Monocyte Count as a Prognostic Biomarker in Patients with Idiopathic Pulmonary Fibrosis.

Abstract

<b>Rationale:</b> There is an urgent need for simple, cost-effective prognostic biomarkers for idiopathic pulmonary fibrosis (IPF); biomarkers that show potential include monocyte count. <b>Objectives:</b> We used pooled data from pirfenidone and IFNγ-1b trials to explore the association between monocyte count and prognosis in patients with IPF. <b>Methods:</b> This retrospective pooled analysis included patients (active and placebo arms) from the following four phase III, randomized, placebo-controlled trials: ASCEND (NCT01366209), CAPACITY (NCT00287729 and NCT00287716), and INSPIRE (NCT00075998). Outcomes included IPF progression (≥10% absolute decline in FVC% predicted, ≥50 m decline in 6-minute-walk distance, or death), all-cause hospitalization, and all-cause mortality over 1 year. The relationship between monocyte count (defined as time-dependent) and outcomes was assessed using bivariate and multivariable models. <b>Measurements and Main Results:</b> This analysis included 2,067 patients stratified by monocyte count (at baseline: <0.60 × 10⁹ cells/L [<i>n</i> = 1,609], 0.60 to <0.95 × 10⁹ cells/L [<i>n</i> = 408], and ≥0.95 × 10⁹ cells/L [<i>n</i> = 50]). In adjusted analyses, a higher proportion of patients with monocyte counts of 0.60 to <0.95 × 10⁹ cells/L or ≥0.95 × 10⁹ cells/L versus <0.60 × 10⁹ cells/L experienced IPF progression (<i>P</i> = 0.016 and <i>P</i> = 0.002, respectively), all-cause hospitalization (<i>P</i> = 0.030 and <i>P</i> = 0.003, respectively), and all-cause mortality (<i>P</i> = 0.005 and <i>P</i> < 0.001, respectively) over 1 year. Change in monocyte count from baseline was not associated with any of the outcomes over 1 year and did not appear to be affected by study treatment. <b>Conclusions:</b> In patients with IPF, elevated monocyte count was associated with increased risks of IPF progression, hospitalization, and mortality. Monocyte count may provide a simple and inexpensive prognostic biomarker in IPF.