P28 Prognostic value of routine peripheral blood markers in fibrotic hypersensitivity pneumonitis. (11th November 2022) - Stock, CJW
Abstract : A proportion of patients with fibrotic hypersensitivity pneumonitis (fHP) follow a progressive disease course despite immunosuppressive treatment. We aimed to investigate the impact of routinely measured baseline blood biomarkers on mortality in fHP. Baseline demographics were recorded for consecutive patients with a diagnosis of fHP; discovery cohort (2010–2014) n=125, validation cohort (2015–2019) n=173. Patients were included if they had full blood count measurements performed within 3 months of first lung function test at our unit (baseline). Cox proportional hazards analyses were performed to test for associations with all-cause mortality. Step-wise backwards elimination was used to identify demographic variables independently associated with survival, for inclusion in the multivariable analysis. Univariable analysis in the discovery cohort identified age at baseline, ethnicity, disease severity (composite physiological index (CPI), and recent infection as significantly associated with mortality. Age and CPI remained independently associated following step-wise elimination. On multivariable analyses adjusting for age and CPI, monocyte count (HR:4.5 (95%CI: 2.02–10.06), p<0.001), CRP (HR: 1.06 (1.03–1.10), p=0.001), and median total white cell count (HR: 1.92 (1.20–3.05), p=0.006) and neutrophil count (HR: 1.74 (1.10–2.76), p=0.018) were significantly associated with shorter survival. Total white cell count was closely related to neutrophil count (Spearman's rho =0.92, p<0.001). Platelet, lymphocyte, eosinophil, basophil counts, and the neutrophil-to-lymphocyte ratio were not associated with survival. In the validation cohort, age, gender, smoking history, and CPI were significantly associated with survival on univariable analysis, with age and CPI remaining as independently associated. The associations with CRP (HR: 1.02 (1.00–1.03), p=0.007), median total white cell count (HR:2.00 (1.20–3.34), p=0.008), and neutrophil count (HR:1.95 (1.17–3.24), p=0.01), but not monocyte count, were replicated in the validation cohort on multivariable analysis, adjusting for age and CPI. CRP and median neutrophil count were independently associated with survival when included together in a multivariable analysis along with age and CPI. All associations remained significant when treatment with corticosteroids and recent infection, at the time of the blood test, were also included in the multivariable analysis along with age and CPI. Higher baseline CRP levels, and neutrophil counts, are significantly associated with increased mortality in patients with fHP.