Cost-Effectiveness of Tuberculosis Screening and Observed Preventive Therapy for Active Drug Injectors at a Syringe-Exchange Program

Abstract

This study examined whether costs associated with tuberculosis (TB) screening and directly observed preventive therapy (DOPT) among drug injectors attending a syringe exchange are justified by cases and costs of active TB cases prevented and examined the impact of monetary incentives to promote adherence on cost-effectiveness. We examined program costs and projected savings using observed adherence and prevalence rates and literature estimates of isoniazid (INH) preventive therapy efficacy, expected INH hepatoxicity rates, and TB treatment costs; we conducted sensitivity analyses for a range of INH effectiveness, chest X-ray (CXR) referral adherence, and different strategies regarding anergy among persons affected with human immunodeficiency virus (HIV). For 1,000 patients offered screening, incorporating real observed program adherence rates, the program would avert $179,934 in TB treatment costs, for a net savings of $123,081. Assuming a modest risk of TB among HIV-infected anergic persons, all strategies with regard to anergy were cost saving, and the strategy of not screening for anergy and not providing DOPT to HIV-infected anergic persons resulted in the greatest cost savings. If an incentive of $25 per person increased CXR adherence from the observed 31% to 50% or 100%, over a 5-year follow-up the net cost savings would increase to $170,054 and $414,856, respectively. In this model, TB screening and DOPT at a syringe exchange is a cost-effective intervention and is cost-saving compared to costs of treating active TB cases that would have occurred in the absence of the intervention. This model is useful in evaluating the cost impact of planned program refinements, which can then be tested. Monetary incentives for those referred for screening CXRs would be justified on a cost basis if they had even a modest beneficial impact on adherence.

Costs and Cost-effectiveness of Four Treatment Regimens for Latent Tuberculosis Infection

“…Nonetheless, this regimen may be useful in instances where nonadherence to self-administered therapy is likely and rifamycins are contraindicated, such as in patients taking boosted HIV protease inhibitors. Additionally, two studies looking at the cost-effectiveness of observed isoniazid in drug users found it to be cost-saving compared with no therapy (17,18). In both instances, however, the costs of DOT were very low because the procedures were performed by clinic staff already seeing the patients for other purposes, and no shorter regimens were compared.…”

Hospital- Versus Community–Based Syringe Exchange: A Randomized Controlled Trial

“…Injection drug users (IDUs) use public emergency departments as a regular source of care; this setting would afford the opportunity to identify active IDUs and engage them in HIV risk reduction efforts. Furthermore, because referral to off-site services impedes service delivery to IDUs (Umbricht-Schneiter, Ginn, Pabst, & Bigelow, 1994), syringe exchange services on site in health care facilities may expedite the delivery of less costly services (Perlman et al, 2001).…”

Impact of Monetary Incentives on Adherence to Referral for Screening Chest X-rays After Syringe Exchange-Based Tuberculin Skin Testing

“…5,11,12 Institutional review board approved consent was obtained from all study participants. At first contact, participants were offered tuberculin skin testing, underwent a staff-administered interview, and were offered human immunodeficiency virus (HIV) counseling and testing.…”

“…5 Only 34% of injection drug users (IDUs) adhered to referral for screening CXRs. 5,11 Incomplete adherence to this step of TB screening limits the ability to identify appropriate candidates for preventive therapy. Nonetheless, even with the observed limited adherence to this step of TB screening, we found that overall TB screening and observed treatment of LTBI performed at an SEP remained both a cost-effective and a potentially costsaving intervention.…”

“…11 If an incentive of $25 were able to increase the observed rate of CXR referral adherence from the observed 34% to even 50%, significant additional cost savings would be realized.…”