Risk of tuberculosis after lung transplantation: the value of pretransplant chest computed tomography and the impact of mTOR inhibitors and azathioprine use

Background. It is necessary to determine the incidence and risk factors for tuberculosis (TB), as well as strategies to assess and treat latent tuberculosis infection (LTBI) in lung transplant recipients. Methods. A retrospective cohort study of 398 lung transplant recipients was performed. Episodes of TB were studied and the incidence rate was calculated. Logistic regression analysis was used to analyze specific variables as potential risk factors for TB. Results. Median follow-up was 558 days (range 1-6636). Six cases (1.5%) of TB were documented in 398 transplant patients. The incidence density of TB was 406.3 cases/10(5) patient-years (95% confidence interval [CI] 164.7-845), which is higher than in the general population (13.10 cases/10(5) person-years). All cases occurred in the period 1993-2006, when the tuberculin skin test (TST) and treatment of LTBI in positive TST patients were not part of the protocol. Pretransplant computed tomography (CT) showed residual lesions in 50% of patients who developed TB, although the TST was negative and the chest radiograph was inconclusive. Multivariate analysis identified the presence of residual lesions in the pretransplant chest CT (odds ratio [OR] 11.5, 95% CI 1.9-69.1, P = 0.008), use of azathioprine (OR 10.6, 95% CI 1.1-99.1, P = 0.038), and use of everolimus (OR 6.7, 95% CI 1.1-39.8, P = 0.036) as independent risk factors for TB. Conclusions. Residual lesions in the pretransplant chest CTs and the use of azathioprine and mTOR inhibitors are associated with the risk of TB.