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Anemia in tuberculosis cases: A biomarker of severity?

ABSTRACT:

Introduction

Anemia is a common condition at tuberculosis diagnosis, and there is evidence that its prevalence is higher in patients with tuberculosis than in those infected with Mycobacterium tuberculosis and healthy controls. Information about anemia during tuberculosis diagnosis is still scarce in the Brazilian population. The aim of this study was to describe the prevalence of anemia in patients with tuberculosis cared for at a referral center and its association with clinical forms of tuberculosis and other characteristics of these patients.

Materials and methods

This was a retrospective cross-sectional study of tuberculosis patients diagnosed from January 2015 to December 2018 at the Clinical Research Laboratory on Mycobacteria (LAPCLIN-TB) of Evandro Chagas National Institute of Infectious Diseases (INI)/Oswaldo Cruz Foundation (Fiocruz). A database of an ongoing cohort study underway at this service since 2000 provided the baseline information on tuberculosis cases extracted from a visit template. Exploratory and logistic regression analyses were performed to verify associations between anemia and demographic characteristics, socioeconomic status, clinical conditions, and laboratory results.

Results

Of the 328 cases reviewed, 70 were excluded, with258 retained. The prevalence of anemia was 61.2% (27.5% mild, 27.5% moderate and 6.2% severe). Among patients with anemia, 60.8% had normochromic normocytic anemia, and 27.8% showed hypochromic microcytic anemia. In logistic regression analysis, anemia was associated with a history of weight loss >10%, hospitalizations, coinfection with HIV, increased platelet count and microcytosis. Anemia was more frequent in the most severe clinical forms, such as meningeal and disseminated tuberculosis.

Conclusions

Anemia was highly prevalent in tuberculosis patients at diagnosis, predominantly as normochromic normocytic anemia and in mild and moderate forms. It was associated with baseline characteristics and conditions indicative of severe disease, suggesting that anemia could be a biomarker of tuberculosis severity.

SUBMITTER: de Mendonca EB

PROVIDER: S-EPMC7853529 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundAnemia is one of the risk factors for tuberculosis (TB), and more than 90% of TB patients suffer from anemia. The majority tuberculosis patients who had poor prognosis experienced anemia during the course of treatment. The objective of our study is to analyse the influences of anemia on the prognosis of tuberculosis patients in terms of pulmonary M. tuberculosis loads, lung pathology, and clinical factors.MethodsIn this retrospective cohort study, 155 TB patients in Shanghai were divided into the anemia-tuberculosis (A-TB) group and non-anemia-tuberculosis (NA-TB) group. We analysed bacteria counts in sputum smear and sputum smear conversion time between two groups. We evaluated the pulmonary pathology of cavity and effusion in A-TB patients. Logistic regression analysis was performed to explore the potential correlations of anemia with sputum bacterial load and pulmonary pathology. We compared clinical factors including the immune factors and inflammatory cells.ResultsCompared with the NA-TB (n=89) group, the A-TB group (n=66) had poorer improvement of lung injury in terms of cavity closure (4.7±3.59 vs. 10.56±7.42; P=0.036) and fluid improvement [4 (30.77%) vs. 12 (92.31%); P=0.001] during conventional treatment. At the start of treatment, the immune factors complement 4 (C4) [0.25 (0.19, 0.295) vs. 0.3086±0.076; P=0.006] and C-reactive protein (CRP) [3.2 (3.2, 21.5) vs. 19.5 (6.25, 78.35); P=0.016] were significantly higher in A-TB with NA-TB. During the course of treatment, the gradual decrease in the absolute number of lymphocytes (LYM#) (P=0.0012, r=-0.3400) and the gradual increase in the absolute number of monocytes (MONO#) (P=0.0050, r=0.2968), the absolute number of basophils (BASO#) (P=0.0213, r=0.2451), the red blood cell distribution width-coefficient (RDW-CV) (P=0.0136, r=0.2651), suggesting poor prognosis in anemic TB patients.ConclusionsAnemia is a risk factor for lung injury in TB patients. Inflammatory factors and inflammatory cells are increased during treatment in A-TB patients.