Impact of Policies on the Rise in Sepsis Incidence, 2000–2010

BACKGROUND: Sepsis hospitalizations have increased dramatically in the last decade. It is unclear whether this represents an actual rise in sepsis illness or improved capture by coding. We evaluated the impact of Centers of Medicare and Medicaid Services (CMS) guidance after newly introduced sepsis codes and medical severity diagnosis-related group (MS-DRG) systems on sepsis trends. METHODS: In this retrospective cohort study of California hospitalizations from January 2000 to December 2010, sepsis was identified by International Classification of Diseases, Ninth Revision (ICD-9) coding (Dombrovskiy method). Sepsis-associated mortality rates were calculated. Logistic regression models evaluated variables associated with sepsis and mortality. Segmented regression time series analysis assessed changes in sepsis frequency for (1) baseline (January 2000 to September 2003); (2) post-CMS guidelines on sepsis coding (October 2003 to September 2007); and (3) after the introduction of MS-DRG (October 2007 to December 2010). RESULTS: Annual hospitalizations with sepsis diagnoses tripled within a decade, from 21.1 to 59.9 cases per 1000 admissions, with a 2.8- and 2.0-fold increase in severe and nonsevere sepsis, respectively, whereas annual admissions remained unchanged and sepsis-associated mortality decreased. Greatest increases were seen for severe sepsis present on admission (3.8-fold increase). Increases in sepsis were temporally correlated with CMS coding guidance and MS-DRG introduction after adjustment for comorbidity and other factors. CONCLUSIONS: Sepsis rate increases were associated with introduction of CMS-issued guidance for new sepsis ICD-9 coding and MS-DRGs. Coding artifact ("up-capture" of less severely ill septic patients) may be contributing to the apparent rise in sepsis incidence and decline in mortality. Epidemiologic trends based on administrative data should account for policy-related effects.