Interplay between systemic inflammation, anemia, and mycobacterial dissemination and its impact on mortality in TB-associated HIV: a prospective cohort study

Abstract

Introduction: Anemia frequently affects people living with HIV (PLHIV). Nevertheless, the impact of anemia on treatment outcomes of patients with HIV-associated tuberculosis (TB) and the underlying molecular profiles are not fully characterized. The aim of this study was to investigate the interplay between anemia, the systemic inflammatory profile, dissemination of TB and death in HIV-TB patients in an ad hoc analysis of results from a prospective cohort study.

Methods: 496 hospitalized PLHIV ≥18 years old, with CD4 count <350 cells/μL and high clinical suspicion of new TB infection were enrolled in Cape Town between 2014-2016. Patients were classified according to anemia severity in non-anemic, mild, moderate, or severe anemia. Clinical, microbiologic, and immunologic data were collected at baseline. Hierarchical cluster analysis, degree of inflammatory perturbation, survival curves and C-statistics analyses were performed.

Results: Through the analysis of several clinical and laboratory parameters, we observed that those with severe anemia exhibited greater systemic inflammation, characterized by high concentrations of IL-8, IL-1RA and IL-6. Furthermore, severe anemia was associated with a higher Mtb dissemination score and a higher risk of death, particularly within 7 days of admission. Most of the patients who died had severe anemia and had a more pronounced systemic inflammatory profile.

Discussion: Therefore, the results presented here reveal that severe anemia is associated with greater TB dissemination and increased risk of death in PLHIV. Early identification of such patients through measurement of Hb levels may drive closer monitoring to reduce mortality. Future investigations are warranted to test whether early interventions impact survival of this vulnerable population.

Keywords: HIV; anemia; mortality; systemic inflammation; tuberculosis.

Figure 1

Association of anemia severity with Mtb dissemination and death. (A) Distribution of dissemination score according to anemia severity. (B) Distribution of deaths and time to death according to anemia severity. Early deaths were defined as deaths occurring within 7 days of enrolment, and late deaths were all deaths that occurred after 7 days and within 12 weeks of enrolment. (C) Hb levels according to dissemination score. (D) Hb levels according to time of death. Groups were compared using the Mann–Whitney U test. The Cochran–Armitage test for trend was used to assess the tendency of increased levels or frequencies among groups. (E, F) ROC curve analysis was used to evaluate the accuracy of Hb values to discriminate high dissemination score (Mtb dissemination score 3) (E) and early death (F). Colored dots indicate the cut-off values of Hb extracted from the ROC curve analyses that resulted in the optimal ratio between sensitivity and specificity; these values are described in the indicated panels. Mild anemia was defined as Hb value >10 g/dL and <13 g/dL for men; and >10 and <12 g/dL for women, whereas moderate anemia was defined as Hb>8 g/dL and <=10 g/dL for both sexes. Severe anemia was defined as Hb<8g/dL for both sexes.

Figure 2

Association of anemia severity with inflammatory profile. (A) Left panel: A heatmap was designed to depict the overall pattern of inflammatory markers. A one-way hierarchical cluster analysis (Ward’s method) was performed. Dendrograms represent Euclidean distance. Right panel: Several analyses were performed to identify trends of increasing or decreasing of biomarker levels across anemia severity. Significant differences (p < 0.05) are highlighted in red-brown trend symbol when the trend is increasing and in yellow when the trend is decreasing. For those of no significance, there is a beige circle. (B) Scatter plots of the degree of inflammatory perturbation (DIP) value grouped according to anemia severity. Lines in the scatter plots represent median values and data were compared using the Mann–Whitney U test. The Cochran–Armitage test for trend was used to assess the tendency of increased levels or frequencies among groups. (C) We identified the Top 10 biomarker scores contributing to overall perturbation. The score was obtained using DIP approach. Mild anemia was defined as Hb value >10 g/dL and <13 g/dL for men; and >10 and <12 g/dL for women, whereas moderate anemia was defined as Hb>8 g/dL and <=10 g/dL for both sexes. Severe anemia was defined as Hb<8g/dL for both sexes.

Figure 3

Degree of Inflammatory Perturbation (DIP) according to dissemination score and death. (A) Scatter plots of the DIP value grouped according to dissemination score. Lines in the scatter plots represent median values and data were compared using the Mann–Whitney U test. (B) Scatter plots of the DIP value grouped according to death. Lines in the scatter plots represent median values and data were compared using the Mann–Whitney U test. (C, D) ROC curve analysis was used to evaluate the accuracy of DIP values to discriminate high dissemination score (Mtb dissemination score 3) (C) and early death (D). Colored dots indicate the cut-off values of DIP extracted from the ROC curve analyses that resulted in the optimal ratio between sensitivity and specificity; these values are described in the indicated panels.

Figure 4

A more pronounced inflammatory profile is associated with severe anemia and death. (A) Left panel: An unsupervised two-way hierarchical cluster (Ward’s method) was performed with all 496 participants. Data were log10 transformed and ranked and colored in a heatmap from values detected for each inflammatory biomarker. Dendrograms represent Euclidean distance. Three main clusters were defined. Right panel: A log10 fold change was performed comparing each cluster with reference cluster (C2, due to lowest frequency of dissemination and death). Significant differences (p < 0.05) are highlighted in blue bars. (B) For each cluster, shaded areas represent frequency of death (red), anemia severity grade (light blue to dark purple) and Mtb dissemination score (light green to dark green) and. Chi squared test was performed to each variable comparing clusters. (C) Survivor curves show the probability of survival over 12 weeks for each cluster. Mild anemia was defined as Hb value >10 g/dL and <13 g/dL for men; and >10 and <12 g/dL for women, whereas moderate anemia was defined as Hb>8 g/dL and <=10 g/dL for both sexes. Severe anemia was defined as Hb<8g/dL for both sexes.