790. The Efficacy of the Interferon-γ Releasing Assay-Based Isoniazid Treatment for Preventing Active Tuberculosis in Kidney Transplant Recipients: A Quasi-experimental Study

BACKGROUND: Interferon-γ releasing assays (IGRAs) are useful for diagnosing LTBI. However, there are limited data on the efficacy of IGRA-based isoniazid (INH) treatment with/without back-up tuberculin skin test (TST) to prevent the development of TB in solid-organ transplant recipients. METHODS: All adults patients admitted to a KT unit from January 2014 to December 2016 were retrospectively reviewed in a 2,700-bed, tertiary-care hospital in Seoul, South Korea. The IGRA (i.e., QuantiFERON-In-Tube) with/without TST was performed on all recipients before KT, and 9-month INH treatment was given to patients with clinical risk factors for LTBI regardless of IGRA results. Our hospital policy on LTBI diagnosis and treatment was changed as follows. Period 1 (January 2014–September 2015) adopted IGRA-based INH treatment. We administered INH treatment to all patients with positive IGRA results. Period 2 and period 3 adopted IGRA-based followed by back-up TST-based INH treatment. Period 2 (October 2015–December 2015) included the temporary shortage of Mantoux test, so INH treatment was not given to the patients with positive IGRA since back-up TST was not performed. In Period 3 (January 2016–December 2016), we administered INH treatment to the patients with positive IGRA results followed by back-up TST¡Ã10 mm. The development of TB after KT as the primary endpoint was observed from January 2014 to April 2018. RESULTS: The study flow is shown in Figure 1. Of the 1,150 KT recipients, 14 (1.2%) developed TB (incidence rate 0.63 per 100 person-years, 95% CI 0.35–1.06). The median time for TB development was 9.4 months (IQR 4.7–14.5). Seven (3.2%) of 216 patients with positive IGRA without INH treatment developed TB, whereas none of 106 patients with positive IGRA with INH treatment developed TB (rate difference 2.43 per 100 person-years, P = 0.008) and 7 (0.8%) of 828 patients with negative or indeterminate IGRA results developed TB (rate difference 2.0 per 100 person-years, P < 0.001). The number needed to treat (NNT) for IGRA-based INH treatment was 31 (95% CI 18–114). CONCLUSION: IGRA-based INH treatment is effective to prevent the development of TB in KT recipients without clinical risk factors for LTBI with reasonable NNT. [Image: see text] DISCLOSURES: All authors: No reported disclosures.