The study utilized data from 1979 to 2001 from the National Hospital Discharge Survey (NHDS) and the Surveillance, Epidemiology, and End Results (SEER) databases. Conducted by Emory physicians Greg Martin, MD, MSc, Marc Moss, MD, and Pajman Danai, MD from the Division of Pulmonary, Allergy and Critical Care, and by David Mannino, MD, of the University of Kentucky, Division of Pulmonary and Critical Care Medicine, the research is the first to present nationally representative longitudinal data for the impact of sepsis among cancer patients and to examine gender and racial disparities in this condition.
The NHDS database from the years 1979 to 2001 included 854 million hospitalizations, of which 76.7 million involved a co-existing diagnosis of malignancy, and nearly 11 million involved sepsis. Sepsis occurred in 2.3 percent of all the cancer patients, or 1.7 million patients. According to the study, during the 23-year study period, the number of sepsis cases in patients with cancer increased from 24,150 in 1979 to 87,160 in 2001, representing an increase of 261 percent during the study period. Of the sepsis patients with a history of cancer, gastrointestinal malignancies were most common at 24.4 percent, followed by lung (20 percent), lymphoma (14.1 percent), prostate (9.3 percent), and breast cancers (8.8 percent). Patients with pancreatic cancer were found to have the highest incidence of sepsis, even greater than for leukemia.
Sepsis occurs when the intended protective and reparative immune response becomes exaggerated and causes problems throughout the body, such as acute renal failure and lung failure. Previous Emory studies have concluded that sepsis is an increasingly common and life-threatening condition across the United States, having risen to the tenth leading cause of death overall in this country, and that it afflicts persons of all ages.
In the study, Emory investigators conclude that cancer is a strong independent predictor of mortality from sepsis due to compromised immune systems. The use of chemotherapy, radiation, or other immune modulating therapy employed to combat the underlying malignancy are some of the reasons for patients' increased susceptibility to sepsis.
Dr. Martin says that although sepsis can occur in anyone, there are certain factors that make sepsis more likely.
"People of older age are more likely to develop sepsis, and certain co-morbid medical conditions, such as HIV, are known to increase the risk of sepsis because of their influence on normal immune function," he said. "There is very little data on how sepsis affects cancer patients, although physicians generally feel that cancer patients are more susceptible to sepsis because the normal immune system is altered, either because of the cancer itself or because of chemotherapy. Based on the data in this paper, we now know that cancer is clearly one of those conditions that increases the risk for sepsis--in this case by 10 times."
Dr. Martin also says that other findings from the research are important for physicians who take care of either cancer patients or sepsis patients. Care of sepsis patients requires antibiotics, usually prescribed based upon the suspected source of infection. For cancer patients, the source of sepsis is highly related to the type of cancer. Lung cancer patients, for instance, are more likely to get respiratory infections as a cause of sepsis, while patients with prostate cancer are more likely to develop urinary infections and patients with gastro-intestinal malignancies are more likely to develop abdominal sepsis.
"This is potentially useful for physicians in both preventing infections that may cause sepsis, and in treating cancer patients who present with sepsis," Dr. Martin explained.
The case-fatality rate for sepsis was highest in the study for patients with lung cancer, at 40 percent, compared to approximately 26 percent for patients with other types of cancer, such as breast, prostate and skin cancer.
The study also reveals that sepsis incidence rates are higher among cancer patients than among patients with other conditions commonly considered to increase the risk of sepsis. Out of 100,000 cancer patients in the U.S., for example 1,075 developed sepsis, compared to 1,051 per 100,000 patients with HIV/AIDS or 701 per 100,000 patients with diabetes. Sepsis patients with cancer overall had a 55 percent greater risk of dying than sepsis patients without cancer, and after adjusting for other factors that may influence the risk of dying (such as the type of infection or severity of illness), sepsis patients with cancer were twice as likely to die compared to sepsis patients without cancer.
"There is a striking increase in the risk of dying with sepsis that appears to be directly attributable to the diagnosis of cancer," Dr. Martin says.
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