The course of idiopathic pulmonary fibrosis (IPF) is characterized by variable patterns of disease progression. The red cell distribution width (RDW) is a parameter that is routinely reported with all CBC counts. We sought to test the prognostic usefulness of this parameter in a well-defined cohort of patients with IPF.
CBCs, demographics, and pulmonary function data from patients with IPF evaluated between January 1997 and June 2011 were collated. Patient outcomes were ascertained from the program’s database and the Social Security Death Index.
There were 319 patients with IPF evaluated in whom baseline CBCs were available. The range in the RDW was 11.9 to 21.9 (median 14.1). There were 228 subjects with RDW values ≤ 15 (normal) and 91 patients with RDW values > 15. Patients with normal RDW values had a median survival of 43.1 months compared with 16.3 months for those whose RDW was > 15 (P = .001). There were 198 patients with available serial RDW data. Those patients who had a change in the RDW of less or greater than +0.010/mo had median survivals of 43.0 and 23.9 months, respectively (P = .0246).
The RDW is a readily available laboratory test result that may provide important, independent prognostic information at baseline and follow-up in patients with IPF. Further studies are warranted to validate this as a biomarker for IPF outcomes, as well as to define the biologic basis for this association.