Septic Shock Surveillance Should Be Based on Clinical Data, Not Billing Codes

New study in CHEST found that analyzing medical data instead of billing codes gave a more accurate picture of septic shock trends

Glenview, IL, February 13, 2017

Sepsis is a major public health problem and the focus of national quality measures and performance improvement initiatives. Understanding what is happening with sepsis rates and outcomes is thus an area of great importance. However, tracking sepsis rates and outcomes is challenging because it is a heterogeneous syndrome without a definitive “gold standard” test. In the February issue of CHEST, investigators compared the effectiveness of claims-based surveillance using ICD-9 codes with clinical-based data and specific diagnostic parameters. Their findings suggest that surveillance based on clinical criteria is a more reliable way to track cases of septic shock.

“Our results underscore the challenges in tracking sepsis and septic shock using diagnosis billing codes, which is the current method typically used for epidemiologic studies as well as quality measures. We show, however, that an alternative surveillance method using clinical data is feasible and may provide more reliable estimates of trends over time,” explained co-lead investigator Chanu Rhee, MD, MPH, Department of Population Medicine, Harvard Medical School/Harvard Pilgrim Health Care Institute and Division of Infectious Diseases, Brigham and Women’s Hospital, Boston, MA.

Researchers examined data from 27 academic hospitals between 2005-2014 and looked for cases of septic shock using two different methods: claims data and clinical data. For claims-based surveillance, they located cases with septic shock-related ICD-9 billing codes. For clinical surveillance, they looked for patients who received concurrent vasopressors, blood culture orders, and antibiotics. When compared, they showed the sensitivity was higher for the clinical criteria than for the claims (74.8 percent versus 48.3 percent) relative to medical record reviews, but positive predictive value was comparable (83 percent versus 89 percent).

The greatest differences the team found came when looking at septic shock trends over time. Investigators found that with clinical data, septic shock cases rose from 12.8 to 18.6 per 1,000 hospitalizations, while mortality declined from 54.9 percent to 50.7 percent. Meanwhile, the results from ICD-9 codes show a much larger jump, from 6.7 to 19.3 cases per 1,000 hospitalizations, while mortality decreased from 48.3 percent to 39.3 percent.

Annual septic shock incidence trends at 27 U.S. academic medical centers using the clinical surveillance definition versus ICD-9 codes, 2005-2014.

“The incidence of patients with discharge codes or clinical markers indicative of treated septic shock steadily rose during the 10-year surveillance period, and in-hospital mortality for this population declined,” stated Dr. Rhee. “The magnitude of these trends was considerably less when using clinical data compared with claims codes. Clinician record reviews suggested that clinical surveillance definitions for septic shock provide greater sensitivity and comparable positive predictive value than billing codes.”

While both datasets showed an increase in cases and a decline in mortality, the clinical numbers suggest this shift has been much less dramatic than previously believed. “Tracking trends in septic shock incidence and outcomes is critical to informing the allocation of health care resources and interpreting the impact of sepsis prevention and treatment initiatives,” said Dr. Rhee. “However, it remains unclear whether claims-based reports of dramatic rises in sepsis and septic shock incidence and declining case fatality rates reflect more infections, better recognition, more aggressive treatment, and/or more comprehensive coding.”

Investigators also observed that other factors may influence the statistics about septic shock mortality. As more patients opt to leave the hospital setting for end-of-life care at a hospice, the number of hospital deaths from septic shock is declining. “Not accounting for this evolving societal preference can exaggerate the overall impression of improving outcomes,” noted Dr. Rhee.

While septic shock continues to be an important area of focus for practitioners and public health experts, tracking clinical data may prove to be a better way to accurately observe septic shock trends. “The imperfect sensitivity of codes as well as our clinical surveillance definition suggest that both methods may still underestimate the true burden of septic shock,” concluded Dr. Rhee. “However, surveillance-based clinical data may allow for more reliable estimates of septic shock burden and trends compared with administrative data.”

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Notes for editors
The article is “Estimating Ten-Year Trends in Septic Shock Incidence and Mortality in United States Academic Medical Centers Using Clinical Data,” by Sameer S. Kadri, MD, MS; Chanu Rhee, MD, MPH; Jeffrey R. Strich, MD; Megan K. Morales, MD; Samuel Hohmann, PhD; Jonathan Menchaca, BA; Anthony F. Suffredini, MD; Robert L. Danner, MD; and Michael Klompas, MD, MPH (http://dx.doi.org/10.1016/j.chest.2016.07.010) published in CHEST, volume 151, issue 2 (February 2017) by Elsevier.

Full text of this article and interviews with the authors are available to credentialed journalists upon request; contact Andrea Camino, American College of Chest Physicians at +1 224-521-9513 or acamino@chestnet.org.

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CHEST
, the official publication of the American College of Chest Physicians, features the best in peer-reviewed, cutting-edge original research in the multidisciplinary specialties of chest medicine: pulmonary, critical care and sleep medicine; thoracic surgery; cardiorespiratory interactions; and related disciplines. Published since 1935, it is home to the highly regarded clinical practice guidelines and consensus statements. Readers find the latest research posted in the Online First section each week and access series that provide insight into relevant clinical areas, such as Recent Advances in Chest Medicine; Topics in Practice Management; Pulmonary, Critical Care and Sleep Pearls; Ultrasound Corner; Chest Imaging and Pathology for Clinicians; and Contemporary Reviews. Point/Counterpoint Editorials and the CHEST Podcasts address controversial issues, fostering discussion among physicians. www.chestnet.org/Publications/CHEST-Publications/CHEST-Journal

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Media contact
Andrea Camino
American College of Chest Physicians (CHEST)
+1 224-521-9513
acamino@chestnet.org