DENVER – The incidence of Clostridium difficile infections in United States hospitals nearly doubled between 2001 and 2010, with little evidence of recent decline. In addition, there does not appear to be a significant decline in mortality or hospital length of stay among patients with the infection, an analysis of national data showed.
"These data underscore the importance of directing resources to the prevention of [C. difficile infection], as well as developing public policy for reducing the incidence of these infections in U.S. hospitals," Kelly R. Daniels, Pharm.D., said in an interview prior to the annual Interscience Conference on Antimicrobial Agents and Chemotherapy, where the study was presented.
Dr. Kelly Daniels
"Judicious use of antibiotics is essential to reducing these infections, as antibiotics are the main risk factor for the development of CDI," she noted. "Compliance with other infection control measures, such as hand washing, is also key. Further research is needed to identify effective measures for preventing CDI and improving outcomes in patients with CDI."
Dr. Daniels, a graduate student in the translational science PhD program at the University of Texas, Austin, and her associates retrospectively reviewed U.S. National Hospital Discharge Surveys from 2001 to 2010. They included patients aged 18 years and older who were discharged from the hospital with an ICD-9-CM diagnosis code for CDI (008.45) and used data weights to determine national estimates. They presented incidence rates as CDI cases per 1,000 hospitalizations, and they used multivariable logistic and linear regression models to compare mortality and hospital length of stay between primary and secondary CDI.
Over the 10-year study period, 2.2 million patients were discharged from the hospital with CDI. Their median age was 75 years, most (86%) were white, and more than half (59%) were female. One-third of cases (33%) were primary CDI, while the remainder were secondary CDI. The three most common concomitant infectious diagnoses were urinary tract infection (21%), pneumonia (14%), and sepsis/septicemia (12%).
Dr. Daniels reported that the incidence of CDI increased from 4.5 cases/1,000 hospitalizations in 2001 to 8.2 cases/1,000 hospitalizations in 2010. Similar trends were observed in patients with primary and secondary CDI.
The overall mortality rate was 7.1% for the study period and was significantly higher among patients with secondary CDI, compared with those who had primary CDI (8.8% vs. 3.3%, respectively; relative risk, 1.8). The median hospital length of stay was 8 days and was significantly higher among patients with secondary CDI, compared with those who had primary CDI (9 days vs. 5 days, respectively; RR, 13.3).
"We found that in-hospital mortality among patients with primary CDI is decreasing, while mortality among patients with secondary CDI is increasing," Dr. Daniels said. "This trend is different from prior studies, which demonstrated increases in CDI-related mortality from the 1990s to the early 2000s."
The decline in in-hospital mortality among patients with primary CDI might reflect improvements in care in recent years, she explained. In contrast, the increase in mortality among those with secondary CDI may be caused by changes in the frequency or severity of other comorbid illnesses. However, "this was not specifically examined as part of our study," Dr. Daniels added.
She acknowledged certain limitations of the analysis, including the fact that it relied on administrative codes to identify cases of CDI. "Although CDI codes have high accuracy for identifying CDI, they cannot be considered equivalent to medical chart reviews," Dr. Daniels explained. Also, "the use of administrative codes precludes our ability to confirm the CDI diagnosis using laboratory methods or to identify the causative strain of C. difficile." In addition, the National Hospital Discharge Surveys don’t include federal hospitals and long-term care hospitals. "Therefore, our estimates may not be generalizable to those settings and may underestimate the true burden of CDI in the United States," Dr. Daniels explained.
No outside funding was obtained for the conduct of this study. Dr. Daniels disclosed that she is supported by the National Institutes of Health National Center for Advancing Translational Sciences Loan Repayment Program.