Impact of anemia on prognosis in tuberculosis patients

BACKGROUND: Anemia 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. METHODS: In 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. RESULTS: Compared 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. CONCLUSIONS: Anemia is a risk factor for lung injury in TB patients. Inflammatory factors and inflammatory cells are increased during treatment in A-TB patients.