Association between blood eosinophil count and risk of readmission for patients with asthma: Historical cohort study

PLoS One. 2018 Jul 25;13(7):e0201143. doi: 10.1371/journal.pone.0201143. eCollection 2018.

Abstract

Background: Recent studies have demonstrated an association between high blood eosinophil counts and greater risk of asthma exacerbations. We sought to determine whether patients hospitalized for an asthma exacerbation were at greater risk of readmission if they had a high blood eosinophil count documented before the first hospitalization.

Methods: This historical cohort study drew on 2 years of medical record data (Clinical Practice Research Datalink with Hospital Episode Statistics linkage) of patients (aged ≥5 years) admitted to hospital in England for asthma, with recorded blood eosinophil count within 1 baseline year before admission. We analyzed the association between high blood eosinophil count (≥0.35x109 cells/L) and readmission risk during 1 year of follow-up after hospital discharge, with adjustment for predefined, relevant confounders using forward selection.

Results: We identified 2,613 eligible patients with asthma-related admission, of median age 51 years (interquartile range, 36-69) and 76% women (1,997/2,613). Overall, 835/2,613 (32.0%) had a preadmission high blood eosinophil count. During the follow-up year, 130/2,613 patients (5.0%) were readmitted for asthma, including 55/835 (6.6%) with vs. 75/1,778 (4.2%) without high blood eosinophil count at baseline (adjusted hazard ratio [HR] 1.49; 95% CI 1.04-2.13, p = 0.029). The association was strongest in never-smokers (n = 1,296; HR 2.16, 95% CI 1.27-3.68, p = 0.005) and absent in current smokers (n = 547; HR 1.00, 95% CI 0.49-2.04, p = 0.997).

Conclusions: A high blood eosinophil count in the year before an asthma-related hospitalization is associated with increased risk of readmission within the following year. These findings suggest that patients with asthma and preadmission high blood eosinophil count require careful follow-up, with treatment optimization, after discharge.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Asthma / blood*
  • Asthma / epidemiology*
  • Asthma / therapy
  • Child
  • Child, Preschool
  • Cohort Studies
  • Eosinophils*
  • Female
  • Follow-Up Studies
  • Humans
  • Length of Stay
  • Leukocyte Count
  • Male
  • Middle Aged
  • Patient Readmission*
  • Smoking / epidemiology

Grant support

Data acquisition and analyses were funded by AstraZeneca. This was a collaborative study involving both employees of the sponsor and an independent steering committee. The funder of the study participated in the study design, decision to publish, and preparation of the manuscript. In addition, the funder provided support in the form of salaries for authors TNT, GG, JN, and SR. Employees of the sponsor were part of the study steering committee and participated in the study design. Writing and editorial support was funded by the Observational and Pragmatic Research Institute Pte Ltd (OPRI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.