Accuracy Of Tuberculin Skin Test Research Articles

Novel health system strategies for tuberculin skin test-guided Isoniazid preventive therapy

Abstract Background Global TB elimination demands a scale-up of Isoniazid preventive therapy (IPT) but tuberculin skin test (TST)-guided IPT poses great logistical and human resource challenges. Objectives Performance of TST self-reading by patients and fast-track TST reading by trained low cadre health care workers (task-shifting) was compared to formal TST reading by high cadre staff in a cohort of 278 South African adults living with HIV. Health economic impact of these novel strategies was assessed from a provider and societal perspective and simulations were performed for 5 other countries (USA, Germany, Brazil, India, Russia) to evaluate generalizability. In addition, accuracy of TST at antiretroviral treatment (ART) initiation was assessed by a repeat TST 6 and 12 month later. Results TST self-reading was highly accurate, with 89% sensitivity (95% CI 80, 95) and 100% specificity (95% CI 97,100) for detecting presence/absence of any induration. Agreement in TST reading between low and high cadre health care workers was very high (kappa 0.97). Compared to standard of care, a combined fast-track, task-shifting and self-reading strategy reduced TST reading costs in South Africa from a patient perspective by 81% and from a provider perspective by 92%. In all 5 countries simulated, TST reading cost was reduced by ≥ 78 % from a provider perspective. Repeat testing at 6 and 12 months showed high (31%, 95% CI 23, 40) TST conversion during the first 12 months of ART. Conclusions Empiric IPT for all people living with HIV followed by TST assessment after 6 or 12 months to identify those in need for lifelong IPT could increase the effectiveness of IPT programs. TST self-reading to reduce the number of patients that need to return for TST reading (to only those patients with self-determined presence of any induration) together with fast-tracking and task-shifting of TST reading could increase cost-effectiveness and reduce patient costs associated with IPT programs. Key messages Novel strategies are essential to control TB. Task-shifting, fast-tracking and patient TST self-reading empower patients and HCWs; optimal TST timing can increase cost-effectiveness of IPT programs.

Interferon-\u03b3 release assay as a sensitive diagnostic tool of latent tuberculosis infection in patients with HIV: a cross-sectional study

BackgroundIn developing countries, tuberculosis (TB) is a major public health problem and the leading cause of death among patients with HIV (Human Immunodeficiency Virus). Until 2001, the tuberculin skin test (TST) was the only available tool for the diagnosis of latent tuberculosis infection (LTBI), but false-negative TST results are frequently reported. Recently, the interferon-γ (IFN-γ) release assay (IGRA) has gained ground because it can detect the IFN-γ secreted by circulating lymphocytes T cells when stimulated by specific TB antigens. However, the role of IGRA in the diagnosis of LTBI in HIV-infected patients has not been well established.MethodsThis cross-sectional study compared the accuracy of TST (performed by the Mantoux method) and IGRA (QuantiFERON-TB Gold In-Tube, Cellestis, Carnegie, Australia) on the diagnosis of LTBI among patients with HIV. LTBI is defined by LTBI risk and at least one positive test (TST or IGRA), without clinical evidence of active TB. We also assessed the accuracy of TST and IGRA among HIV patients with high and low risk for LTBI.ResultsAmong 90 HIV patients, 80 met the study criteria for LTBI, fifty-nine (73.7%) patients were TST positive, 21 (26.2%) were negative, whereas 75 patients (93.7%) were IGRA positive, and five (6.2%) were negative. TST showed poor agreement with the diagnosis of LTBI (Kappa: 0.384), while IGRA demonstrated good agreement (Kappa: 0.769). Among 69 patients with high risk and 21 with low risk for LTBI, TST was positive in 48 (69.5%) and 11 (52.4%), while IGRA was positive in 68 (98.5%) and 7 (33.3%) patients, respectively. There were no association between TST and the level of risk (P = 0,191). Conversely, we observed a strong association between the IGRA and risk for LTBI (p < 0.001).ConclusionsCompared to TST, IGRA positivity is consistent with the risk of TB infection and seems to be a better diagnostic tool for LTBI in HIV-infected patients.

Is the tuberculin skin test alone accurate in moderate-to-severe BCG vaccinated patients with inflammatory bowel disease treated with immunosuppressives to test for latent tuberculosis?

Background and Aims: There are few data available on effect of immunomodulator/biological therapy on the accuracy of tuberculin skin test (TST, Mantoux skin test) and interferon-gamma release assay (IGRA) in BCG vaccinated immunosuppressed IBD patients. Our aim was to define the accuracy of the TST and IGRA tests in a BCG vaccinated referral IBD cohort treated with immunosuppressives and/or biologicals.