About 750,000 people in the United States develop sepsis each year. Known in lay terms as blood poisoning, sepsis occurs when the bloodstream is overwhelmed with bacteria, usually in response to the body’s attempt to fight severe infection. Sepsis is a leading cause of death in hospital ICUs, and the elderly are particularly vulnerable to this life-threatening blood infection.
The thinking had been that once the crisis is over, older people who survive sepsis make full recoveries. But new research finds the opposite to be true. A recent study found elderly people had a threefold increase in life-altering cognitive declines after surviving sepsis. Study participants with no history of sepsis showed no increase in risk over the course of the study.
As reported in the October 27 issue of the Journal of the American Medical Association, seniors hospitalized for severe sepsis faced tripled odds of cognitive impairment during the study’s eight-year follow-up. This retrospective analysis indicates that episodes of delirium are associated with an increased rate of disease progression in dementia.
Drawing from the ongoing longitudinal Health and Retirement Study involving some 22,000 Americans, Researchers led by Dr. Jack Iwashyna at the University of Michigan in Ann Arbor, analyzed 1,194 elderly who were hospitalized for severe sepsis between 1998 and 2005, as determined by information on Medicare claims. More than 40 percent of those patients died within 90 days. Among the 516 participants who survived sepsis and had at least one follow-up two years later, 6.1 percent had moderate to severe cognitive impairment when surveyed just prior to sepsis. The prevalence of cognitive decline two years afterward jumped nearly threefold, to 16.7 percent. Based on the new data, it may give rise to some 20,000 new cases of moderate to severe cognitive impairment each year.
In addition to assessing cognition, the researchers also scored, every two years, the participants’ functionality in 11 areas — six daily skills, such as walking and dressing, and five harder tasks like preparing meals and managing finances. Patients with three or fewer deficiencies prior to severe sepsis developed, on average, about 1.5 additional limitations after being hospitalized.
Sepsis is one of the few factors shown to influence rate of disease progression. Inflammation has been implicated in all kinds of health issues, including cognitive decline, and it is a hallmark of severe sepsis. The findings highlight the importance of preventing sepsis in older patients. One of the best strategies for doing this is to vaccinate vulnerable elderly populations against diseases like flu and pneumonia.
Iwashyna TJ, Ely EW, Smith DM, Langa KM. Long-term cognitive impairment and functional disability among survivors of severe sepsis. JAMA. 2010 Oct 27;304(16):1787-94.
Michael S. Rafii, M.D., Ph.D.
Associate Medical Core Director, Alzheimer’s Disease Cooperative Study
This post originally appeared in Alzheimer’s Insights, an ADCS Blog.