|Equation||(# participants hospitalized) x (% participants get assistance solely because of the program) x (% participants hospitalized as a result of a mental illness) x (% decrease in hospitalizations) x (# QALY increase) x ($ QALY)|
|Explanation||This metric estimates the impact of stable housing on decreased hospitalizations as a result of mental illness, estimated in terms of quality-adjusted life years (QALY).
Number of participants hospitalized during the year: Reported by program.
Percent of these adults receiving treatment due to the program: [0.52], in absence of program relevant data, we use the counterfactual used for homelessness reduction interventions. That is, for programs serving individuals at imminent risk of homelessness (e.g. individuals coming from shelters, or with eviction notices and no feasible housing alternative), we assume a 100% rate of effectiveness. To this number, we subtract the percentage of homeless individuals in the Twin Cities metropolitan area who are on a waiting list for any public housing, Section 8 housing, or some other type of housing that offers financial assistance as a counterfactual [48%] (Wilder Research, 2016).
Percentage of participants hospitalized as a result of a mental illness: [80%], we estimate that 80 percent of those who are housed in supportive housing and who avoided hospitalization would have been hospitalized due to mental illness or substance abuse conditions based on research indicating that approximately 80 percent of homeless people have primary or secondary mental illness/substance abuse conditions (Salit, Kuhn, Hartz, Vu & Mosso, 1998).
Percentage decrease in hospitalizations: [30%], decrease in hospitalizations for people receiving supportive housing (Culhane, Metreaux & Hadley, 2001; Martinez & Burt, 2006; Sadowski, Kee, VanderWeele & Buchanan, 2009). If research studies find a range of results, we will apply the lowest estimate.
QALY increase: [0.33], value of avoiding hospitalization for mental illness/substance abuse conditions at 0.33 QALY, by averaging the QALY values for the avoidance of depression, estimated at 0.30 QALY (especially Frank, McGuire, Normand & Goldman, 1999; Schoenbaum, Sherbourne & Wells, 2005), and avoiding relapse of schizophrenia, estimated at 0.36 QALY (Davies et al., 2008).
$ value per QALY: [$50,000].
Benefits are then discounted to present value based on the average age of participation to life expectancy.
|References||Culhane, D. P., Metreaux, S. & Hadley, T. (2001). The impact of supportive housing for homeless people with severe mental illness on the utilization of the public health, correcting, and emergency shelter systems: The New York-New York Initiative. Washington, DC: Fannie Mae Foundation.
Davies, A., Vardeva, K., Loze, J., L’Italien, G., Sennfalt, K. & van Baardewijk, M. (2008). Cost-effectiveness of atypical antipsychotics of the management of schizophrenia in the UK. Current Medical Research and Opinion, 24(11), 3275–3285.
Frank, R., McGuire, T., Normand, S. & Goldman, H. (1999). The value of mental health care at the system level: The case of treating depression. Health Affairs, 18(5), 71–88.
Martinez, T. E. & Burt, M. (2006). Impact of permanent supportive housing on the use of acute care health services by homeless adults. Psychiatric Services (Washington, D.C.), 57(7), 992–999