The usefulness of quantitative interferon-gamma releasing assay response for predicting active tuberculosis in kidney transplant recipients: A quasi-experimental study.

OBJECTIVES: We evaluated the effectiveness of IGRA-based isoniazid (INH) treatment with the diagnostic value of quantitative IGRA titer for post-transplant tuberculosis (TB) in kidney transplant (KT) recipients. METHODS: All adult KT recipients were enrolled from January 2014 to December 2017. The development of TB after KT was observed, stratified by quantitative IGRA results as well as by IGRA results with/without INH treatment. RESULTS: Of 1150 KT recipients, 322 (28%) revealed positive IGRA results (≥0.35 IU/mL) and 12 (1.0%) developed TB. Seven (3.2%) of 217 patients with positive IGRA without INH developed TB, whereas none of 105 patients with positive IGRA with INH developed TB (rate difference -1616 per 100,000 person-years, P = 0.016) and 5 (0.6%) of 828 patients with negative or indeterminate IGRA developed TB (rate difference -1388 per 100,000 person-years, P<0.001). Among the 217 positive IGRA patients without INH, 6 (6.4%) of 94 patients who had positive IGRA titer>2.96 IU/mL developed TB, whereas one (0.8%) of 123 patients who had positive IGRA titer≤2.96 IU/mL developed TB (rate difference 2964 per 100,000 person-years, P = 0.017). CONCLUSIONS: IGRA-based INH treatment with risk stratification by quantitative IGRA results appears to be effective to prevent the development of TB in KT recipients.