Cost effectiveness of testing HIV infected individuals for TB in a low TB/HIV setting.

OBJECTIVES: Guidelines recommend routine testing for latent TB infection (LTBI) in people living with HIV. However there are few cost-effectiveness studies to justify this in contemporary high resource, low TB/HIV incidence settings. We sought to assess the uptake, yield and cost-effectiveness of testing for latent and active TB. METHODS: Adults attending an ambulatory HIV clinic in London, UK were prospectively recruited by stratified selection and tested for TB infection using symptom questionnaires, chest radiograph (CXR), tuberculin skin test (TST), T-Spot.TB and induced sputum. From this, 30 testing strategies were compared in a cost-effectiveness model including probabilistic sensitivity analysis using Monte Carlo simulation. RESULTS: 219 subjects were assessed; 95% were using antiretroviral therapy (ART). Smear negative, culture positive TB was present in 0.9% asymptomatic subjects, LTBI in 9%. Only strategies testing those from subSaharan Africa with a TST or interferon gamma release assay (IGRA) with or without CXR, or testing those from countries with a TB incidence of >40/100,000 with TST alone were cost-effective using a £30,000/QALY threshold. CONCLUSIONS: Cost-effectiveness analysis in an adult HIV cohort with high ART usage suggests there is limited benefit beyond routine testing for latent TB in people from high and possibly medium TB incidence settings.

Decreasing cost effectiveness of testing for latent TB in HIV in a low TB incidence area.

Testing for latent tuberculosis infection (LTBI) in HIV-infected persons in low tuberculosis (TB) incidence areas is often recommended. Using contemporary, clinical data, we report the yield and cost-effectiveness of testing all HIV attendees, two current UK strategies and no LTBI testing. Economic modelling was performed utilising 10-year follow up data from a large HIV clinical cohort. Outcomes were numbers of cases of active TB and incremental cost per quality-adjusted life year (QALY) gained. Between 2000 and 2010, 256 people were treated for TB/HIV co-infection. 72 (28%) occurred ≥3 months after HIV diagnosis and may have been prevented by LTBI testing. Between 2000 and 2005, the incremental cost per QALY gained for the British HIV Association (BHIVA) and UK National Institute of Care Excellence (NICE) strategies, and testing all clinic attendees was €6270, €6998 and €33,473, respectively. These rose to €9332, €32,564 and €74,067, respectively, between 2005 and 2010. Probabilistic sensitivity analysis suggested that at a threshold of €24,000 per additional QALY, the most cost-effective strategies would be NICE or testing all in 2000-2005 and BHIVA during 2005-2010. Both UK testing regimens missed cases but are cost-effective compared with no testing. Using recent data, they all became more expensive, suggesting that alternative or more targeted TB testing strategies must be considered.

Yield and cost effectiveness of mycobacterial infection detection using a simple IGRA-based protocol in UK subjects with inflammatory bowel disease suitable for anti-TNFα therapy.

BACKGROUND AND AIMS: Testing for LTBI is recommended prior to anti-TNFα agents. This includes an assessment of TB risk factors, chest radiograph, and interferon-gamma release assay alone or with concurrent Tuberculin skin testing. Here we review our experience and cost-effectiveness of using T-SPOT.TB IGRA to detect mycobacterial infection in patients with IBD suitable for anti-TNFα therapy. METHODS: This was a single-centre, retrospective review and economic evaluation (compared to British Thoracic Society guidance) of 125 adult IBD patients (90 anti-TNFα naïve, 35 established on anti-TNFα) tested for LTBI using T-SPOT.TB IGRA. RESULTS: All subjects had normal chest radiographs and no clinical evidence for TB. 109 (87%) were BCG vaccinated. 27 (22%) of all patients tested were not using immunomodulation at the time of testing. 66 (53%) were taking thiopurines, 22 (18%)corticosteroids, and 35 (28%) anti-TNFα agents. One hundred twenty two (98%) had a negative IGRA result, two (2%) had positive results, and one (1%) had an indeterminate IGRA. A strategy using IGRA to guide TB preventative treatment produced cost savings of £10.79 per person compared to the BTS guidance. Eighty eight percent of the anti-TNFα naïve group have subsequently received treatment with either infliximab or adalimumab (median follow-up of 24 months, IQR 18-30) with no cases of TB disease occurring. CONCLUSIONS: The use of a simple screening protocol for LTBI incorporating T-SPOT.TB IGRA in place of TST in a largely BCG vaccinated population, many using immunomodulatory agents, appears to work well and is a cost-effective strategy in our IBD service.