A multi-centric study to underscore the prevalence of latent TB infection and Active tuberculosis in patients of chronic kidney disease: Intervention in high TB burden Country

Background Chronic kidney disease (CKD) increases the risk of active tuberculosis (TB) and tuberculosis infection (TBI). This systematic screening estimated prevalence of both, along with concordance of Cy-TB and Interferon gamma release assay (IGRA) in these patients. Methods A multi-center prospective study was conducted across two nephrology OPDs in high-burden tertiary care centers from February 2024 to April 2025. All consenting patients with chronic kidney disease (CKD) were systematically screened for pulmonary TB and TBI using the ‘4S symptom screen’, Chest X-ray, Cy-TB, IGRA, cartridge-based nucleic acid amplification test (CBNAAT), and sputum for acid-fast bacilli (AFB). Positive CBNAAT, culture or histopathology was considered as active TB disease, and positive IGRA and/or Cy-Tb in the absence of clinical, radiological, or microbiological evidence of active TB was considered TBI. The diagnostic utility of Cy-TB and IGRA was estimated. Results Of 13,342 screened patients, 632 completed full diagnostic cascade. Abnormal X-ray, positive Cy-TB alone, positive IGRA alone, both Cy-TB/IGRA positive and CBNAAT were positive in 36.39%, 34.6%, 42.9%, 10.75% and 6.32% respectively. Accordingly, TB disease and TBI were assessed in 6.3% and 25% of patients, respectively. Cy-TB and IGRA demonstrated sensitivities of 36.4% and 27.6%, respectively. The concordance between Cy-Tb and IGRA was 54.48% in the screened population and 59.13% in the study cohort, with corresponding discordance rates of 45.14% and 40.87%, respectively, highlighting significant variability between the two assays in this population. However, the negative predictive value was 96.37% for Cy-TB and 92.13% for IGRA for active TB. Low body mass index (BMI), unemployment, and hypertension were significantly associated with the infection status. Conclusion Patients with chronic kidney disease had a markedly higher prevalence of active tuberculosis than the general population, whereas tuberculosis infection was less frequent than national estimates. Moderate agreement of concordance between IGRA and Cy-Tb necessitates a prospective study incorporating clinical and bacteriological investigation for its confirmation.