title: The effect of incident tuberculosis on immunological response of HIV patients on highly active anti-retroviral therapy at the university of Gondar hospital, northwest Ethiopia: a retrospective follow-up study.
abstract: BACKGROUND
  Human immunodeficiency virus (HIV) infection is usually complicated by high rates of tuberculosis (TB) co-infection. Impaired immune response has been reported during HIV/TB co-infection and may have significant effect on anti-retroviral therapy (ART). TB/HIV co - infection is a major public health problem in Ethiopia. Therefore, the aim of the study was to assess the effect of TB incidence on immunological response of HIV patients during ART.
  
  
  METHODS
  A retrospective follow-up study was conducted among adult HIV patients who started ART at the University of Gondar Hospital. Changes in CD4+ T - lymphocyte count and incident TB episodes occurring during 42 months of follow up on ART were assessed. Life table was used to estimate the cumulative immunologic failure. Kaplan-Meier curve was used to compare survival curves between the different categories. Cox-proportional hazard model was employed to examine predictors of immunological failure.
  
  
  RESULTS
  Among 400 HIV patients, 89(22.2%) were found to have immunological failure with a rate of 8.5 per 100 person-years (PY) of follow-up. Incident TB developed in 26(6.5%) of patients, with an incidence rate of 2.2 cases per 100 PY. The immunological failure rate was high (20.1/100PY) at the first year of treatment. At multivariate analysis, Cox regression analysis showed that baseline CD4+ T - cell count <100 cells/mm3 (adjusted hazard ratio (AHR) 1.8; 95%CI: 1.10 - 2.92, p = 0.023) and being male sex (AHR 1.6; 95%CI: 1.01 - 2.68, p = 0.046) were found to be significant predictors of immunological failure. There was borderline significant association with incident TB (AHR 2.2; 95%CI: 0.94 - 5.09, p = 0.06). The risk of immunological failure was significantly higher (38.5%) among those with incident TB compared with TB - free (21.1%) (Log rank p = 0.036).
  
  
  CONCLUSIONS
  High incidence of immunological failure occurred within the first year of initiating ART. The proportions of patients with impaired immune restoration were higher among patients with incident TB. Lower baseline CD4+ T - cells count of <100 cells/mm3 and being male sex were significant predictors of immunological failure. The result highlighted the beneficial effects of earlier initiation of ART on CD4+ T - cell count recovery.
authors.affiliation: Department of Medical Microbiology, College of Medicine and Health Sciences, School of Biomedical and Laboratory Sciences, University of Gondar, Gondar, Ethiopia. abezew@gmail.com.
authors.forename: Abate
authors.initials: A
authors.lastname: Assefa
authors.forename: Baye
authors.initials: B
authors.lastname: Gelaw
authors.forename: Gebeyaw
authors.initials: G
authors.lastname: Getnet
authors.forename: Gashaw
authors.initials: G
authors.lastname: Yitayew
mesh_terms: D000293:Adolescent; D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D060085:Coinfection; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000150:complications / Q000188:drug therapy* / Q000382:microbiology; D006761:Hospitals; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D014376:Tuberculosis / Q000150:complications*; D055815:Young Adult