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Public Health Focus: Surveillance, Prevention, and Control of Nosocomial Infections
Nosocomial infections are estimated to involve more than 2 million patients annually (1,2) and in 1992 cost more than $4.5 billion (3). Adverse consequences of nosocomial infections and their associated costs vary by type of infection (Table 1) (3). Hospital-based programs of surveillance, prevention, and control of nosocomial infections were developed during the 1950s and refined in the United States during the 1960s and 1970s. However, questions regarding the efficacy and cost-effectiveness of these programs have persisted. This report examines knowledge about the effectiveness of nosocomial infection surveillance, prevention, and control and their cost-benefits. Efficacy/Effectiveness
During the 1960s, U.S. hospitals organized infection-control programs to conduct surveillance, develop control measures, and develop and implement infection-control policies. In 1976, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) added to its standards for accreditation the presence of an infection surveillance and control program in accredited hospitals.
In the early 1970s, CDC initiated the Study on the Efficacy of Nosocomial Infection Control Project (SENIC) to examine the effectiveness of nosocomial infection surveillance and control programs in the United States (2). Objectives of SENIC were to 1) measure the extent to which newly developing infection-control programs had been adopted in U.S. hospitals and 2) determine whether and to what extent these program had reduced nosocomial infection rates. SENIC methodology included a survey in 1976 of all U.S. hospitals to determine specific surveillance and control characteristics of their infection-control programs and, in 1975- 1976, review of more than 339,000 patient medical records in 338 randomly selected U.S. hospitals to determine the presence of nosocomial infections (4).
SENIC found that hospitals reduced their nosocomial infection rates by approximately 32% if their infection surveillance and control program included four components: 1) appropriate emphases on surveillance activities and vigorous control efforts, 2) at least one full-time infection-control practitioner per 250 beds, 3) a trained hospital epidemiologist, and 4) for surgical wound infections (SWIs), feedback of wound infection rates to practicing surgeons (2). However, the components needed for prevention varied for the four major types of nosocomial infection (i.e., SWI, urinary tract infection, bloodstream infection, and lower respiratory tract infection) (Table 2) (5,6).
As the only controlled study of the effectiveness of infection surveillance and control programs, SENIC provided the basis for an infection-control strategy employing epidemiology (7). However, in the mid-1970s, only 0.2% of U.S. hospitals had programs that were effective in reducing all four major types of infections. Although approximately one third of nosocomial infections in the U.S. hospitals could have been prevented, in 1976 approximately 6% of all such infections were actually being prevented (8). In 1983, another survey of infection surveillance and control programs in a random sample of U.S. hospitals found that hospitals had substantially increased the intensity of their surveillance and control activities. However, the failure to implement certain critical components (e.g., an adequate staffing ratio for infection-control practitioners, a trained physician epidemiologist, or reports of wound infection rates to surgeons) had limited the maximum potential for improvement in prevention (at that time, such programs were capable of preventing an estimated 9% of infections) (9). Cost-Effectiveness and Cost-Benefit
The publication of the findings of SENIC established the effectiveness of infection-control programs. However, other concerns regarding the cost-effectiveness and cost-benefit of such programs have emerged as the methods of reimbursement for U.S. hospitals have changed (10).
Complete cost-benefit analyses provide estimates of all costs of nosocomial infection that are saved by effective programs, including physicians' fees and costs to the patient for time off work. In addition, computation of these costs should include salary and overhead of the infection-control staff and the cost of patient-care practices (e.g., handwashing costs) to prevent cross-infection.
Based on these considerations, the cost of an infection-control program (in 1985 dollars) has been estimated to be $60,000 per 250 beds, projecting to all U.S. hospitals a cost of $243 million (6). To estimate the potential benefits from prevention nationwide, the costs of nosocomial infections (in 1985 dollars) were estimated to be approximately $4 billion. Using these estimates, the costs of having an infection-control program would equal the amount saved by preventing hospital infections when approximately 6% of the infections are prevented (6,11). If the percentage of the infections prevented were greater than 6%, then a net savings to the hospital would occur. Under the prospective payment system, virtually the entire cost of nosocomial infections represents an operating deficit. Effective infection surveillance and control programs are the only way to reduce that cost (6).
Even though methodologies to measure cost-benefit of infection surveillance and control programs have varied, all available studies have shown a benefit to the hospitals (6).
Reported by: Hospital Infections Program, National Center for Infectious Diseases, CDC.
Editorial Note: Prevention of nosocomial infections remains a major objective of U.S. hospitals and of other health-care and professional organizations such as JCAHO, the American Hospital Association (AHA), the Association for Practitioners in Infection Control, the Society for Hospital Epidemiology of America (SHEA), the Surgical Infection Society, and the Public Health Service (12,13). Despite some of its limitations, findings from SENIC have enhanced the practice of infection control in the United States by providing a scientific basis for determining the effectiveness of infection surveillance and control programs; this basis may be unique among programs addressing complications of hospitalization.
The findings of SENIC have also suggested the need for physician training in infection control. As a result, SHEA, AHA, and CDC have provided a training course in hospital epidemiology for physicians.* In addition, the results of SENIC affirmed interest in surveillance of nosocomial infections and demonstrated the importance of using selected outcome measures (e.g., nosocomial infection rates) from targeted surveillance.
To better meet the need for outcome measures from targeted surveillance, CDC's National Nosocomial Infection Surveillance (NNIS) System -- the only source of national data on the epidemiology of nosocomial infections in the United States -- revised its methodology in 1986 (14-16). The use of risk-adjusted infection rates and feedback of the distributions of these rates to the NNIS hospitals have helped refine outcome measures that will provide more meaningful rates for interhospital comparison (14). The Institute of Medicine recently recommended expanding the role of the NNIS system in refining outcome measures (17). JCAHO has adapted the NNIS methods and is beginning to collect information on a wide range of clinical indicators in infection control; seven of these indicators are outcome measures (13). During the 1990s, infection surveillance and control programs will continue to evolve and, with progressive computerization in hospitals, these programs will emphasize the role of outcome measurement for quality improvement and disease prevention.
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