Rationale: There is an urgent need for simple, cost-effective prognostic biomarkers for idiopathic pulmonary fibrosis (IPF); biomarkers that show potential include monocyte count.
Objectives: We used pooled data from pirfenidone and interferon gamma-1b trials to explore the association between monocyte count and prognosis in patients with IPF.
Methods: This retrospective pooled analysis included patients (active and placebo arms) from four Phase III, randomized, placebo-controlled trials: ASCEND (NCT01366209), CAPACITY (NCT00287729 and NCT00287716), and INSPIRE (NCT00075998). Outcomes included IPF progression (≥10% absolute decline in percent predicted forced vital capacity, ≥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.
Measurements and Main Results: This analysis included 2067 patients stratified by monocyte count (at baseline: <0.60 GI/L [n=1609], 0.60-<0.95 GI/L [n=408], and ≥0.95 GI/L [n=50]). In adjusted analyses, a higher proportion of patients with monocyte counts of 0.60-<0.95 GI/L or ≥0.95 GI/L versus <0.60 GI/L experienced IPF progression (p=0.016 and p=0.002, respectively), all-cause hospitalization (p=0.030 and p=0.003, respectively), and all cause mortality (p=0.005 and p<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.
Conclusions: 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. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).