A joint post with Nikolay Braykov.
A CDC Vital Signs report has taken on the changing epidemiology of Clostridium difficile infections, showing a dramatic increase in prevalence and mortality associated with the disease in the past decade. Most at risk for developing the serious gastrointestinal infection are patients taking antibiotics who also receive care at any kind of medical facility.
Unlike the recent gains in combating other healthcare-associated infections, including central-line associated blood stream infections (CLABSIs) and hospital-associated MRSA, the trajectory of C. difficile infections is cause for concern. According to the Vital Signs report, hospitalizations for C. difficile infections increased nearly three-fold over the past decade, and mortality rose 400% between 2000 and 2007. In part, this increase is due to the emergence of a more virulent C. difficile strain.
Antibiotic use puts a patient at higher risk for developing a C. difficile infection, because antibiotics can wipe out the good bacteria in the gut, allowing C. difficile to thrive. Paradoxically, certain antibiotics also treat C. difficile. We used the ResistanceMap platform to take a look at how rising mortality associated with C. difficile is correlated with one of these antibiotic treatments oral vancomycin. The following interactive map shows the population-adjusted state mortality from C. difficile, and the animated bubble plot relates deaths with outpatient prescribing rates of oral vancomycin.
The visualization both confirms what we know and leads to some new questions about geographical spread.
First, between 2000 and 2007 there is a striking increase in C. difficile mortality, from 0.42 to 2.15 deaths per 100,000 population. Hospitalization data shows that not only are more people developing infections, but cases are more likely to be fatal as C. difficile strains become increasingly virulent and drug-resistant.
Second, looking across regions, the burden of C. difficile infections is notably higher in the Northeast (Maine, Rhode Island). Other studies document the clustering of C. difficile and inflammatory bowel diseases in those states, highlighting the need for further research into environmental factors that drive the pattern.
Third, there is strong temporal and geographic correlation between vancomycin prescribing and C. difficile mortality. Here is a static bar graph showing only the relationship between C. difficile-associated mortality and oral vancomycin prescribing (unfortunately our antibiotic prescribing data stops in 2007).
As previously noted in this ICHE paper, this correlation makes 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.
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