title: Proposing an empirically justified reference threshold for blood culture sampling rates in intensive care units.
abstract: Early and appropriate blood culture sampling is recommended as a standard of care for patients with suspected bloodstream infections (BSI) but is rarely taken into account when quality indicators for BSI are evaluated. To date, sampling of about 100 to 200 blood culture sets per 1,000 patient-days is recommended as the target range for blood culture rates. However, the empirical basis of this recommendation is not clear. The aim of the current study was to analyze the association between blood culture rates and observed BSI rates and to derive a reference threshold for blood culture rates in intensive care units (ICUs). This study is based on data from 223 ICUs taking part in the German hospital infection surveillance system. We applied locally weighted regression and segmented Poisson regression to assess the association between blood culture rates and BSI rates. Below 80 to 90 blood culture sets per 1,000 patient-days, observed BSI rates increased with increasing blood culture rates, while there was no further increase above this threshold. Segmented Poisson regression located the threshold at 87 (95% confidence interval, 54 to 120) blood culture sets per 1,000 patient-days. Only one-third of the investigated ICUs displayed blood culture rates above this threshold. We provided empirical justification for a blood culture target threshold in ICUs. In the majority of the studied ICUs, blood culture sampling rates were below this threshold. This suggests that a substantial fraction of BSI cases might remain undetected; reporting observed BSI rates as a quality indicator without sufficiently high blood culture rates might be misleading.
authors.affiliation: Department of Epidemiology, Helmholtz Centre for Infection Research, Braunschweig, Germany German Center for Infection Research, Hannover-Braunschweig Site, Hannover-Braunschweig, Germany andre.karch@helmholtz-hzi.de.
authors.forename: André
authors.identifier: http://orcid.org/0000-0003-3014-8543
authors.initials: A
authors.lastname: Karch
authors.affiliation: Department of Epidemiology, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Castell
authors.affiliation: Institute of Hygiene and Environmental Medicine, German National Reference Center for the Surveillance of Healthcare-Associated Infections, Charité University Medicine Berlin, Berlin, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Schwab
authors.affiliation: Institute of Hygiene and Environmental Medicine, German National Reference Center for the Surveillance of Healthcare-Associated Infections, Charité University Medicine Berlin, Berlin, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Geffers
authors.affiliation: Department of Epidemiology, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Hannah
authors.initials: H
authors.lastname: Bongartz
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Centre for Sepsis Control and Care, Jena University Hospital, Jena, Germany Centre for Clinical Studies, Jena University Hospital, Jena, Germany.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Brunkhorst
authors.affiliation: Institute of Hygiene and Environmental Medicine, German National Reference Center for the Surveillance of Healthcare-Associated Infections, Charité University Medicine Berlin, Berlin, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Gastmeier
authors.affiliation: Department of Epidemiology, Helmholtz Centre for Infection Research, Braunschweig, Germany German Center for Infection Research, Hannover-Braunschweig Site, Hannover-Braunschweig, Germany Hannover Medical School, Hannover, Germany.
authors.forename: Rafael T
authors.initials: RT
authors.lastname: Mikolajczyk
mesh_terms: D001769:Blood / Q000382:microbiology*; D003422:Critical Care / Q000379:methods*; D062665:Epidemiological Monitoring; D006801:Humans; D007362:Intensive Care Units; D008828:Microbiological Techniques / Q000379:methods*; D018805:Sepsis / Q000175:diagnosis*; D013048:Specimen Handling / Q000379:methods*