Epidemiology of Clostridium difficile infection in a large population of hospitalized US military veterans.

The Patient Treatment File (PTF) of the Department of Veterans Affairs (VA) comprises the computerized records of all inpatients treated at all VA hospitals throughout the United States. The database was utilized to study the clinical epidemiology and impact of C. difficile colitis on health care among hospitalized US military veterans. The computerized medical records of 15,091 cases with C. difficile colitis and 61,931 controls without the diagnosis were extracted from the annual files between 1993 and 1998. Of all patients admitted to the hospital, 1% were diagnosed with C. difficile colitis, in 16% of whom it was listed as the primary discharge diagnosis. C. difficile colitis was more likely to occur in elderly white patients with multiple comorbid conditions. Compared with a control population of hospitalized patients without C. difficile colitis, the case population was subjected to more medical and surgical procedures and experienced longer hospital stays. The diagnosis of C. difficile colitis was associated with more frequent admissions to the intensive care unit and higher hospital-related and subsequent mortality. Eleven percent of the cases were admitted to hospital a second time after a mean of 202 days, 2.5% were readmitted a third time after an additional 182 days, and 0.8% were readmitted a fourth time after an additional 194 days. In conclusion, as old age, multiple comorbid conditions, a high number of medical and surgical intervention, and long hospitalization constitute the main risk factors for the development of C. difficile colitis, efforts at prevention should be directed primarily towards patients who present with these characteristics.