February 15, 2012 (Houston, Texas) — People who live in areas where 20% to 40% of the population live in poverty are at increased risk for bloodstream infection if they become critically ill and end up in the intensive care unit (ICU), according to research presented here at the Society of Critical Care Medicine 41st Critical Care Congress.
"There is literature in psychoimmunology and the postulate is that high stress leads to depression of the innate immune response," senior author Kenneth Christopher, MD, from Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, told Medscape Medical News at a poster session.
Dr. Kenneth Christopher
"Poverty in terms of socioeconomic measures appears to be associated with bloodstream infections that are associated temporally with an ICU admission. It appears that if you come from a neighborhood with a very high poverty rate, you may be more susceptible to bloodstream infection," he said.
In the observational cohort study, led by Mallika Mendu, MD, from Brigham and Women's Hospital, the researchers looked at 14,657 patients 18 years and older who received critical care from 1997 to 2007 at 2 hospitals in Boston.
Data were obtained from the US Census and hospital administrative records. Blood cultures obtained 48 hours before and 48 hours after critical care was started were used to determine bloodstream infection. None of the infecting organisms were isolated from the ICU, Dr. Christopher noted.
After adjustment for age, sex, race, medical or surgical patient type, Deyo-Charlson Index, total parenteral nutrition (TPN), hematocrit, white blood cell count, creatinine, and blood urea nitrogen, the researchers found that neighborhood poverty rate was a strong predictor of risk for bloodstream infection.
Compared with patients from neighborhoods where the poverty rate was less than 5%, those from neighborhoods with a 20% to 40% poverty rate had a 26% increased risk for bloodstream infection (odds ratio [OR], 1.26; 95% confidence interval [CI], 1.09 to 1.47; P = .002).
Patients who lived where the neighborhood poverty rate was higher than 40% had a 49% increased risk for bloodstream infection (OR, 1.49; 95% CI, 1.05 to 2.11; P = .03).
Neighborhood poverty was not associated with mortality.
"I think this illustrates that patients who are poor are stressed for a long period of time and have a blunted immune system. It's not because of access to care, because they are in the hospital and have care access, and I don't think it's because of starting antibiotics later than sooner. We also controlled for things like nutrition, diabetes, and other comorbidities," said Dr. Christopher.
Commenting on this study for Medscape Medical News, Charudutt Paranjape, MD, from Akron General Hospital in Ohio, who was not part of the study, said that it is important to know why poorer patients are prone to bloodstream infections.
"Were they sicker on admission? Were they malnourished? I know the investigators looked at TPN, but sometimes patients get a [peripherally inserted central catheter] line or central line without having TPN, especially in the ICU. Were the central lines placed more emergently, so that there might be less sterility, leading to more chance of infection? This is an interesting topic," he said.
Dr. Christopher and Dr. Paranjape have disclosed no relevant financial relationships.
Society of Critical Care Medicine (SCCM) 41st Critical Care Congress: Abstract 501. Presented February 6, 2012.
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