Change in Guidelines Double Ability to Predict C. Diff Mortality

As the most common health care-associated infection in the United States, a new guideline that improves clinicians’ ability to predict clostridioides difficile (C. diff) mortality could change treatment approaches for the bacterial infection.

C. diff is notoriously difficult to identify and treat, causing an estimated 12,800 deaths each year, according to a team of researchers from the University of Houston. In 2017, the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA) updated their guidelines for assessing patients and the severity of their infections. Now, new research from the University of Houston College of Pharmacy has proven that these specific updates were effective.

“Whenever changes to national guidelines are based on expert opinion only, that is an opportunity to do a research project to see if those experts were correct,” said Kevin Garey, PharmD, MS, FASHP, professor of pharmacy practice at the UH College of Pharmacy, in a press release.

The change in guidelines revolved around how to assess damage to the kidneys caused by fluid loss associated with severe C. diff infection. The damage can be detected when blood levels show increased creatinine, a waste product formed when creatine in muscles breaks down. A normal range for serum creatinine (SCr) is generally below 1 milligram per deciliter of blood (1mg/dL), according to the study authors.

Garey said there are several ways to use creatinine to determine whether someone has kidney damage, although a common approach is to use at least a 50% increase in creatinine from a previous measurement. An obstacle, however, is that the prior measurement does not exist in many cases.

IDSA and SHEA recognized this problem in the new guidelines and chose to use a creatinine value above 1.5 mg/dL at the time of infection to indicate kidney damage. However, this change was based on expert opinion and had not been tested scientifically. Garey and a team of UH pharmacy students, postdoctoral researchers, and research scientists, and faculty aimed to prove whether the criteria were valid, and they found that the new severity classification was successful.

The new severity assessment allows clinicians to understand when they have a severely ill patient at high risk for mortality and tailor treatment accordingly. The team studied 705 adult patients hospitalized with C. diff infection in several hospitals around Houston.

“Using the new single creatinine measurement above 1.5 to define [C. diff infection] severity was fourfold more predictive in identifying patients likely to die during their hospitalization,” Garey said in the press release. “When combined with increased white blood cell count, another severity predictor, the newly revised severity predictor was twofold better at predicting mortality.”

“The revised SCr criterion was independently associated with increased odds of mortality when analyzed as a single criterion and combined with [white blood cell counts] as per the IDSA-SHEA severity guidelines,” Garey said in the press release.

REFERENCE

Ability to Predict C-Diff Mortality Nearly Doubled with New Guidelines [news release]. University of Houston; December 9, 2020. https://uh.edu/news-events/stories/2020/december-2020/12092020-kevin-garey-c-diff-guidelines-examined-approved.php. Accessed March 9, 2021.