New Tool Gauges C Diff Severity
By Juliann Schaeffer
New research from the United Kingdom focuses on reducing the number of people most affected by the common health care–associated infection Clostridium difficile (C diff) by better predicting those likely to be hit hardest by the bacterium. Experts at the University of Exeter and the Royal Devon and Exeter NHS Foundation Trust recently devised a four-point tool that has helped predict patients’ C diff death risk.
Why It’s Needed
Diarrhea is the most common sign of a C diff infection, though the bacterium also can cause more serious symptoms, such as pseudomembranous colitis (PMC), says Steve Michell, PhD, a senior lecturer in molecular microbiology at the University of Exeter and lead study author. “In 2012, the CDC [Centers for Disease Control and Prevention] estimated that this bacterium caused 14,000 deaths and 337,000 infections in the US,” he says, explaining that a test that could accurately identify which patients are most at risk of dying from complications such as PMC would have great potential for reducing the C diff mortality rate.
Indeed, though rates for many health care–associated infections, such as Staphylococcus aureus and central line–associated bloodstream infections, have been on the decline in recent years, C diff infection rates have remained high. The CDC reports that hospital stays preempted by C diff infections have tripled in the past decade.
A serious issue not only for hospitals but also for nursing homes and outpatient facilities, C diff is a concern familiar especially to geriatricians, as death risk rises with age. According to the CDC, while almost one-half of C diff infections affect patients younger than 65, more than 90% of those who die from the infection are over the age of 65.
According to Michell, the new research findings provide an exciting development and huge potential for deciphering which patients are at risk of dying from C diff infection with one tool that’s simple, accurate, and inexpensive.
How It Works
For this study, researchers collated information retrospectively on a large cohort of 213 patients with confirmed C diff. “We used complex statistical modeling tools to evaluate the relative importance of the variables collated when predicting mortality outcomes,” Foster says.
Researchers then analyzed the data to form this simple clinical prediction tool, which combines four parameters that are generally measured in routine hospital care: respiratory rate, C-reactive peptide, white blood cell count, and albumin. “This was then further evaluated on a different dataset of 158 C diff–positive patients to ensure that results were reproducible, which was found to be the case,” Foster says.
As Michell explains, the tool involves assigning scores to these four easily measurable clinical criteria, depending on their measured levels. “This simple scoring system was developed after analyzing over 100 criteria from each of over 200 patients,” he says. “The analysis and the development of the scoring system used a decision tree classification model, a technique not commonly applied to these kinds of problems. Essentially, this involved getting some mathematicians involved.”
Just how does this test predict a patient’s risk of death from C diff? “This simple clinical tool is able to stratify the risk of death by separating patients into groups according to their score from 0 to 3, with those scoring 0 having the lowest risk of mortality and those scoring a 3 having a very high risk of mortality,” Foster explains.
She says clinical prediction tools such as this one now are becoming more widely used in hospitals “to provide health care workers with an evidence-based way of stratifying risk and guiding appropriate therapy.”
If a tool can distinguish which patients are more likely to suffer complications or more severe symptoms from C diff, then physicians can better determine which patients need a more aggressive—and likely more expensive—type of treatment vs. treating all patients for a higher level of disease that may not be warranted. That makes sense not only with respect to patient care but also with regard to limiting unnecessary costs. “If we can predict those at highest risk of dying from C diff, then we can use different, more invasive treatments from the onset than we would select for those with milder disease,” Foster says.
“The more aggressive drug therapies are not suitable for all patients due to a number of factors, and therefore stratification is appropriate,” she says, adding that the tool should be used by a specialist in a multidisciplinary team as part of the overall evaluation of disease severity and outcome prediction.
Guiding Treatment, Saving Lives
According to Foster, all variables associated with the tool are readily available in the United States. Michell says physicians can easily integrate this tool into their workflow, with awareness being the greatest limiting factor.
Mitchell adds that cost shouldn’t be a prohibiting factor. “The criteria that need to be input into the test are all very basic clinical measurements that would be measured as part of routine care,” he says.
Considering the CDC estimates that C diff infections add at least $1 billion to health care costs each year, it seems any tool that could help the bottom line while potentially saving lives would be a welcome addition to a physician’s arsenal. “The combination of factors combined in the tool is inexpensive. Respiratory rate is a routine nursing observation, and albumin, C-reactive protein, and white cell count are measured in routine clinical care at initial assessment of the patient with C diff,” Foster says. “The tool is an evidence-based way of combining these simple factors to consider mortality risk.”
And both Michell and Foster agree that all patients with confirmed C diff can be assessed with this tool.
But what about patients assessed as being at high risk of developing a C diff infection? According to Foster, it depends on local guidelines, but management could involve “more invasive drugs at an earlier stage, more intensive monitoring, and a multidisciplinary team approach to ensure that any deterioration is detected at an early stage. It may also guide discussions with patient and family regarding prognosis.”
Considering the difficulty involved simply in looking at a patient and trying to determine the severity of his or her C diff infection, Ray Sheridan, MD, a consultant physician at the Royal Devon and Exeter NHS Foundation Trust, says this is a simple tool that could simply but effectively save many lives. “This really simple and quick tool, which any junior doctor could use in the middle of the night quickly and easily, flags up those who need a speedy and intensive treatment regimen or more senior help,” he says. “The quicker we get on with the right treatment for the right patient, the better their chances of recovery are. This is a tool that should be used in every hospital … as soon as possible. If we did so, we would save more lives.”
However, Sheridan is quick to point out that although this tool has great potential for reducing mortality among patients with C diff, one thing it cannot do is reduce the number of people who contract the illness in the first place. In relation to reducing C diff infection rates as a whole, he says more work must be done.
— Juliann Schaeffer is a freelance writer and editor based in Allentown, Pennsylvania.