Wide Variety in C. difficile Underdiagnosis Seen Across Europe

By Anne Harding

November 26, 2014

NEW YORK (Reuters Health) - Tens of thousands of European hospital patients who are infected with Clostridium difficile go undiagnosed annually, according to a new study.

Among 482 hospitals in 20 countries, most hospitals were not using recommended methods to test for C. difficile infection, researchers reported in Lancet Infectious Diseases, online November 7. Rates of underdiagnosis also varied sharply from country to country, from 0% in Belgium, Ireland, the Netherlands, Slovenia and Sweden to over 60% in Bulgaria, Greece and Romania.

Astellas Pharma Europe (Chertsey, UK), which is developing and commercializing the C. difficile treatment Dificid in Europe, launched and funded the new study.

One main reason for underdiagnosis is the lack of a standardized system to test for the bacterium, Dr. Mark H. Wilcox of the University of Leeds in the UK, one of the coordinators of the new study, told Reuters Health.

"In many countries and many health care systems, if the doctor doesn't request the C. diff test to be done, then the test doesn't get done at all," said Dr. Wilcox, who has received grants and personal fees from multiple drug companies, including Astellas.

Identifying C. difficile infection is important, he added, both for treating patients and controlling the spread of infection. "Not only can we miss cases if you don't use the right test, but you can actually overdiagnose cases as well if you don't use the right test."

Dr. Wilcox participated in a major overhaul of the UK's C. difficile testing system, which required hospitals to randomly report C. difficile infection rates and also established standard methods for testing. All diarrheal fecal samples from hospital patients are checked for the disease, which involves screening for C. difficile and then conducting a toxin assay if the screen identifies the organism.

Previous research had shown a wide variation in the incidence of C. difficile infection and in testing frequency across European countries. In the current study, Dr. Wilcox and his team surveyed hospitals about their methods and testing policy for C. difficile infection during September 2011 to August 2012, and from September 2012 to August 2013. On a single winter day and a single summer day, each hospital also sent all diarrheal samples submitted to their laboratories to a national laboratory for standardized C. difficile testing.

On average, there were 65.8 tests performed for C. difficile infection per 10,000 patient-bed days, although this rate ranged from 4.6 to 223.3 per 10,000. There were seven cases, on average, per 10,000 patient bed days, with a range of 0.7 to 28.7 per 10,000.

A total of 7,297 samples were sent to the hospital, two-thirds of which had been tested for C. difficile at the hospital. A total of 641 samples tested positive at the national coordinating laboratories, 148 (23%) of which had not been tested for C. difficile at the hospital lab.

Five percent of the samples were false positives, meaning the hospital diagnosed the patient with C. difficile infection but the national lab did not identify toxigenic C. difficile in the patient's stool sample. Two percent were false negatives.

"Overall, 57% of patients tested for C. difficile infection across Europe during the EUCLID study had a diagnosis at their original participating hospital that agreed with the standard reference method as done at national coordinating laboratories," Dr. Wilcox and his team write.

The median age for patients who were found to have C. difficile infection by the national coordinating laboratory, but were not diagnosed at the hospital, was 65.5 years, versus 76 years for patients who were identified as having the infection at the hospital where they received treatment.

Dr. Wilcox is part of the team working on guidelines for C. difficile testing for the Infectious Disease Society of America. While it's likely many cases are underdiagnosed in the U.S. as well, he said, "I'm hopeful that when those guidelines are finished and published, which we're hoping will be next year, then that can go some way toward bringing better standards of testing."

Information is needed on outcomes for patients with C. difficile in the new study who were not diagnosed, Dr. Simon D. Goldenberg of King's College, London, wrote in an editorial accompanying the study.

"Were they tested again at a later date, empirically treated for C. difficile infection, or did they come to harm as a result of misdiagnosis?" Dr. Goldenberg writes. "These answers are central to understanding the clinical syndrome of underdiagnosis."

He added, "The success in reducing C. difficile infection that the National Health Service in England has experienced is evidence that improved awareness and enhanced mandatory surveillance has an important part to play. However, the foundation of good surveillance is optimum laboratory testing methods and sample selection policies. Although evidence suggests improvement in these areas across Europe, much more is still to be done. Davies and colleagues' findings justify a continued intense focus on strategies to reduce cases of C difficile infection."

SOURCE: http://bit.ly/1pj9xBZ and http://bit.ly/1zUOcjb

Lancet Infect Dis 2014.

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