Household contact as a key risk factor for latent tuberculosis infection among patients with diffuse large B-cell lymphoma

Introduction: Patients with diffuse large B-cell lymphoma (DLBCL) have an increased risk of reactivating latent tuberculosis infection (LTBI) into active tuberculosis (TB) during chemotherapy or hematopoietic stem cell transplantation. However, extensive testing for LTBI among all patients is not practical, especially in regions with limited health resources. Objective: This study aimed to identify risk factors associated with an increased risk of LTBI among patients with newly diagnosed DLBCL and to determine the prevalence of LTBI in these patients. Materials and Methods: A retrospective cohort study of patients with newly diagnosed DLBCL was conducted at Ching Rai Prachanukroh Hospital from September 2020 to June 2023. All patients were screened for LTBI using interferon-release assays (IGRAs), either the QuantiFERON-TB Gold In-Tube (QFT) or T-SPOT.TB (T-SPOT) tests, after DLBCL diagnosis and before the start of treatment. Data were collected from medical records. Generalized linear models were used to estimate the adjusted risk ratio (RR) and 95% confidence interval (CI) for LTBI risk factors. Results: A total of 127 patients with newly diagnosed DLBCL were enrolled, with a mean age of 59.17 years. Among them, 17 patients had IGRAs-proven LTBI, resulting in an prvalence of 13.39%. The results showed that household contact with TB significantly increased the risk of LTBI (adjusted RR: 3.24, 95% CI: 1.51-6.14). Conclusion: Patients with newly diagnosed DLBCL patients who had household contact with TB had a significantly higher risk of LTBI. These findings highlight the importance of targeted LTBI screening among patients with newly diagnosed DLBCL, particularly those with household contact with TB.