Whole Picture?

In determining how to most effectively allocate limited resources, it is imperative to accurately define the burden of a given disease. As the number of data sources available for epidemiologic analyses continues to increase, clearly elucidating the relative strengths and weaknesses of these potentially valuable resources is imperative. Evaluating emerging trends in the incidence of specific conditions is vital in most efficiently directing efforts to preventive or therapeutic initiatives. These efforts must, however, be based on the careful examination of the source data as well as the potential impact of external forces. In this context, it is useful to consider the recent work focused on sepsis. Sepsis is the most costly condition in the United States, and costs continue to increase at a rate much higher than for overall hospital stays [1, 2]. Several studies have reported a recent rise in the incidence of sepsis [3, 4]. This work contributed to the development of large-scale campaigns, most notably the Surviving Sepsis Campaign, to improve the diagnosis and treatment of sepsis [5]. Although overall mortality related to sepsis has been increasing due to the general increased incidence of sepsis, the case-fatality rate has been decreasing over a similar period of time. This has been thought to be, in part, an effect of such campaigns. More work is needed to clearly define trends in sepsis incidence and outcomes to evaluate the effectiveness of such interventions. In this light, the work by Gohil and colleagues in this issue of Clinical Infectious Diseases represents an important advance in the field [6]. The authors sought to assess the potential impact of Centers for Medicare and Medicaid Services (CMS) guidance regarding International Classification of Diseases, 9th Revision (ICD-9) coding and Medical Severity Diagnosis Related Group (MSDRG) systems on trends in sepsis. The authors included all adult patients hospitalized in the state of California over a period of 10 years. This comprehensive cohort captured the entire at-risk population, allowing for comprehensive determination of incidence and outcomes. Segmented regression analyses of timeseries data were employed to examine the temporal changes in sepsis incidence and mortality. The authors further strengthened their findings by using logistic regression analysis to identify factors independently associated with the diagnosis of sepsis as well as with mortality. Gohil and colleagues found that the incidence of sepsis increased at a rate higher than would have been predicted by baseline trends and that these increases were temporally associated with both the introduction of CMS sepsis coding guidance and the MS-DRG reimbursement change. Sepsis-related mortality, meanwhile, decreased in a similar fashion. Policy changes were independently associated with both the increase in incidence of sepsis and the decrease in mortality from sepsis. The increase in sepsis incidence was primarily driven by increases in diagnosis of severe sepsis. Additionally, the mean comorbidity score increased over time. Given the high attributable mortality associated with severe sepsis (20%–50%) [7], one would expect mortality rates to increase in parallel. However, the opposite trend was noted. This suggests, as the authors conclude, the “upcapture” not only of sepsis diagnoses but also improved documentation of comorbidities and severity of illness. Sepsis incidence increased despite lack of change in overall admission rates, indicating that these findings are specific to the sepsis diagnosis and not an increase in hospitalizations overall. This article represents a significant advance in elucidating the numerous drivers of sepsis incidence. Most important, the authors reveal the considerable effect of external policy changes on the identified incidence of sepsis, helping to better place recently observed trends in sepsis incidence in context. While acknowledging the demonstrated impact of policy changes, it is also important to note that the incidence of sepsis does appear to be rising, albeit likely at a slower rate than the current trends indicate. This increase in incidence has also been noted in other countries, such as the United Kingdom [8], Croatia [9], and Australia and New Zealand [10]. Several other factors may be at play in the observed increase in sepsis, Received and accepted 4 December 2015; published online 19 January 2016. Correspondence: E. Lautenbach, University of Pennsylvania, 502A Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104 (ebbing@mail.med.upenn.edu). Clinical Infectious Diseases 2016;62(6):704–6 © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com. DOI: 10.1093/cid/civ1023