in ACT costs per individual. An alternative approach was therefore used to separate ACT costs for individual patients into fixed and variable components. We assumed that the total ACT costs were distributed as 50% fixed costs (ACTF) and 50% variable costs (ACT,). Fixed ACT costs include standard overheads (space, vehicles, administration) as well as services not attributable to a specific patient, such as outreach, case-finding, and networking with other community providers. These activities were substantial for the ACT programme. As shown in Table 1, this fixed ACT cost per patient was estimated at $4122, computed as 50% of the total ACT budget divided by the number of ACT patients. The variable ACT cost for each patient was computed by multiplying the number of ACT services used by the unit cost for by the patient (S,) an ACT visit (UC,,). UC,, equals 50% of the ACT budget not attributed to fixed costs divided by the total number of ACT service units provided during the intervention year. As shown in Table 1, UC,, calculated thus was $45.19. Hence the variable ACT costs for an individual patient,
Out-patient (ACT: $45.19 usual care: $73)* In-patient ($1 137.59) Emergency room ($200)
Fixed ACT cost per case Total cost Black White All NA, not available; ACT, assertive community vervnent. *P
