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Tuberculosis (TB) is one of the major causes of death worldwide with an estimated 10 million cases and 1.2 million deaths in 2018. About a quarter of the world’s population has been infected with M. tuberculosis. TB was the leading cause of death from a single infectious agent, ranking above HIV/AIDS up until the coronavirus (COVID-19) pandemic. TB affects people from the entire world, but over 95% of cases and deaths are from developing countries like Bangladesh which ranked seventh in overall highest incidence. The estimated incidence of TB in Bangladesh per 100,000 is 221 in, with a mortality rate of 24 per 100,000 population. Patients with chronic kidney disease (CKD) are at high risk for development or reactivation of tuberculosis (TB). TST is widely used in Bangladesh because of its low cost. However, in CKD patients, the sensitivity of this test is uncertain. A study performed in Kidney Foundation, Bangladesh showed low reactivity and high anergy in CKD patients. It is found that TST reliability is significantly low when compared with IGRA in CKD patients.
This is an observational study over a period of 6 years (2017-2023) . Around 99% of the patients presenting at Kidney Foundation Hospital are related to kidney disease including Chronic Kidney Disease, Haemodialysis, Peritoneal Dialysis, Transplant and Urological disorders etc. We observed the IGRA positivity in these patients over the last six years. The IGRA test is called QuantiFERON TB Gold Plus. The test contains four tubes, two with antigen tubes, TB1 and TB2: the TB1 tube contains ESAT-6- and CFP-10-derived peptides and is designed to induce CD4+ T cells response; the TB2 contains both the same long peptides of TB1 and newly designed peptides that stimulate IFN-γ production thereby acting as a positive control. The ESAT-6 and CFP-10 peptides are absent from all BCG strains and from most non-tuberculosis mycobacteria with the exception of M. kansasii, M. szulgai and M. marinum. There are negative and positive control tubes as well. The detection and subsequent quantification of IFN-γ forms the basis of this test.
IGRA was performed in 1811(SD181) patients between 2017 to 2023. About 364(18%)patients were positive and 1447(72%) patients were negative over 6 years. The average number of IGRA test done per year was 259 and on average 52(18%) were positive and 206(82%) were negative per year. In 2023 there were 198(26%) patients were IGRA positive and 562(73%)patients were IGRA negative. Among 198 patients 170(85.85%) CKD, 12(6%)ESRD, 5(2.5%) Transplant, 2(1%) Donor ,3(1.5%) Renal stones and 6(3%) unknown.
Kidney disease patients are at high risk for development of reactivation of tuberculosis. Monitoring and screening for LTBI is important. IGRA seems to have more sensitivity that the TST test in CKD patients but its cost makes it difficult to use it as a screening test in lower and lower middle income countries like Bangladesh who has a high incidence of Tuberculosis. IGRA can be used as a screening tool for Tuberculosis in CKD patients who has an anergy to TST test. Global overview 2020 WHO estimates that 23% of the world’s population (1.7 billion people) have LTBI, and 5–10% are expected to progress to develop TB disease during their lifetimes. Therefore, preventing active TB disease by screen and treat LTBI where appropriate is a critical part of the WHO End TB Strategy.