AVALIAÇÃO DE ESTRATÉGIAS DE RASTREAMENTO PARA DIAGNÓSTICO DE INFECÇÃO LATENTE POR MYCOBACTERIUM TUBERCULOSIS EM PESSOAS VIVENDO COM HIV/AIDS

Abstract

Tuberculosis (TB) is one of the main causes of death in people living with HIV/Aids (PLHA) and the treatment of latent infection by Mycobacterium tuberculosis (LTBI) is one of the pillars of TB control. We evaluated two different strategies for screening for LTBI in PLHA treated at an infectious disease referral center in Campo Grande, MS. Study participants were PLHA aged 18 years or older. Cases with active TB, previous LTBI treatment, tuberculin skin test (TST) performed less than 6 months ago, unavailability to return for TST reading and unavailability or impossibility of collecting blood to perform the interferon gamma release assay (IGRA) were excluded. IGRA with QuantiFERON® TB Gold Plus (QFT-Plus), TST and posteroanterior and lateral chest radiography were performed. Cases of LTBI were those with positive IGRA or positive TST (test in parallel) and ruled out active TB in the medical evaluation. A total of 296 participants were included, with a median age of 44 (IQR1 =33.3; IQR3= 54) years, with a predominance of men (60.8%), non-white (67.2%). They had a median CD4+ count of 556 (IQR1 =395; IQR3= 774.5) cells/mm³ and 88.2% had an undetectable viral load. The prevalence of LTBI was 15.9% (95% CI: 11.9% – 20.6%) TT positivity was 7.4% (95% CI: 4.7%-11.0%) and QFT-Plus was 12.8% (95% CI 9.3%-17.3%). The prevalence of LTBI was higher in those with a CD4+ count equal to or greater than 350 cells/mm3 than among those with a CD4+ count of less than 350 cells/mm3 (6.8% vs 18.1%; p=0.033). While TT positivity was more frequent in those with a CD4+ count equal to or greater than 350 cells/mm3 (p=0.010), this was not observed with the QFT-Plus (p=0.116). Thirty-four (11.5%) patients showed disagreement between the results of the IGRA and TST tests. The kappa coefficient of the tests revealed only a reasonable agreement (k=0.374, CI 95% 0.177 – 0.572; p=0.001). We did not observe associations between clinical and epidemiological variables and the occurrence of discordant tests. The IGRA identified more cases of LTBI when compared to the TST, however 9 of the 48 patients could only be diagnosed with LTBI by the TST. In conclusion, the use of the two tests, QFT-Plus and TT in parallel, in PLHA was able to detect more cases of LTBI than the TT alone and the results point to the superiority of QFT-Plus among those with CD4+.