Initial remarks: This blog, written by Lawrence F Muscarella, PhD, lists several factors that might cause:

  • the central line-associated bloodstream infection (CLABSI) rate to be under-reported;
  • the over-exaggeration of the effectiveness of an evaluated intervention, bundle of best practices, or checklist, based on estimated CLABSI rates; and/or
  • a reduced CLABSI rate to be misattributed to this intervention, bundles or checklist.

The comprehensive study upon which this blog is based, that discusses these several actors in detail, and describes the controversy surrounding the measurement of CLABSIs is entitled “Published Infection Rates: More Conjectural than Scientific?,” which can be read by clicking here.

1. Measurement bias, which may result from, among other factors, the employment of surveillance methods that lack the necessary sensitivity to measure, interpret, and report CLABSIs.10,11,46 Such methods might “miss,” or not count, a CLABSI due to, for example: a. not culturing the blood samples of patients suspected of a CLABSI for all types of recognized pathogens, including fungi and aerobic and anaerobic bacteria; b. mis-interpreting ambiguous definitions of CLABSIs;46 c. using too low a blood volume for culturing;11 and d. misclassifying primary bloodstream infections associated with central lines, namely, bona fide CLABSIs, as false positives (e.g., a common skin contaminant such as coagulase-negative staphylococci) or as secondary infections attributed to another site. 11,18,19,30,36,37

2. Financial bias, which may result from, for example, reimbursing or financially rewarding hospitals that report a reduced CLABSI rate (e.g., CMS’s pay-for reporting program);10,21,22,25-27 or from one or more potential financial conflicts of interest associated with a hospital reporting a reduced CLABSI rate.32,39

Click here to read a peer-reviewed article by Dr. Muscarella entitled “Assessment of the Reported Effectiveness of Five Different Quality-Improvement Initiatives for the Prevention of Central Line-Associated Bloodstream Infections in Intensive Care Units.” This detailed article complements this blog’s discussion of the effectiveness of federal efforts to reduce the rate of CLABSIs in ICUs.

3. Feedback bias, resulting from clinicians and staff members being, not blinded, but instead provided with “feedback” about a study’s intent and the success of their efforts to reduce CLABSI rates in ICUs.18-24,35,43,45

4. Publication bias, resulting from, for example, the tendency to report only favorable CLABSI data; or, to report or publish incomplete data.19,22,35,36,38,45

Click here to read a related blog by Dr. Muscarella “Dear Pediatrics: An Assessment of the Effectiveness of Bundles and Checklists.”

5. Sampling bias, resulting from ICUs treating diverse patient populations that have not been randomized or adjusted for different risks of CLABSI (e.g., high-risk populations, varying birth weights in neonatal ICUs).45

Studies that describe quality improvement initiatives, but that whose prospective designs are not controlled, cannot display causal relationships, only associations between an intervention’s implementation and its effect on the infection rate. — Lawrence F Muscarella PhD

6. Confounding bias, resulting from such factors as:

  • administration of antimicrobial therapy without having first obtained a blood culture to confirm a CLABSI (such therapy should be started, when possible, after a blood culture has confirmed infection);41
  • use of different medical supplies, such as catheter dressings or insertion-site antiseptics, or the use of catheters impregnated with antimicrobial agents; and
  • other changes in infection-control techniques or behaviors,20 including:
    • changes in the catheter’s use;45
    • use of more experienced physicians to insert and maintain central lines (as opposed to less skilled residents); or
    • changing catheter dressings more often.

Again, this blog is incomplete and does not include tables and box articles that are important to its understanding. Check here to read this article in its entirety.

References to this blog: Click here.

Blog by: Lawrence F Muscarella PhD posted on 12-13-2012

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