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Costs of Nosocomial Infections in the ICU and Impact of Programs to Reduce Risks and Costs

Durand-Zaleski, Isabelle MD, PhD*; Chaix, Carine MD*; Brun-Buisson, Christian MD

Clinical Pulmonary Medicine: January 2002 - Volume 9 - Issue 1 - p 33-38
Clinical Practice Management
Free

This study was undertaken to document the costs of nosocomial infections in the intensive care unit (ICU) and the impact of programs to reduce risks and costs of these infections. MEDLINE was searched from 1990 to 2000. The search strategy was: costs OR economics AND intensive care unit AND nosocomial infection ‘AND guidelines’ was added in a secondary search. The overall additional costs associated with hospital-acquired infections in the ICU varied from $3000 to $40,000 per patient and is associated with an additional length of stay of 5 days to roughly 3 weeks. The mean cost of antibiotics has been estimated from $1000 to $16,000. Implementing guidelines and screening and isolation programs reduced the rate of infection and the costs both of both antiinfectious agents and hospital days. The expected savings from reduction in the rate and severity of nosocomial infections offset the costs of implementing prevention programs.

*Department of Public Health and †Department of Intensive Care Medicine, Hôpital Henri Mondor, AP-HP, Paris, France.

Address correspondence to: Isabelle Durand-Zaleski, Santé publique, 51 avenue du Maréchal de Lattre de Tassigny, 94010 Créteil, France. Address e-mail to: isabelle.durand-zaleski@hmn.ap-hop-paris.fr

Economic aspects of nosocomial infections are a concern to patients, physicians, hospital administrators, and public health decision makers. We present in this short review the data available on the costs of nosocomial infections associated with admissions in the ICU and the impact of programs implemented in ICUs to reduce risks and costs of these infections.

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BACKGROUND

The total cost of nosocomial infections in developed countries has been estimated to be 1 billion US$ in Europe, 5 to 10 billion US$ in the United States (1,2), for a total estimated 2 million cases per year (3). The average incremental cost per infected patient has been estimated to vary between 1 and 2000 US$. The cost of prevention, according to the Centers for Disease Control, is $60,000 for a 250-bed hospital or roughly $250 million USA-wide (4). The costs of prevention, weighted by the effectiveness of the preventive measures taken, should be related to the cost of infections averted. It has been shown that a 6% absolute reduction in infection rate breaks even, i.e., the cost of prevention equals the costs of infections averted. These strictly economic computations do not take into account the other benefits of prevention, e.g., reduction in mortality and morbidity.

One particular aspect of prevention programs in hospitals is that they concern ‘statistical’ patients, in which the beneficiaries of the money expended to reduce the risks of infections will benefit patients who remain unknown. It is difficult to demonstrate to hospital managers that this money was correctly and efficiently used as long as the beneficiaries cannot be identified (5,6).

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METHODOLOGICAL ISSUES

The costs associated with nosocomial infections in the intensive care unit (ICU) have been documented in more than 40 studies published in peer-reviewed journals. The authors usually documented the costs associated with all nosocomial infections (surgical wound, urinary infections, pulmonary infections, catheter infection, bacteremia). Most studies concerned all microorganisms, however, some authors considered the costs associated with resistance to antimicrobial agents (methicillin-resistant Staphylococcus aureus [MRSA], Acinetobacter baumanii, vancomycin-resistant Enterococci). The context of the cost studies varied from medical, neonatal, and surgical ICUs.

This heterogeneity of setting, type of infection, and etiology explains the variability of the results. Moreover, this variability is increased by the use of different methods for cost computations. Some authors used charges or the hospital bill, whereas others used actual medical costs and sometimes estimated production costs. The correct method to estimate the costs associated with nosocomial infections is to compare the costs of treatment for infected patients to the costs of identical noninfected patients. Such comparisons require either case-control studies, or modeling (7). The biases that result from using different approaches to costing have been documented by Glynmark with the conclusion that very few costs studies provide correct cost data (8). This paper is cited here to caution readers that the cost data presented in this review may not be relevant to a different ICU setting and that improving the methodology of patient costing in the ICU is a worthy undertaking.

The costs of nosocomial infections in the ICU result from both prolonged length of stay and increased resource utilization per patient hospital day. This explains why a simple cost per day approach may not be accurate and it is therefore incorrect to estimate a total additional cost by multiplying the added length of stay by an average daily cost. It is equally incorrect to use reimbursement prices which bear little relation to actual costs (8).

Why is it interesting to document the cost of nosocomial infections in the ICU? The answer to this question is, in our view, twofold. One aspect is related to the budgetary process: ICU/hospital managers explain higher expenditures by a higher rate of infection. Another aspect stems from the ongoing debate on strategies for prevention and implementation of guidelines to screen, isolate, and limit antibiotic use. For example, there is persisting debate on the justification and costs versus benefits of implementing MRSA control programs in hospitals were MRSA is endemic (9–14). Three major objections to implementation of such control programs are commonly emphasized: 1) except for recent epidemics, their efficacy is poorly documented (10); 2) their costs are substantial, and suspected to obviate their potential benefits; and 3) infections caused by resistant bacteria do not appear to incur higher morbidity than those caused by susceptible strains. Cost studies could therefore be used to justify infection control programs (15–18). or implementation of practice guidelines that provide clinical pathways and restrict choice of initial empiric antibiotics (19,20). A number of hospital teams have tackled the issue of appropriate antibiotic use, and particularly the use of vancomycin. The rationale for these programs is exemplified by the case of the Paris hospitals (see Figure). Although the total number of MRSA strains decreased, prescription of vancomycin continued to increase.

Figure 1

Figure 1

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MATERIALS AND METHODS

We performed a literature survey with articles obtained through MEDLINE. The database was searched from 1990 to 2000, the date cutoff was chosen because the changes in practice patterns and availability of drugs and devices are likely to render moot any study older than 10 years. The search strategy was: costs OR economics AND intensive care unit AND nosocomial infection. A secondary search identified articles that dealt with guidelines to reduce nosocomial infections

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RESULTS

The overall additional costs associated with hospital-acquired infections in the ICU varied from $3000 to $40,000 per patient depending on the microorganisms involved, site of infection and comorbidities, this additional cost was associated with an additional length of stay of 5 days to roughly 3 weeks. The mean cost of antibiotics has been estimated from $1000 to $16,000. The actual total cost of nosocomial infection is usually underestimated because production costs (earnings foregone because of absence from work) and other costs such as those borne by the family are not included in computations (21).

Tables 1 to 4 (22–40) show the costs of different types of infections derived from several case-control studies, models, and multivariate analyses. Three recent articles provided information on the economic impact of the use of guidelines to reduce nosocomial infections. One study dealt with a neurologic ICU (NICU) (41), another with a surgical ICU (SCIU) (42), and the third one with the entire hospital population, including ICU beds (43). The guidelines concerned antibiotic use in the NICU, a variety of protocols for ventilator-dependent patients in the SICU, and a vancomycin-prescription control program in the latter case.

Table 1

Table 1

Table 2

Table 2

Table 3

Table 3

Table 4

Table 4

All three studies found that implementing guidelines reduced the rate of infection and the costs, although comparisons are difficult because of the use of heterogeneous indicators. In the two studies that focused on antibiotic use, the rate of infection by any microbial agent was significantly reduced and the antibiotic costs, measured in dollars per 1000 patients days were reduced by roughly 40% (41,43).

Preventing adverse events (not only infections) in ventilator-dependent patients reduced length of stay from 20 to 15 days and costs form $72,000 to $58,000 (42).

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DISCUSSION

In their analyses of the burden of nosocomial infections in the ICU, authors have usually considered two variables: length of stay (a proxy for costs) and costs. Data from a variety of medical, surgical, and neonatal ICUs indicate that the additional length of stay from nosocomial infections vary from 6 to over 20 days, the highest figures being often related to bloodstream infections and pulmonary infections, particularly those associated with invasive ventilation; these figures were usually obtained from case control studies. Not only are there serious methodologic issues in the computations used by the authors, but differences in hospital costs are to be expected. A recommendation should be that researchers agree on a common costing methodology to report cost data and not use average per diem costs multiplied by additional length of stay, since it has been shown that the cost per day is not the same over the duration of the ICU stay and not the same for infected and non infected patients (44).

Because of the important consequences on health, costs. and ecology, nosocomial infections must be the target of prevention programs. Most of these programs are easily cost beneficial because of the rather low costs of the prevention and isolation. Infection control programs and guidelines that have been assessed can be roughly separated in two groups. The first group is surveillance by daily cultures and preventive isolation of patients. The study by Zuckerman and coworkers (17) recommends daily cultures and contact precautions for infected patients. The study by Chaix and colleagues (16) recommends cultures and preventive isolation if the usual prevalence of infection in the ICU is above a threshold of 4% to 6%. Finally, Price and coworkers have developed guidelines (clinical pathways) for the diagnosis and management of intraabdominal infection, complicated skin, postoperative wound, skin struction infection, lower respiratory tract, urinary tract infection, sepsis, and IV catheter-related infection (19).The second group of guidelines concerns only the use of antiseptic-impregnated central venous catheters to reduce the risk of bloodstream infections (45,46). The cost per patient of infection-control programs is $40 to $80 per patient for cultures, supplies or antiseptic impregnated central venous catheters and $400 when all hospital costs are considered. However the decision-making process and the uncertainty about the results of screening and isolation programs often hampers their implementation (16–18,45,46).

Guideline implementation programs that require the intervention of an infectious disease consultant, a bacteriologist or a pharmacists would be more costly. It must be noted that studies of interventions to improve the appropriate use of antiinfectious agents or to reduce the use of vancomycin in the hospital have not estimated the cost of running the programs (41,43). The same can be said of the quality assurance program to reduce adverse events in ventilator-dependent patients. This program has required ‘daily collaborative bedside rounds, monthly meetings, and implementation of numerous guidelines and protocols’, none of which were costed (42). Although it is likely that reductions in inappropriate drug use and ICU length of stay will offset the additional cost of hiring consultants, data should be provided if intensivists are to convince hospital administrators and payors.

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Keywords:

Economics; Costs; ICU; Nosocomial infections; Guidelines

© 2002 Lippincott Williams & Wilkins, Inc.