Using IGRA in the diagnosis of tuberculosis or latent tuberculosis infection in HIV-positive persons

Publikation: Bidrag til tidsskriftKonferenceartikelForskningfagfællebedømt

Persons with HIV and LTBI are at very high risk of developing active TB. The CD4 count drops in persons during the natural course of HIV/AIDS and at the same time the risk of TB increases. It is clear that there is a TB protective effect when HIV patients are placed on highly active antiretroviral treatment (HAART) and thereby restore immunity. Diagnosing HIV patients with active TB can be a challenge. To diagnose patients with active TB, the test should have high sensitivity, high specificity and be able to discriminate between active and latent TB. There are many studies assessing IGRA in HIV-positive individuals, and our learning curve is going up with new knowledge and circumstantial evidence. There is clearly an effect on the performance of the IGRA test when persons with active TB are co-infected with HIV. Studies looking at the performance of QFT-GIT in HIV-positive/negative TB patients show significantly lower positivity rates in HIV-positive patients. The clinical use of IGRA for the diagnosis of active TB in HIV-positives in high endemic regions may be limited for several reasons, and it is not always recommended to use IGRA in all cases of clinical suspicion. Arguments against using IGRA in HIV-positive populations are: 1) the reduced sensitivity in HIV-positive individuals; 2) more indeterminate results; 3) an inverse relation between indeterminate/false-negative and CD4 cell count; 4) IGRAs are not a general rule-out test (35-39% false-negative); and 5) the IGRA does not discriminate between active TB and LTBI. Key arguments for using IGRAs in HIV-infected individuals are: 1) superior sensitivity in HIV-positive patients compared to the TST; 2) patients with a CD4 >350 cells/mu l have performance comparable to HIV-negative patients; and 3) one third of the severely immunocompromised patients do have a positive IGRA response. There are, however, important unresolved issues that require further studies. What is the added value of using IGRAs in a clinical setting to correctly diagnose patients and prevent new cases? Are the differences between QFT-GIT and T-SPOT clinically relevant? Will we ever have a test that can discriminate between active and latent TB? Do we know enough about the impact of HIV on IGRA performance? Will we be able to improve the sensitivity in persons who are immunocompromised using individual cut-off points and additional biomarkers? Dr Ravn presented and asked for feedback on a proposal of how to use IGRAs in HIV-infected persons
TidsskriftInternational Journal of Tuberculosis and Lung Disease
Udgave nummer6
Sider (fra-til)S36-S38
StatusUdgivet - 2010

ID: 34055180