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Clinical and epidemiological variability in severe sepsis: an ecological study
  1. J Priyanka Vakkalanka1,2,
  2. Karisa K Harland1,2,
  3. Morgan B Swanson1,2,
  4. Nicholas M Mohr1,2,3
  1. 1 Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
  2. 2 Department of Epidemiology, University of Iowa College of Public Health, Iowa City, Iowa, USA
  3. 3 Department of Anaesthesia, Division of Critical Care, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
  1. Correspondence to J Priyanka Vakkalanka, Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA; vakkalanka{at}


Background To assess clinical and epidemiological trends of severe sepsis.

Methods Ecological study of patients presenting to the emergency department with severe sepsis or septic shock between 2005 and 2013. Patients were identified using the state-wide hospital administrative database. Key outcomes included incidence rates (IRs) and mortality rates (per 1000 population) by age and medically underserved areas (MUAs), sepsis case fatality rate (deaths per 100 sepsis cases), and proportions of transfer and comorbidities.

Results There were 154 019 sepsis cases identified. In 2005, 85+ yo in non-MUAs had a 44% increase in IR compared with those in MUAs, and this difference rose to 74% by 2013. Mortality rates were 1.6 (95% CI 1.3 to 1.8) times greater among 85+ yo in non-MUAs. Mortality rates increased by 1.8% annually, while the sepsis case fatality rate decreased by 7.7%. The proportion of transfer among sepsis cases decreased by 2.1% per year (3.8% in non-MUAs, 0.7% in MUAs).

Conclusions Sepsis incidence varies geographically, and access to healthcare is one proposed mechanism that may explain heterogeneity. Over time, we may be capturing higher acuity sepsis cases with better recognition and management, as well as observing differential diagnostic coding documentation by location.

  • epidemiology of aging
  • geography
  • inequalities
  • mortality
  • infection

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  • Contributors JPV, NMM and KKH designed the study. JPV and KKH provided expertise in the interpretation of the data. JPV and KKH were responsible for managing the data and provided oversight of statistical analyses. JPV and KKH had full access to the data set and analysed the data. JPV, KKH and MBS drafted the manuscript, and all authors contributed substantially to its revision. JPV takes responsibility for the paper as a whole.

  • Funding This work was supported by the Emergency Medicine Foundation, the University of Iowa Department of Emergency Medicine and the University of Iowa Institute for Clinical and Translational Science.

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval University of Iowa.

  • Provenance and peer review Not commissioned; externally peer reviewed.