Anemia as a risk factor for tuberculosis: a systematic review and meta-analysis

Abstract

Background Tuberculosis is a major public health problem caused by Mycobacterium tuberculosis, occurring predominantly in population with low socioeconomic status. It is the second most common cause of death from infectious diseases. Tuberculosis becomes a double burden among anemic patients. Anemia increases an individual’s susceptibility to infectious diseases including tuberculosis by reducing the immunity level. Therefore, the purpose of this study was to determine whether anemia is a risk factor for tuberculosis. Method Relevant published articles were searched in electronic databases like PubMed, Google Scholar, EMBASE, and Cochrane Library using the following MeSH terms: risk factor, predictors, tuberculosis, TB, Anaemia, Anemia, hemoglobin, Hgb, and Hb. Articles written in the English, observational studies conducted on the incidence/prevalence of tuberculosis among anemic patients, or papers examined anemia as risk factors for tuberculosis were included. From those studies meeting eligibility criteria, the first author’s name, publication year, study area, sample size and age of participants, study design, and effect measure of anemia for tuberculosis were extracted. The data were entered using Microsoft Excel and exported to Stata version 11 for analysis. The random-effects model was applied to estimate the pooled OR and HR, and 95% CI. The sources of heterogeneity were tested by Cochrane I-squared statistics. The publication bias was assessed using Egger’s test statistics. Results A total of 17 articles with a 215,294 study participants were included in the analysis. The odd of tuberculosis among anemic patients was 3.56 (95% CI 2.53–5.01) times higher than non-anemic patients. The cohort studies showed that the HR of tuberculosis was 2.01 (95% CI 1.70–2.37) times higher among anemic patients than non-anemic patients. The hazard of tuberculosis also increased with anemia severity (HR 1.37 (95% CI 0.92–2.05), 2.08 (95% CI 1.14–3.79), and 2.66 (95% CI 1.71–4.13) for mild, moderate, and severe anemia, respectively). Conclusion According to the current systematic review and meta-analysis, we can conclude that anemia was a risk factor for tuberculosis. Therefore, anemia screening, early diagnose, and treatment should be provoked in the community to reduce the burden of tuberculosis.

Undernutrition and Treatment Success in Drug-Resistant Tuberculosis in Uganda

“…Interestingly, all these are known risk factors for active tuberculosis alongside undernutrition. 41 , 42 Nicotine in tobacco affects innate immune responses against TB by attenuating the expression of toll-like receptors and production of cytokines (IL – 6 and 8 and TNFα) and chemokines by lung epithelial cells, macrophages and type 2 pneumocytes. 43 , 44 Anaemia is associated with low CD4+ T-lymphocyte counts, delayed sputum culture conversion, and severe forms of TB.…”

Common and Rare Hematological Manifestations and Adverse Drug Events during Treatment of Active TB: A State of Art

“…Anemia has been considered a risk factor for the onset of infectious diseases and especially TB [ 6 ], as it increases individual susceptibility to such onset by reducing the immune response. Anemia is generally present at the time of diagnosis of TB.…”

“…Another factor to be considered is that anemia can also occur in the early phase of the treatment of TB after normal hematopoiesis reestablishment. As inflammation decreases during treatment, iron therefore becomes available for hematopoiesis, causing an increase in reticulocytes [ 5 , 6 , 7 ].…”

“…Hematological abnormalities involving the white blood cells can be associated with TB and include leukopenia, neutropenia, lymphocytopenia, monocytopenia, leukocytosis, neutrophilia, lymphocytosis and monocytosis, and pancytopenia (mainly in miliary TB) [ 3 ]. In a Chinese cross-sectional and follow-up study considering leukopenia in patients with TB, female gender, older age, duration of previous anti-TB treatment for more than 6 months [ 6 ] and use of antibiotics were risk factors for leukopenia. The prevalence of leukopenia in TB patients newly treated was 10.4%, while that of the previously treated TB patients was 9.1% [ 10 ].…”

Tuberculosis and anemia—cause or effect?

“…We read with interest the systematic review by Gelaw et al [ 1 ] from which the authors conclude that anemia is a risk factor for tuberculosis (TB), i.e., anemia precedes the development of TB disease. They explain this finding by immunosuppressive effects of anemia, either directly in the context of iron deficiency or indirectly through association with known risk factors for TB such as malnutrition, and recommend early diagnosis and treatment of anemia to help reduce the burden of TB.…”