P57 peripheral blood monocyte count as a prognostic marker in fibrotic interstitial lung disease (fILD): analysis from a single UK specialist centre

Wallis, T.J.M., Pontoppidan, K., Brereton, C.J., Welham, B., Jones, M.G. and Fletcher, S.V. (2019) P57 peripheral blood monocyte count as a prognostic marker in fibrotic interstitial lung disease (fILD): analysis from a single UK specialist centre. Thorax, 74 (Suppl 2), A120-A121. (doi:10.1136/thorax-2019-BTSabstracts2019.200).

Abstract

Background: predicting individual patient course and prognosis in fILD is challenging and there are no established prognostic biomarkers to aid clinical judgement. An association between peripheral blood monocyte (PBM) count and survival was recently proposed in patients with Idiopathic Pulmonary Fibrosis (IPF) (Scott et al. Lancet Respir Med 2019–7:497– 508). We investigated in a single UK centre whether monocyte count was an independent predictor of survival in cohorts of patients with an MDT diagnosis of IPF, chronic hypersensitivity pneumonitis (cHP) and unclassified ILD (uILD).

Methods: single centre study of consecutive patients with an MDT diagnosis of IPF, cHP or uILD. Electronic records and blood results were reviewed. The PBM count nearest to the MDT diagnosis was imputed. Time to death/transplant was calculated by Kaplan-Meier analysis and cumulative risk of death/transplant quantified by multivariate Cox-regression analysis (IBM-SPSS®v25).

Results: 385 patients (IPF n= 199, cHP n= 101, uILD n=85) were included. Baseline demographics, IPF-cHP-uILD respectively - mean (SD). Age (years): 72.7 (7.8), 66.6 (12.3), 71.7 (8.4). FVC% predicted (FVC%pred): 73.8% (19.8), 77.0% (20.0), 83.5% (20.8). DLCO%pred: 46.5% (15.1), 53.8% (15.3), 57.1% (18.1). Gender: (Males%): 76.1%, 36.0%, 61.7%.

The IPF cohort had significantly higher absolute PBMs compared to cHP but not uILD (0.77x109/L vs 0.65x109/L vs. 0.74x109/L respectively IPFvs.HP p0.94x109/L (Mono>0.94) or Low≤0.94x109/L (Mono≤0.94) as Scott et al. 2019; in the IPF cohort Mono>0.94 was associated with significantly reduced time to death/transplant compared to Mono≤0.94 (171.7weeks (95%CI 132.6–210.8weeks) vs. 262.2weeks (95%CI 211.7–312.7weeks) p=0.035). Multivariate Cox-regression analysis (age, sex, FVC%pred and DLCO%pred) identified Mono>0.94 as an independent predictor of death/transplant in IPF; Hazard-Ratio 1.576 (95%CI 1.023–2.300) p=0.031. There was no association between absolute or stratified monocyte count and survival in the cHP or uILD cohorts.

Conclusions: in this UK single-centre study a stratified PBM of >0.94x10*9/L was an independent risk factor for death/transplant in IPF but not in patients cHP or uILD. Prospective studies are required to confirm this observation.

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