The diagnostic performance of TB-IGRA on HIV infected patients with active tuberculosis is associated with CD4+ T-cell counts

Background To investigate the factors associated with the diagnostic performance of interferon-gamma release assay (IGRA) on HIV infected patients with active tuberculosis (TB). Methods We retrospectively collected and analyzed the data of HIV infected patients with active tuberculosis hospitalized in Xixi Hospital of Hangzhou and Ruian people’s hospital of Wenzhou from January 1, 2016 to September 1, 2019. TB-IGRA was performed on all patients. For evaluating the diagnostic performance of TB-IGRA, all patients were divided into TB-IGRA positive group and TB-IGRA negative group. Results Among 184 patients, 133 patients were TB-IGRA positive and 51 patients were TB-IGRA negative. Performed by logistic regression analysis, we found that CD4+ T cell counts were an independent risk factor for false negative of TB-IGRA (OR=1.006, 95%CI 1.003-1.010, P<0.001). Additionally, the false negative rates of TB-IGRA were 68.75%, 27.77%, 20.58% and 14.63%, respectively, in the four groups whose CD4+ T cell counts were <20/μL (group 1, n=32), 20-50/μL (group 2, n=36), 51-100/μL (group 3, n=34) and >100/μL (group 4, n=82). The group 1 had the highest false negative rate, compared with other groups (P<0.001). However, there was no significant difference of the false negative rate between group 2 and 3 (P=0.483), group 3 and 4 (P=0.623). Conclusions The low level of CD4+ T cell counts could increase the false negative rate of TB-IGRA in HIV infected patients with active tuberculosis. And TB-IGRA may have unreliable diagnostic performance on HIV patients with active tuberculosis, especially when CD4+ T cell counts were <20/μL.