Introduction Accurate pre-lung transplant biomarkers of post-lung transplant survival are lacking in Idiopathic Pulmonary Fibrosis (IPF).

Methods This was a retrospective, observational study including consecutive patients diagnosed with IPF at the University of South Florida/ Tampa General Hospital. First, we compared survival differences in patients with IPF that received lung transplant versus non- recipients, then we investigated whether pre-transplant monocyte counts could predict post- lung transplant survival, Primary Graft Dysfunction (PGD), Acute Cellular Rejection (ACR), Antibody-Mediated Rejection (AMR) and Chronic Lung Allograft Dysfunction (CLAD) using Cox Proportional Hazards (CoxPH) models adjusted to Gender, Age and Physiology index (GAP).

Results A total of 201 patients with IPF were included in the analysis [lung transplant recipients: n=103, non-recipients of lung transplant: n=98]. Patients with IPF that did not undergo lung transplantation had significantly worse survival compared to patients with IPF that underwent lung transplantation [3.13 years (95% CI: 2.30 to 3.72) vs 7.05 years (95% CI: 5.41 to 8.48), HR: 2.95 (95% CI: 2.18 to 4.00), p<0.0001]. Patients with IPF and pre-lung transplant monocyte counts>700 K/μL had increased risk of post-lung transplant mortality [HR: 1.71 (95%CI: 1.10 to 2.65), p=0.016] or adverse outcomes defined as either PGD, ACR, AMR or CLAD, [HR: 2.05 (95% CI: 1.11 to 3.78), p=0.02] compared to patients with monocyte counts≤700 K/μL.

Conclusion Lung transplantation substantially prolongs survival of patients with IPF. Incorporation of pre-lung transplant monocyte counts in the pre-transplant evaluation of patients with IPF could optimize the selection of ideal lung transplant candidates with increased probability of survival.

The authors have declared no competing interest.

This study was funded by the Ubben Family Fund (JHM).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethical approval for this study was given by the Institutional Review Boards / Research Integrity & Compliance of University of South Florida (STUDY: 008038).

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Data are available upon request to the corresponding author.