Offering STIRR services in four test sites cost $399 more per client than did education and referral to offsite testing but resulted in improvements in hepatitis and HIV testing and hepatitis vaccination among persons with serious mental illness and a co-occurring substance use disorder (20
). These results suggest that during the first year of operation a full-time STIRR program may cost around $482,000 and may result in 683 additional at-risk persons tested for hepatitis C, 621 additional persons tested for hepatitis B, 133 additional persons tested for HIV, and 859 persons vaccinated for hepatitis A/B. Evidence from past research suggests that STIRR may achieve acceptable levels of cost-effectiveness provided that STIRR services are targeted to sufficiently high-risk populations and that a program sustains a sufficient volume of clients (21
STIRR services cost slightly less and achieved a higher rate of hepatitis B vaccination in comparison to a similar nurse case management intervention for vaccinating homeless adults (6
). That intervention cost $432 per person ($10 more than STIRR), achieved a 68% hepatitis A/B vaccination rate at 6 months compared to 78% in STIRR, and was deemed cost-saving in a decision analysis (20
). Risk levels among persons with serious mental illness and co-occurring substance use disorder are similar to those for other “high risk” groups (23
). Future hepatitis-related medical care costs are likely to be high in this population. Published prevalence estimates (3
) suggest that 8.4-16.9% of these persons may develop chronic hepatitis C (i.e., a persistence of hepatitis C RNA in the blood for six months or more). Discounted lifetime treatment costs per person treated for chronic hepatitis C are estimated to exceed $100,000 (32
). Thus, expected hepatitis C costs could be as much as $8.4-16.9 million for every 1000 at-risk persons. STIRR services would consequently be cost-neutral if they reduce costs by only 2.4-4.8%.
Although it is unknown whether STIRR would produce this level of savings, decision analyses indicate the prospect of substantial savings (21
). Besides future savings resulting from vaccination and Hepatitis C treatment benefit, additional savings might accrue from STIRR’s other clinical effects, which include reduced alcohol and illicit drug use and increased knowledge of risk-reduction when sharing needles and engaging in other risky behaviors (20
). Finally, recent advances in hepatitis C treatment and discoveries regarding the clinical benefits of early entry into HIV treatment may improve the savings from STIRR and other prevention programs. Two novel medications recently approved for use in hepatitis C treatment—boceprevir and telaprevir—have been shown to be more efficacious than prior medications (33
), and early treatment for HIV has been shown to reduce HIV transmissions and improve clinical outcomes among people who are HIV positive (36
In relation to dissemination, one of the advantages of the STIRR model is that the STIRR team is designed to have little impact on direct or indirect costs to the host organization (5
). Nevertheless, new dedicated financing would be needed to implement and sustain STIRR programs in a city, county, or state system. Managed care organizations that cover somatic care services for STIRR’s target population may be willing to finance STIRR services, as these organizations are likely to incur the future health care costs resulting from hepatitis and HIV-related morbidity, especially when care is financed using a population capitation rate. Conversely, managed behavioral healthcare organizations may have little financial incentive to provide STIRR services, unless the same managed care entity is financially at risk for both mental health and somatic care.
In any implementation of STIRR programs, several factors may cause average costs and client outcomes to deviate from estimates presented in this study. First, the number of clients seen by the STIRR nurse in a given period of time could be more or less than was estimated. The study’s cost estimates imply that the STIRR nurse completes 1140 encounters per year. A usual care implementation could achieve higher client volumes though routinization of the STIRR schedule at clinics, outreach to potential clients, and integration of STIRR services within clinics’ usual care processes. However, inefficiencies due to care coordination problems or poor planning could result in lower volumes and higher costs per person who receives vaccination and/or blood testing. Over time, the proportion of STIRR clients receiving hepatitis A/B vaccinations would also depend on the overall number of unvaccinated people in a target population. This number could either increase or decrease depending on the balance between the number of unvaccinated high-risk persons entering the target population, the number of hepatitis vaccinations given by STIRR and other programs, and attrition. Second, STIRR programs could incur greater-than-estimated or less-than-estimated administrative expenses for bookkeeping, managing supplies, regulatory reporting, patient outreach and payment of invoices. Expenses of $50 per participant ($5231 total) were incurred for training the STIRR nurse and coordinator and for orienting collaborating providers to the model. Over time, these expenses would be distributed over an increasing number of clients. However, there could be additional training expenses due to staff turnover and changes in medical practice requiring additional education. Finally, although the STIRR nurse would likely serve multiple clinics on a rotating schedule, we did not explicitly include travel costs in our estimates. Travel costs were subsumed in the nurse’s salary, because the nurse was not reimbursed for travel to study sites.
The finding that STIRR services cost an additional $3630 per person tested for HIV is attributable to the lower level of unmet need for HIV testing reported by participants. Only 21 (of 105) STIRR participants reported that they had not been tested for HIV in the 6 months prior to the study baseline. This pattern, which has been identified in at least one other sample (4
), suggests that many persons with serious mental illness either do not receive hepatitis tests when they are tested for HIV, or they underreport hepatitis testing and/or overreport HIV testing. To the extent that persons in this population already are regularly tested for HIV, co-testing for hepatitis at HIV testing sites would improve hepatitis detection and add only approximately $65 in costs.
A limitation of this study is that the primary measures of clinical outcome (testing and vaccination) could have been unreliably reported by participants. To check their validity, self-reported data were compared to the research study’s internal records of vaccinations and laboratory invoices for participants in the STIRR condition. The two independent sources produced nearly identical rates. Another limitation is the unavailability of information about future costs and benefits of hepatitis C treatment in persons with serious mental illness and co-occurring substance use disorder. Although follow-up medical care for chronic hepatitis C is considered cost-effective (23
), some medical care providers have reservations about treating people with serious mental illness (37
), partly because of the adverse psychological side effects of interferon. Finally, idiosyncratic features of the sample—predominantly low-income African American patients receiving mental health services at four programs in one urban area—could either worsen or improve the cost-effectiveness of STIRR services.