Rehospitalizations Following Sepsis: Common and Costly

Abstract

Objective: Although recent studies have shown that 30-day readmissions following sepsis are common, the overall fiscal impact of these rehospitalizations and their variability between hospitals relative to other high-risk conditions, such as congestive heart failure and acute myocardial infarction, are unknown. The objectives of this study were to characterize the frequency, cost, patient-level risk factors, and hospital-level variation in 30-day readmissions following sepsis compared with congestive heart failure and acute myocardial infarction.

Design: A retrospective cohort analysis of hospitalizations from 2009 to 2011.

Setting: All acute care, nonfederal hospitals in California.

Patients: Hospitalizations for sepsis (n = 240,198), congestive heart failure (n = 193,153), and acute myocardial infarction (n = 105,684) identified by administrative discharge codes.

Interventions: None.

Measurements and main results: The primary outcomes were the frequency and cost of all-cause 30-day readmissions following hospitalization for sepsis compared with congestive heart failure and acute myocardial infarction. Variability in predicted readmission rates between hospitals was calculated using mixed-effects logistic regression analysis. The all-cause 30-day readmission rates were 20.4%, 23.6%, and 17.7% for sepsis, congestive heart failure, and acute myocardial infarction, respectively. The estimated annual costs of 30-day readmissions in the state of California during the study period were $500 million/yr for sepsis, $229 million/yr for congestive heart failure, and $142 million/yr for acute myocardial infarction. The risk- and reliability-adjusted readmission rates across hospitals ranged from 11.0% to 39.8% (median, 19.9%; interquartile range, 16.1-26.0%) for sepsis, 11.3% to 38.4% (median, 22.9%; interquartile range, 19.2-26.6%) for congestive heart failure, and 3.6% to 40.8% (median, 17.0%; interquartile range, 12.2-20.0%) for acute myocardial infarction. Patient-level factors associated with higher odds of 30-day readmission following sepsis included younger age, male gender, Black or Native American race, a higher burden of medical comorbidities, urban residence, and lower income.

Conclusion: Sepsis is a leading contributor to excess healthcare costs due to hospital readmissions. Interventions at clinical and policy levels should prioritize identifying effective strategies to reduce sepsis readmissions.

Figure 1

Sepsis Readmission Rates for 2009–2011. The all-cause 30-day readmission rates for sepsis were 20.7%, 20.5%, and 20.1% for 2009, 2010, and 2011, respectively. Approximately 7% of patients were readmitted within 7 days after discharge from an index hospitalization for sepsis. Within 90 days of an index hospitalization, over 30% of patients were readmitted. The rate of 7, 14, 30, and 90-day readmissions decreased slightly from 2009 to 2011.

Figure 2

Variation of Adjusted 30-Day Readmission Rates in California Hospitals for Sepsis. The risk and reliability adjusted proportion of 30-day readmissions at each hospital ranged from 11.0% to 39.8% (median 19.9%, IQR 16.1–26.0%) for sepsis (black triangle), 11.3% to 38.4% (median 22.9%, IQR 19.2 – 26.6%) for CHF (light gray diamond), and 3.6% to 40.8% (median 17.0%, IQR 12.2–20.0%) for AMI (dark gray square). The 30-day readmission rates were adjusted for age and the number of medical co-morbidities. The error bars indicate 95% confidence intervals. *N=287 for AMI, 328 for CHF, and 325 for sepsis

Figure 3

Sepsis Readmission Diagnosis Categories. Infections were the most common diagnosis category on 7, 14, 30, and 90-day readmissions and comprised nearly 60% of the cases. Pulmonary diagnoses were the second most common cause, comprising 12–16% of cases. The proportion of readmissions caused by infections remained stable over the first 90 days after the index hospitalization, while pulmonary causes decreased over that time.