Effect of aerosolized antipseudomonals on Pseudomonas positivity and bronchiolitis obliterans syndrome after lung transplantation

Purpose: To describe the effects of aerosolized antipseudomonals (AAPs) on Pseudomonas (PS) culture positivity, bronchiolitis obliterans syndrome (BOS), and acute cellular rejection (ACR) in lung transplant recipients (LTRs).

Methods: Single-center, retrospective cohort study was performed of adult LTRs treated with either AAP for ≥28 days vs no AAP therapy or AAP therapy <28 days, indexed to a matched median date post lung transplantation (LT). Primary outcome was freedom from PS positivity by positive bronchoalveolar lavage or bronchial wash at 1 year. Secondary outcomes were freedom from BOS or BOS progression and ACR burden (defined by the novel composite rejection standardized score. Normality was assessed, and univariate and multivariate parametric and non-parametric statistical tests were used to assess baseline characteristics and outcomes, where appropriate. Freedom from events was compared using the Kaplan-Meier method with log-rank conversion and risk was assigned using multivariable Cox proportional hazards (PH) modeling.

Results: In total, 293 LTRs (105 with AAP, 188 with no AAP) were included. Median ages in AAP and control cohorts were 51 (30-63) and 62 (54-67) years (P<.01). Median AAP duration was 198 (interquartile range 94-395) days. Time to median positive PS culture was similar between AAP (median 1.02 [95% confidence interval {CI} 0.74-1.22] years) and control (median 0.96 [95% CI 0.72-1.21] years). Log-rank test for time-to-PS positivity was similar for both groups (log-rank P=.26). Incidence of PS culture positivity at 1 year was similar in APP vs controls (59.0% vs 54.8%, P=.48). In the non-cystic fibrosis (CF) subgroup, AAP use was protective against PS recurrence on univariate Cox PH model (hazard ratio [HR] 0.55, 95% CI 0.38-0.83) and on multivariate Cox PH adjusting for age and induction (HR 0.56, 95% CI 0.38-0.83). Incidence of new-onset BOS or BOS progression in APP vs control at 1 (17.1% vs 14.9%, P=.61) and 3 (38.1% vs 37.8%, P=.96) years was similar. CRSS was similar in APP vs control group at 1 year (0.42 vs 0.33, P=.41).

Conclusion: AAP use was not associated with less PS positivity, BOS, or ACR in all LTRs. In the non-CF subgroup analysis, treatment with AAPS was associated with protection against recurrent PS. Limitations include retrospective design, heterogeneous AAP therapy among LTRs, and potential convenience sampling of LTRs receiving AAPs for >28 days at our center. Larger assessments and better controlled analyses are required to further define efficacy of AAPs after LT.