Article open access publication

Associations between biomarkers at discharge and co-morbidities and risk of readmission after community-acquired pneumonia: a retrospective cohort study

European Journal of Clinical Microbiology & Infectious Diseases, Springer Nature, ISSN 1435-4373

Volume 37, 6, 2018

DOI:10.1007/s10096-018-3224-8, Dimensions: pub.1101835046, PMC: PMC5948264, PMID: 29600325,



  1. (1) Nordsjællands Hospital, grid.414092.a, Capital Region
  2. (2) University of Copenhagen, grid.5254.6, KU
  3. (3) Hannover Medical School, grid.10423.34
  4. (4) University Hospital Frankfurt, grid.411088.4
  5. (5) Gentofte Hospital, grid.411646.0, Capital Region







To investigate whether hemoglobin, white blood cell count (WBC), urea, sodium, albumin, and C-reactive protein at discharge in patients hospitalized for community-acquired pneumonia (CAP) are associated with 30-day readmission. This study is a retrospective cohort study, which included all adult patients discharged after hospitalization for CAP from three Danish hospitals between January 2011 and July 2012. The outcome was all-cause, unplanned, 30-day readmission. Biomarker concentrations at discharge were transformed into binary variables by using either upper or lower quartiles as cut-off; the upper quartile was used for WBC, urea, and C-reactive protein, and the lower quartile was used for hemoglobin, sodium, and albumin. The study population consisted of 1149 patients. One hundred eighty-four (16.0%) patients were readmitted. Independent risk factors of readmission were WBC ≥ 10.6 cells × 109/L (hazard ratio 1.50; 95% CI, 1.07-2.11) and albumin <32 g/L (hazard ratio 1.78; 95% CI, 1.24-2.54) at discharge and the presence of ≥ 2 co-morbidities (hazard ratio 1.74; 95% CI, 1.15-2.64). When WBC, albumin, and co-morbidities were combined into a risk-stratification tool, there was a step-wise increase in risk of readmission for patients with 1, 2, or 3 risk factors with hazard ratios of 1.76 (95% CI, 1.25-2.49), 2.59 (95% CI, 1.71-3.93), and 6.15 (95% CI 3.33-11.38), respectively. WBC ≥ 10.6 cells × 109/L and albumin < 32 g/L at discharge and the presence of ≥ 2 co-morbidities were independently associated with increased risk of 30-day readmission.


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