Usefulness of a preoperative inflammatory marker as a predictor of asymptomatic acute rejection after lung transplantation: a Japanese single-institution study

BACKGROUND: Surveillance bronchoscopy (SB) is performed as routine follow-up after lung transplantation (LTx), primarily for the early detection of clinically asymptomatic acute rejection (AR). To identify appropriate candidates for SB over a long period, we explored risk factors of asymptomatic AR after LTx. METHOD: This study is a single-center and retrospective cohort study. Forty-five patients underwent cadaveric LTx between 2000 and 2016 in our institution. All enrolled patients had at least three months of follow-up. SB is scheduled at 1, 2, 3, 6, and 12 months after LTx routinely and annually thereafter until 5 years after LTx. A histological assessment for AR was performed according to the International Society for Heart and Lung Transplantation (ISHLT) criteria. The analysis of potential risk factors for AR was performed using a chi-square test and logistic regression analysis. RESULTS: The median period of follow-up after LTx for the entire cohort was 64 months. Asymptomatic AR (grade A1-A3) was detected in 22 patients, 14 of whom showed severe AR (worse than grade A2). The percentage of patients with AR was 5–24% at each time point, and 15% of patients still showed severe AR (A2 and A3) at 24 months after LTx. Potential risk factors included recipient factors (diagnosis, age, gender, BMI), donor factors (age, gender, smoking history, cause of brain death), HLA mismatch, operation-related factors, neutrophil-to-leucocyte ratio (NLR), platelet-to-leucocyte ratio (PLR), and other scores. Patients with a higher NLR showed a higher incidence of AR after LTx than others during follow-up (P=0.01). CONCLUSIONS: An increased perioperative NLR was significantly associated with a higher odds ratio of AR during follow-up. Patients with a high NLR seem to be good candidates for long-term SB.