Sepsis Mortality Rates Depend on Data Source Used, CDC Says

Nicola M. Parry, DVM

April 08, 2016

Estimates of the rate of sepsis-related mortality vary widely, depending on what source of public health data is evaluated, a new study suggests. The report highlights the need for a reliable sepsis surveillance definition based on objective clinical data.

Lauren Epstein, MD, from the National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, and colleagues published the results of their study in the April 8 issue of the Morbidity and Mortality Weekly Report.

A reliable sepsis surveillance definition would allow clinicians "to more accurately track national sepsis trends and enable objective assessment of the impact of efforts to increase sepsis awareness and prevention," the authors write.

Sepsis is a serious, life-threatening clinical condition caused by a dysregulated immune response to infection. However, its diagnosis is not solely laboratory-based, but requires careful consideration of a combination of evidence of infection and clinical criteria.

According to the authors, "[b]oth death certificates and health services utilization data (administrative claims) have been used to assess sepsis incidence and mortality, but estimates vary depending on the surveillance definition and data source."

To highlight this difference, Dr Epstein and colleagues conducted a retrospective analysis to estimate the rate of sepsis-associated mortality based on evaluation of death certificate data and to compare it with an estimate based on evaluation of administrative codes.

They analyzed death certificate data from the National Vital Statistics System for the period from 1999 to 2014 and identified 2,470,666 cases (accounting for 6% of all deaths) in which sepsis was listed among the causes of each patient's death. In 22% of these cases, sepsis was identified as the underlying cause of death. The annual number of sepsis-related deaths also increased 31% (from 139,086 to 182,242) from 1999 to 2014.

Next, they compared these data with those from a previously published report that used four established methods to estimate rates of sepsis-associated mortality based on administrative claims data from hospital discharges reported in the Nationwide Inpatient Sample, Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality. This earlier report had shown that annual estimates of sepsis-related mortality varied, depending on the method used, and ranged from 168,000 to 381,000.

The authors emphasize that this annual range of sepsis-related mortality based on administrative claims data was 15% to 140% higher than that obtained using death certificate data for the corresponding period from 2004 to 2009 (range, 146,000 - 159,000).

Although death certificates and administrative claims data are important sources of public health information, "recognizing the limitations of both methods for generating sepsis-related mortality estimates is important," the authors note.

For example, because of misunderstandings about how to complete death certificates, as well as underestimation of the importance of sepsis as a cause of death, certified causes of death may be inaccurate in many cases. In addition, administrative claims data only include sepsis-related deaths that occur within healthcare facilities and fail to capture the approximately 15% of sepsis-related deaths that occur outside of these facilities.

"Current efforts focused on evaluating linkages of administrative claims data derived from inpatient medical records with death certificates will improve understanding of how mortality estimates from death certificates and administrative claims data should be interpreted," the authors conclude.

The authors have disclosed no relevant financial relationships.

Morb Mortal Wkly Rep. 2016;65:342-345. Full text


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