Healthcare-associated infection and antimicrobial resistance: moving beyond description to prevention.

Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, and George W. Merck Fellow, the Institute for Healthcare Improvement, Cambridge, Massachusetts (B.L.Z.); and the Institute for Healthcare Improvement, Cambridge, Massachusetts (D.A.G.) Received February 12, 2007; accepted February 12, 2007; electronically published February 20, 2007. Infect Control Hosp Epidemiol 2007; 28:261-264 2007 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2007/2803-0002$15.00. DOI: 10.1086/513722 The burden of healthcare-associated infection (HAI) and infections caused by healthcare-associated multidrug-resistant organisms (HA-MDROs) is substantial. The Centers for Disease Control and Prevention (CDC) estimates the annual number of HAIs in US hospitals at about 1.7 million, resulting in approximately 99,000 deaths, which makes HAI the most common infectious cause of death and one of the 10 leading causes of death overall. Included in these troubling statistics are at least 350,000 infections and 12,000 deaths caused by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci, and Clostridium difficile. It is estimated that infections caused by these multidrug-resistant pathogens result in at least $3.5 billion in excess healthcare costs annually (CDC, unpublished data). Three articles in this issue of the journal seek to shed additional light on estimates of the mortality, excess length of stay, and costs attributable to HAI. The first of these, a study from France by Fabbro-Perray et al. measured the attributable mortality of HAI using a large, prospective, matched-cohort study design in a single hospital. The researchers determined that the population-attributable risk of HAI-attributable mortality throughout France lies between 2.1% and 4.0%, on the basis of a 3%-6% range in the incidence of HAI in French hospitals. The second study, by Shurland et al., reports on a 9-year retrospective cohort study of S. aureus infection complicated by bacteremia in a single Veterans Health Administration system, found that patients with MRSA infection, excepting those with pneumonia, had higher mortality than did patients infected with methicillinsusceptible S. aureus. Together these 2 reports emphasize that HAI and HA-MDROs are associated with increased mortality independent of the patient’s underlying illness. The third article, by Graves et al., is a prospective cohort study performed in 2 Australian hospitals that examined excess costs and length of stay attributable to HAI. The authors conclude that HAIs (urinary tract infections, lower respiratory-tract infections, and “other” infections) are associated with little excess cost or length of stay. Specifically, they found only US$17 of extra variable costs and 2.58 extra hospital days per case of lower respiratory-tract infection, whereas urinary tract infection resulted in no excess costs or length of stay, and “other” infection resulted in no excess costs and only 2.61 extra hospital days. The findings of Graves et al. stand in marked contrast to previous higher estimates based on either a matched-cohort approach or the regression analysis methods favored by Fabbro-Perray et al. and Shurland et al. These 3 studies complement a vast and growing literature on the clinical and financial impact of HAI and HA-MDROs. Investigators have studied diverse populations and used a variety of epidemiological and statistical approaches to control for bias and confounding. Not surprisingly, the range of attributable harm and cost varies dramatically. For example, the cost per case of MRSA infection ranges from $7,000 to $32,000 in published studies. In general, but not always, the more aggressive the statistical approach to confounding, the lower the attributable risk. Of course, no amount of statistical manipulation can compensate fully for unmeasured factors, although the use of instrumental variables is a promising partial solution to this problem. At this point in the long history of infection control, it is reasonable to ask why we need more descriptive epidemiological studies of the attributable risk of HAI. Estimating the mortality, excess length of stay, and costs attributable to HAIs would be an interesting academic exercise were there not increasing evidence that most, if not all, of these infections are preventable. Although there are numerous examples of successful smallscale interventions to eliminate adverse events, including HAIs, in hospitals, the rate of overall improvement has been slow. The public is frustrated, and consumer groups are promoting legislation mandating public reporting of rates of infection and other healthcare-associated adverse events. Impatient with the pace of quality improvement nationally, in December 2004 the Institute for Healthcare Improvement (IHI) launched the 100,000 Lives Campaign, a national initiative to prevent 100,000 unnecessary inpatient deaths within 18 months. To help reach this goal, the Campaign proposed