Relevance between the risk of developing Tuberculosis and Immunity performance among HIV positive patients

Abstract

Background: According to the World Health Organization (WHO) report, Mongolia has a low prevalence of Human Immunodeficiency virus (HIV) in general population (<0.1%) and concentrated prevalence among key population (>5%). However, the prevalence of Tuberculosis (TB) is high among general population, ranking it at the 4th place among 37 countries of Western Pacific Region due to prevalence and incidence of TB. This indicates the high risk of HIV/TB coinfection even though the number of people living with HIV is few in our country. Thus, the study was conducted aiming to identify the HIV/TB coinfection situation, and the relationship of risk for TB disease and immunity performance among people living with HIV (PLHIV). Method: We conducted the study with retrospective cohort design, using the outpatient card and medical chart of 281 patients, out of 286 PLHIV who were diagnosed between 1997-2019 at the AIDS/STI Surveillance and Research Department of National Center for Communicable Diseases. Results: Among 281 patients, 54 patients (19.2%) were diagnosed with HIV/TB coinfection and 18 patients (6.4%) were diagnosed with coinfection at the time of HIV diagnosis while 36 patients (19.2%) were diagnosed during the follow-up period. The CD4+ cell count and CD4/CD8 ratio of the HIV patient were 362.8±205.4 cell/ml and 0.35±0.23 respectively at the time of HIV diagnosis while they were lower in HIV patients with TB with 274.3±186.9 cell/ml, 0.28±0.22. When we compared those diagnosed with TB at the same time of HIV diagnosis and HIV patients who diagnosed with TB at the late stage or follow-up period, the CD4+ cell count was 176.1±197.4 cell/ml and 323.4±162.9; and CD4/CD8 ratio was 0.20±0.25 бa 0.32±0.20 respectively. The CD4+ cell count was 262.9±190.0 cell/ml among those had pulmonary TB while it was 299.1±183.3 cell/ml among with extrapulmonary TB. The pre-indication of risk of developing HIV/TB coinfection among PLHIV was related to the cell immunity suppression including fewer CD4+ cell and reduction of CD4/CD8 ratio. Being HIV positive and aged above 32 years increased the risk of TB diseases at the HIV diagnosis by 4.4 times and the sensitivity of HIV/TB coinfection could be up to 83.3% among HIV patients who are above 32 years old. Also, being above 32 years old increased the odds of TB diseases by 2.3 times. Conclusion: The risk of developing TB diseases was associated with cell immunity suppression defined by reduction of CD4+ cell count and CD4/CD8 ratio. The older age increased the risk of TB diagnosis at the same time of HIV diagnosis and pulmonary TB while being diagnosed at the AIDS stage increases the risk of coinfection of TB, particularly the risk for the occurrence of TB diseases at the time of HIV/AIDS diagnosis.