When Counting Central Line Infections Counts

Abstract

Affiliations: 1. Department of Health Sciences, University of Leicester, Leicester, United Kingdom; 2. Center for Comprehensive Access and Delivery Research and Evaluation, Iowa City Veterans Affairs Health Care System, Iowa City, Iowa; and Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa. Received February 28, 2013; accepted March 3, 2013; electronically published April 18, 2013. 2013 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2013/3406-0002$15.00. DOI: 10.1086/670630 In this issue of the journal, Wise et al report encouraging news of significant declines in reported rates of central venous catheter (CVC) bloodstream infections (BSIs) in critical care units over the past 2 decades. Using data from the US Centers for Disease Control and Prevention’s (CDC’s) National Nosocomial Infections Surveillance system for the years 1990– 2004 and the National Healthcare Safety Network (NHSN) for the years 2006–2010, the authors carefully adjusted for changes in definitions, changes in hospital facility characteristics, and potential bias arising from the transition to the NHSN. They estimated that between 100,000 and 200,000 fewer infections have occurred compared with what might have been expected if infection rates had remained stable at 1990 levels. Much of the improvement can be attributed to increased utilization of evidence-based procedures for line insertion, along with such technical innovations as antimicrobial catheters and chlorhexidine insertion-site patches. More broadly, these declines are likely due to sweeping cultural change. The 2006 Michigan Keystone project in particular may be said to have disrupted the prevailing norm that hospital-acquired infections (HAIs) were simply the price of doing business in critical care. With its report of a reduction from a mean 7.7 to 1.4 central line BSIs per 1,000 catheter-days in more than 100 intensive care units (ICUs), the Keystone project demonstrated that many—though not all—central line infections are preventable. The findings of Wise and colleagues will be welcomed by patients, practitioners, and payers. But there is some room for caution, on 3 counts. The first relates to the appropriation of definitions intended for surveillance for purposes for which they were not originally designed. The second is linked and relates to the elasticity of notions of preventability. The third is that we may be reaching the limit of preventability, and we may have to confront the possibility that zero infections may not be an achievable goal in all circumstances. A small but important body of work points to considerable variability in how definitions of central line infections are applied and interpreted. One study, using 2004–2007 data from 20 ICUs at 4 large academic medical centers, found limited correlation between CVC BSI rates determined by infection preventionists and a computer algorithm–generated standard rate. A retrospective survey in 6 Australian hospitals found “unacceptably low” agreement between reported CVC BSIs and gold standard application of definitions. A recent ethnographic study of English ICUs points to some of the reasons why variability occurs in what gets counted as a CVC BSI: mundane challenges (setting up and operating data collection systems), clinical practices in dispatching samples for microbiological analysis, and differences in clinical judgement all play a part. Much of the variability has its roots in the CDC definitions themselves, which were designed for surveillance. Maximizing sensitivity—the detection rate—has traditionally been a goal of surveillance systems for HAIs because ensuring that all candidate infections are identified and that appropriate action is taken likely serves the best interests of patients. High specificity—indicating a low false-positive rate—is clearly a benefit too, mainly to avoid overtreatment and unwarranted costs. The CDC catheter-associated (not catheter-related) definition, used by many US hospitals, is known to maximize sensitivity and thus may overcount CVC BSIs. But recent policy developments, by appropriating HAI surveillance rates as a form of performance management, are changing the rules of the game. In October 2008, the US Centers for Medicare and Medicaid Services (CMS) eliminated additional payments for certain hospital-acquired conditions, including CVC BSI, and since January 2011 the CMS has required all hospitals participating in the Inpatient Prospective Payment System to report CVC BSI rates using the CDC’s NHSN. Currently, 32 states and the District of Columbia have policies requiring the reporting of CVC BSIs. Public report cards and rankings compiled by the media and advocacy groups now draw on