Surveillance practice variation is of two types, the way cases are found and the way they are classified, the authors wrote. First, case findings of potential bloodstream infections may be incomplete, in that a patient may have multiple positive blood cultures throughout a prolonged intensive care unit stay, "not all blood cultures may be investigated, especially if the infection preventionist does not have a systematic method of tracking blood culture results."
In the second type, classification, there is substantial variation in application of subjective aspects in the central line-associated BSI definition. "For example, infection preventionists (and clinicians) will not always agree whether a positive blood culture originated from a central line or from an extravascular source such as an intra-abdominal abscess as a secondary BSI."
Where definitive information is not available, "infection preventionists may differently classify ambiguous cases."
Further confounding standardization, there also may be qualitative differences at each institution, "such as local culturing practice, quality of medical documentation and strength of institutional oversight over infection prevention activities."
Most of the variability they found, however, "is explained by differences in infection preventionist performance of surveillance."
The researchers' conclusions are similar to those of Matthew Niedner, MD, and others who looked at 20 pediatric intensive care units earlier this year.