Jim Kling

September 12, 2013

DENVER — Rates of Clostridium difficile infection (CDI) nearly doubled in a decade in US hospitals, results of a new survey show. The diarrhea-causing bacteria, which often occur as a complication of treatment with antibiotics, affected about 2.2 million people during a 10-year period.

These data are "the first I'm aware of to look at trends in mortality and length of hospital stay among patients with CDI," said Kelly Daniels, PharmD, a graduate student at the University of Texas at Austin.

Dr. Daniels presented the research here at the 53rd Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).

Dr. Daniels and her team conducted a retrospective analysis of people aged 18 years and older who were discharged from the hospital with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code for CDI. Their data came from the US National Hospital Discharge Surveys.

The researchers used a multivariable logistic model to compare mortality in primary and secondary CDI, and a linear regression model to compare length of hospital stay for primary and secondary CDI.

The median age of the 2.2 million hospitalized patients with CDI was 75 years (interquartile range, 61 - 83).

More Infections

Of the hospitalized patients, 32.5% had a primary diagnosis of CDI, and 67.5% had a secondary diagnosis.

The median hospital stay overall was 8 days (range, 4 - 14), but it was shorter for patients with a primary diagnosis of CDI than for patients with a secondary diagnosis (5 vs 9 days; risk ratio [RR], 13.3; 95% confidence interval [CI], 9.0 - 18.5).

The mortality rate peaked in 2003, at 8.7%, and hit its lowest in 2009, at 5.6%. The overall mortality rate for the study period was 7.1%, but it was lower for patients with a primary diagnosis of CDI than for patients with a secondary diagnosis (3.3% vs 8.8%; RR, 1.8; 95% CI, 1.76 - 1.84).

The mortality findings are encouraging, according to Dr. Daniels. "We only found a slight increase in mortality, which was surprising, because some earlier studies showed a pretty dramatic increase in mortality in patients with CDI. Our study shows that it's starting to level off."

Fewer Deaths

This suggests that physicians have learned how to better treat patients with CDI, but the increased incidence is a concern. "The study gives clinicians and researchers an idea of the burden of disease in our hospitals, which can help to push forward implementation of prevention initiatives and public policies that can help reduce the incidence of these infections. There's more work to be done on prevention," said Dr. Daniels.

One important limitation of the study is that more sensitive methods have been adopted to detect CDI during the past decade, so the increase in incidence might be the result of better detection.

The report is consistent with other studies, according to session moderator Clifford McDonald, MD, a medical epidemiologist at the Centers for Disease Control and Prevention (CDC) in Atlanta. He noted that newer projections from the Agency for Healthcare Research and Quality suggest some leveling off of CDI in 2011, possibly because more sensitive diagnostics were introduced in 2010.

The CDC has taken note of the increasing CDI incidence. "It's on the top of our priority list," said Dr. McDonald. "Antibiotic stewardship is clearly something we need to do more of."

Dr. McDonald noted that England achieved about a 60% drop in CDI from a peak in 2008, largely by reducing prescriptions for fluoroquinolones and cephalosporins and increasing the use of broad- spectrum penicillins.

It remains to be seen whether a similar strategy can work in the United States. "We have a different healthcare system; it's fragmented and has independent practitioners," Dr. McDonald explained. "There are no reports that I am aware of that show any downsides to the British experience." It makes good epidemiologic sense, but it is not clear whether the hurdle of evidence-based medicine has been met, he noted.

Dr. Daniels and Dr. McDonald have disclosed no relevant financial relationships.

53rd Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract K-327. Presented September 10, 2013.

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