Understanding the Full Impact of Sepsis: Epidemiology, Definitions and OutcomesPosted on by
Guest Author: Dr. Greg Martin
Professor of Medicine, Emory University
Epidemiology is the study of the distribution and determinants of health-related events and diseases in specified populations. For sepsis, like any other health condition, we want to know how often it occurs, when and where it occurs, who it affects, and what happens during the condition and afterwards.
When studying disease epidemiology, we need a consistent definition. This is an area that remains challenging for sepsis. The earliest attempts at clinically defining sepsis began with the American College of Chest Physicians (ACCP) and Society of Critical Care Medicine (SCCM) consensus definition published in 1992. [1,2] Following that, other studies showed that sepsis occurs with unfortunate frequency and has an immediate and longer-term substantial risk of death.  We further understood the risk factors and the predictors of surviving an episode of severe sepsis, and that the risk of dying is similarly high even in patients with sepsis who did not have laboratory confirmed infection. 
The next major steps in understanding sepsis came from administrative health system data, such as that available through the Centers for Disease Control and Prevention (CDC) or the Agency for Healthcare Research and Quality (AHRQ). Early studies collected data from a few states and examined specific populations, such as severe sepsis, to demonstrate its frequency, lethality and high healthcare costs.  Later studies expanded to the larger group of patients across the full spectrum of sepsis, utilized data representing the entire United States, and characterized additional findings, such as increased cases of sepsis, decreased death rates, and increased frequency among African Americans.  Most recently, we began to understand the long-term risk of death following an episode of sepsis, as well as adverse consequences on our brains, muscles and other functions often leading to disability and reduced quality of life after an episode of sepsis. [7,8]
National and international studies of sepsis have demonstrated the remarkable similarity of disease incidence.  However, variations in approach to identifying sepsis remain, and have led to estimates with a greater range than is desirable,  and served as an important reason for developing a new sepsis definition that was released early in 2016.  We recognize that sepsis results in the death of between 250,000 and 375,000 people each year in the United States, making it among the most common causes of death, so we must continue to investigate the causes of sepsis and focus on at-risk populations to identify truly effective prevention strategies.
CDC’s latest Vital Signs report shows our progress on better understanding sepsis epidemiology, ways to recognize sepsis early, and how we can all play a role in sepsis prevention and recognition. For example, by understanding that 7 in 10 patients with sepsis had recently used healthcare services, it demonstrates the importance of healthcare providers serving as the critical link to sepsis early recognition and treatment. It’s heartening to see so much progress that continues to accelerate, yet each of us still has much work to do in order to address the public health problem of sepsis.
Dr. Martin is Professor of Medicine at Emory University in the Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, where he is active at both Emory Healthcare and in the Grady Health System, both in Atlanta, Georgia. Dr. Martin is involved in designing and conducting research in patients with critical illness, including sepsis, and his work has been funded by the National Institutes of Health (NIH), the Food and Drug Administration (FDA) as well as several philanthropic and healthcare organizations. He serves on the Council / Board of Directors for the Society of Critical Care Medicine and leads the Medical Advisory Board for the non-profit organization, Project Help.
1 ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference: definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. Crit Care Med 1992; 20(6): 864-74.
2 Bone RC, Balk RA, Cerra FB, et al. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. The ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/Society of Critical Care Medicine. Chest 1992; 101(6): 1644-55.
3 Sands KE, et al. Epidemiology of sepsis syndrome in 8 academic medical centers. JAMA 1997; 278: 234-240.
4 Brun-Buisson C, Doyon F, Carlet J, Dellamonica P, Gouin F, Lepoutre A, Mercier JC, Offenstadt G, Régnier B. Incidence, risk factors, and outcome of severe sepsis and septic shock in adults. A multicenter prospective study in intensive care units. French ICU Group for Severe Sepsis. JAMA 1995; 274(12): 968-74.
5 Angus DC, Linde-Zwirble WT, Lidicker J, Clermont G, Carcillo J, Pinsky MR. Epidemiology of severe sepsis in the United States: analysis of incidence, outcome, and associated costs of care. Crit Care Med 2001; 29(7): 1303-10.
6 Martin GS, Mannino DM, Eaton S, Moss M. The epidemiology of sepsis in the United States from 1979 through 2000. N Engl J Med 2003; 348(16): 1546-54.
7 Wang HE, Szychowski JM, Griffin R, Safford MM, Shapiro NI, Howard G. Long-term mortality after community-acquired sepsis: a longitudinal population-based cohort study. BMJ Open 2014;4(1):e004283. doi: 10.1136/bmjopen-2013-004283.
8 Iwashyna TJ, Ely E, Smith DM, Langa KM. Long-term Cognitive Impairment and Functional Disability among Survivors of Severe Sepsis. JAMA 2010; 304(16): 1787-1794. doi:10.1001/jama.2010.1553.
9 Danai P, Martin GS. Epidemiology of sepsis: recent advances. Curr Infect Dis Rep 2005; 7(5):329-34.
10 Gaieski DF, Edwards JM, Kallan MJ, Carr BG. Benchmarking the incidence and mortality of severe sepsis in the United States. Crit Care Med 2013; 41(5): 1167-74. doi: 10.1097/CCM.0b013e31827c09f8.
11 Singer M, Deutschman CS, Seymour C, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA 2016;315(8):801-810. doi:10.1001/jama.2016.0287.