C. diff deadlier and more common than previously thought. How can prescribing data help tell the story?

21 Aug 2012

A cover story by USA Today last week focused on the growing burden of Clostridium difficile infections (C. diff) – a serious and potentially deadly gastrointestinal inflammation that is associated with antibiotic use in hospitals and nursing homes. According to the piece, nearly 30,000 people died from the infection in 2010, over twice the 14,000 estimated by the CDC Vital Signs report released this March. C. diff is emerging as a major challenge for the public health community: even though rates of other HAIs are on the decline, C. difficile infections are rising fast and are becoming deadlier due to the emergence of a more virulent strain.

In discussing solutions, the USA Today story stresses key ideas advanced by Extending the Cure: the need to strengthen hospital infection control, promote antibiotic stewardship in nursing homes and hospitals, and “[get] all the players to work together — from health care administrators and the government regulators.” However, although it acknowledges that C. diff “thrives in settings where antibiotics are in wide use,” the story discusses these infections exclusively as a hospital problem, omitting the importance of judicious antibiotic use in the community. In fact, the earlier CDC analysis shows 48% of cases start in the outpatient setting, and more than half of those lack prior hospital exposure.

Antibiotic prescribing– ­both in the hospital and in the community­– is an important piece of the C. diff puzzle and may present a novel way for tracking the epidemic. In addition to promoting the rise of more resistant strains, antibiotic use puts a patient at higher risk for developing C. diff in the first place, as antibiotics can wipe out the good bacteria in the gut and allow C. difficile to take over. Paradoxically, an antibiotic has to be used to treat that infection. 

Back in March, our Visualization Series looked at how rising mortality associated with C. difficile is correlated with one of two available antibiotic treatments – oral vancomycin (Vancocin). In light of the renewed media interest in the topic, we have updated the visualizations in our tools section to cover the 2000-2010 period and reflect the data from the USA Today story. The bar graph below shows the relationship between C. difficile-associated mortality, hospitalizations, and oral vancomycin prescribing at the national level.

The visualization furthers what we previously found: oral vancomycin use and mortality closely follow the upswing in hospitalizations, with the exception of 2002-2003 when there was a production shortage. The association holds at the subnational level: an updated interactive map available here shows the strong temporal and correlation between population-adjusted vancomycin use at the state level and state mortality from C. difficile. It also shows that the highest mortality burden is concentrated in the Northeast (Rhode Island and Connecticut heading the list), and lowest in the Southeast, raising questions about the geographic spread of C. diff strains. Unfortunately, hospitalization data was not available at the state level.

As previously noted in this ICHE paper, both geographic and spatial correlations make a strong case for the use of drug utilization data as a cost-effective form of disease surveillance for C. difficile.  Watching rates of oral vancomycin prescribing in the coming years should be able to tell us if we are making progress in curtailing C. difficile infections.

Further reading:

 

Thumbnail image via Wikimedia

Antibiotic Resistance