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Sepsis a 'Hidden Public Health Disaster'

 |  By cclark@healthleadersmedia.com  
   October 27, 2010

Older hospitalized patients who survive sepsis develop lasting, moderate to severe cognitive impairment and functional disability at 3.3 times the rate of patients hospitalized for other reasons, according to a report from University of Michigan researchers.

"The prevalence of moderate to severe cognitive impairment increased 10 percentage points among patients who survived severe sepsis, an odds ratio of 3.34," Theodore Iwashyna MD, University of Michigan assistant professor of internal medicine, and colleagues wrote in Tuesday's issue of the Journal of the American Medical Association.

"The magnitude of these defects was large, likely resulting in a pivotal downturn in patients' ability to live independently."  The researchers added that the problem is so serious and so expensive, that improving prevention and management of sepsis "may warrant a place in the (nation's) broader brain health and disability agendas."

The sepsis study is the first large-scale effort to look at the issue in an older cohort, whose members were drawn from the National Institute on Aging's Health and Retirement Study of 16,772, which includes people over age 50. The study period covered 1998-2005.

Bloodstream infection, said to be the most common cause of critical illness in the U.S., is a major problem for the healthcare system. Those who develop it have twice the risk of death in the following five years as other hospitalized patients. 

The Michigan study shows that those who survive sepsis do not escape unscathed.  The extent of the condition's lasting impact, however, has so far been unclear.

Of these 9,223 underwent baseline cognitive and functional assessments between 1998 and 2004. Of these, 1,520 were hospitalized for severe sepsis and 5,574 were hospitalized for other reasons for comparison.

After being treated for sepsis, survivors developed 1.57 functional limitations when they had none before their hospitalization, they had an increase of 1.5 new limitations on their activities of daily living. For example, nearly one in five developed new problems with shopping or preparing a meal and many had more trouble bathing or toileting themselves.

Other areas that posed additional problems included dressing, eating, using the telephone, managing money, taking medications, or getting into bed. "There was wide range of new difficulties across the array of activities," the authors wrote.

The authors did not say definitively what mechanism deteriorates function or cognition, but they hypothesized some pathways:

  • There could be a direct inflammatory and hypoperfusion mediated degradation of muscle fibers and neurons for patients who have been hospitalized in the intensive care unit.
  • Hypotension or hypoperfusion may directly contribute to brain injury
  • Inflammation, a byproduct of sepsis' pathophysiology, could provoke vascular dementia and Alzheimer's disease.
  • Delirium, common in sepsis, is associated with cognitive decline and long-term cognitive impairment in patients treated with mechanical ventilation.

The authors also discussed the cost to society.

"Cognitive and functional declines of the magnitude seen after severe sepsis are associated with significant increases in caregiver time, nursing home admission, depression, and mortality," they wrote. "These data argue that the burden of sepsis survivorship is a substantial, under recognized public health problem with major implications for patients, families and the healthcare system." 

They added that patients with this severe cognitive impairment "[have] been associated with an additional 40 hours per week of informal care provided by families, analogous to an additional fulltime job."

Iwashyna and colleagues called sepsis "a sentinel event" and said that future research to identify mechanisms leading from sepsis to cognitive impairment and functional disability, as well as interventions to prevent or slow the process, "is especially important now given the aging of the population."

In an editorial in the same issue of the journal, Derek Angus MD, of the CRISMA Center, Critical Care Medicine, University of Pittsburgh School of Medicine, suggested that the problem may represent a "hidden public health disaster."

"The new deficits were relatively more severe among patients who were in better health beforehand, possibly because there was less room for further deterioration among patients who already had poor physical or cognitive function prior to the sepsis episode," he wrote.

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