425. Does Electronic Clostridium difficile-Associated Disease (CDAD) Surveillance Underestimate Disease Burden?
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: Increasing incidence and severity of CDAD are of concern. CDAD surveillance typically relies on positive stool toxin assays. Because CDAD is often treated empirically and toxin assays may not always be obtained, current surveillance may underestimate CDAD incidence. We sought to define the degree of underestimation of CDAD and examine surrogate definitions.
Methods: Monthly inpatient Clostridium difficile toxin assay orders and results, oral/intravenous metronidazole, or oral vancomycin usage were obtained from a CCH electronic database. Toxin orders were available from 8/07-12/08; other data elements were available from 8/01-12/08. Pairwise Pearson correlation coefficients (r) between toxin assay rates, antibiotic therapy, and toxin assay orders and linear regression for relationships between factors and toxin positivity were calculated.
Results: Positive correlation was found between positive toxin assay rate and 1) anti-CDAD therapy (r=0.30, p=0.006) and 2) assay ordering (r=0.748, p = 0.001). Regression found that for each toxin-positive CDAD case /1000 inpatient-days (ptd), 14 additional untested patients/1000 ptd received anti-CDAD antibiotics (Figure). On average, 27.6% of orders for CDAD toxin tests were never fulfilled.
Conclusion: A significant proportion of suspected CDAD is likely never diagnosed: 30% of orders for toxin assays are not completed, and only 7% of patients receiving anti-CDAD antibiotics have toxins obtained. Toxin results may provide useful data regarding CDAD trends but may underestimate total disease, and surrogates may enhance estimation of true CDAD incidence.
J Como, MD1, Bala Hota, MD2, I Oana, MD1, K Popovich, MD3, R Weinstein, MD4 and  J. D. Como, None..
I. Oana, None..
K. J. Popovich, None. 
B. Hota,
Pfizer Speaker's Bureau Role(s): Speaker's Bureau, Received: Other Financial Benefit.
R. A. Weinstein, None., (1)Cook County Hosp. (CCH), Chicago, IL, (2)John H. Stroger, Jr. Cook County Hospital, Chicago, IL, (3)Rush Univ, Chicago, IL, (4)Rush Medical College