Population burden of long-term survivorship after severe sepsis in older Americans

Abstract

Objectives: To ascertain the absolute number of Medicare beneficiaries surviving at least 3 years after severe sepsis and to estimate their burden of cognitive dysfunction and disability.

Design: Retrospective cohort analysis of Medicare data.

Setting: All short-stay inpatient hospitals in the United States, 1996 to 2008.

Participants: Individuals aged 65 and older.

Measurements: Severe sepsis was detected using a standard administrative definition. Case-fatality, prevalence, and incidence rates were calculated.

Results: Six hundred thirty-seven thousand eight hundred sixty-seven Medicare beneficiaries were alive at the end of 2008 who had survived severe sepsis 3 or more years earlier. An estimated 476,862 (95% confidence interval (CI) = 455,026-498,698) had functional disability, with 106,311 (95% CI = 79,692-133,930) survivors having moderate to severe cognitive impairment. The annual number of new 3-year survivors after severe sepsis rose 119% during 1998 to 2008. The increase in survivorship resulted from more new diagnoses of severe sepsis rather than a change in case-fatality rates; severe sepsis rates rose from 13.0 per 1,000 Medicare beneficiary-years to 25.8 (P < .001), whereas 3-year case fatality rates changed much less, from 73.5% to 71.3% (P < .001) for the same cohort. Increasing rates of organ dysfunction in hospitalized individuals drove the increase in severe sepsis incidence, with an additional small contribution from population aging.

Conclusions: Sepsis survivorship, which has substantial long-term morbidity, is a common and rapidly growing public health problem for older Americans. There has been little change in long-term case-fatality, despite changes in practice. Clinicians should anticipate more-frequent sequelae of severe sepsis in their patient populations.

Figure 1

New 3-Year and 5-Year Survivors After Severe Sepsis. Figure 4 shows the relative contributions of increasing rates of organ dysfunction per hospitalization with infection, increasing rates of hospitalization with infection, population aging and changes in the 3-year case fatality to these trends.

Figure 2

Hospitalizations and Spending for Severe Sepsis and Acute Myocardial Infarction in Medicare. Spending is for the acute hospitalization only and is not inflation-adjusted.

Figure 3

Case Fatality Rates After Severe Sepsis, by year in which severe sepsis developed. The case fatality rate is the fraction of hospitalizations after which the patient died by the specified time period.

Figure 4

Contributions to the Rising Number of Survivors of Severe Sepsis. This Figure shows the relative number of 3-year survivors who would have been expected had only each given factor changed. Interpretive Example: The aging of the population alone would have resulted in a 5.7% increase in the number of 3-year survivors between 1999 and 2008, had other rates remained the same. The Figure reveals that the most important contributor to the growth in the number of severe sepsis survivors over this decade was the increase in the rate of organ dysfunction per patient hospitalized with infection, not by better survival among patients with severe sepsis.