Sensitivity of IFN-gamma release assay to detect latent tuberculosis infection is retained in HIV-infected patients but dependent on HIV/AIDS progression.

BACKGROUND: Detection and treatment of latent TB infection (LTBI) in HIV infected individuals is strongly recommended to decrease morbidity and mortality in countries with high levels of HIV. OBJECTIVE: To assess the validity of a newly developed in-house ELISPOT interferon-gamma release assay (IGRA) for the detection of LTBI amongst HIV infected individuals, in comparison with the Tuberculin Skin Test (TST). METHODOLOGY/PRINCIPAL FINDINGS: ESAT6/CFP10 (EC) ELISPOT assays were performed, together with a TST, in 285 HIV infected individuals recruited in HIV clinics in Dakar, Senegal, who had no signs of active TB at time of enrolment. Thirty eight of the subjects (13.3%) failed to respond to PHA stimulation and were excluded from the analysis. In the 247 remaining patients, response to PHA did not vary according to CD4 cell count categories (p = 0.51). EC ELISPOT was positive in 125 (50.6%) subjects, while 53 (21.5%) had a positive TST. Concordance between EC ELISPOT and TST was observed in 151 patients (61.1%) (kappa = 0.23). The proportion of subjects with a positive response to the EC ELISPOT assay decreased with declining CD4 counts (p trend = 0.001), but were consistently higher than the proportion of TST responders. In multivariate analysis, the risk of being EC-ELISPOT positive in HIV infected individuals was associated with age, CD4 count and HIV-1 strain. CONCLUSION: Our study indicates that IGRAs using M. tuberculosis specific antigens are likely to retain their validity for the diagnosis of LTBI among HIV positive individuals, but may be impaired by T-cell anergy in severely immuno-suppressed individuals.

Effectiveness of a strategy to improve adherence to tuberculosis treatment in a resource-poor setting: a cluster randomized controlled trial.

CONTEXT: Poor adherence to treatment remains a major obstacle to efficient tuberculosis (TB) control in developing countries. Innovative strategies to improve access and adherence to treatment are needed. OBJECTIVES: To assess the effectiveness of a contextualized intervention strategy aimed at improving patients' adherence to treatment and to evaluate its impact on TB control in a resource-poor country in Africa with prevalent TB infection. DESIGN, SETTING, AND PATIENTS: A cluster randomized controlled trial, conducted between June 2003 and January 2005, at 16 government district health centers in Senegal. Patients older than 15 years with newly diagnosed sputum smear-positive pulmonary TB were randomly assigned to the intervention or control group. INTERVENTION: The intervention strategy included reinforced counseling through improved communication between health personnel and patients, decentralization of treatment, choice of directly observed therapy (DOT) supporter by the patient, and reinforcement of supervision activities. In the control group, the usual TB control program procedures remained unchanged. MAIN OUTCOME MEASURE: Proportion of patients successfully completing the 8-month course of treatment and the proportion of patients defaulting from treatment. RESULTS: A total of 1522 patients were recruited into the study. Treatment was successful for 682 (88%) of 778 patients recruited in the intervention group, and for 563 (76%) of 744 patients recruited in the control group (adjusted risk ratio [RR], 1.18; 95% confidence interval [CI], 1.03-1.34). The proportion of patients defaulting was reduced in the intervention group to 5.5% (n = 43) compared with 16.8% (n = 125) in the control group (adjusted RR, 0.43; 95% CI, 0.21-0.89). CONCLUSION: The intervention package based on improved patients counseling and communication, decentralization of treatment, patient choice of DOT supporter, and reinforcement of supervision activities led to improvement in patient outcomes compared with the usual TB control procedures. This approach may be generalized in the context of TB control programs in resource-poor countries. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00412009.