	The Pan American Health Organization Promoting Health in the Americas

Health Surveillance and Disease Management / Communicable Diseases / Antimicrobial Resistance

Protocol for Calculating the Cost of Hospital Infections (Washington, DC, 2000)

Full Text (21 pp, PDF, 248 Kb) - Introduction - Some Observations on the Studies of the Cost of Hospital Infections (text to right) - Protocol - Objectives (text to right) - Characteristics - Ethical Considerations - Publication - Design Characteristics - Cost Indicators - Considerations for the Selection of Cost Indicators - Selection Criteria for Hospitals - Selection of Cases - Selection of Controls - Method for Selecting Controls - Considerations for Selecting Controls - Analysis - Collection of information on nosocomial bloodstream infections (BSIs) associated with oxacillin-resistant Staphylococcus aureus - Table 1: Data Collection Form for a Study on the Cost of Hospital Infections (See instructions for completing the form) - Instructions for Completing Table 1, Data Collection Form - List of Types of Infection - Table 2: Summary to Evaluate the Use of Antimicrobial Drugs by Type of Infection - Table 3: Summary, by Infection Site - Table 4: Summary for Each Hospital Infection Studied - Table 5: Summary of Excess Cost of Selected Hospital Infections - Table 6: Quality of Pairing or Matching by Infection Site - Table 7: Nosocomial Bloodstream Infections with Staphylococcus aureus, Sensitivity, and Oxacillin Resistance, and Total Number of Hospital Discharges - Table 8: Calculation Cost of a Bed/Day () - Acknowledgments PAHO Antimicrobial Resistance Page* - WHO Drug Resistance Page - WHO Pharamaceutical Products Page		Objectives Determine the excess cost attributable to hospital infections in selected hospitals. Train staff at the selected hospitals in methodologies for calculating the cost of hospital infections. Determine the cumulative incidence of bacteremias associated with Staphylococcus aureus and the proportion of such infections with resistance to oxacillin. Some Observations on the Studies of the Cost of Hospital Infections Determining the cost of hospital (or nosocomial) infections is a complex process and depends on the objectives established for the study. As a rule, the average cost of a case is determined; that figure is then multiplied by the total number of cases in the institution or country. Thus, the average cost of a case of hospital infection and the total number of cases of hospital infection must be known. These data can be obtained for total hospital infections or can be disaggregated by each type of hospital infection. Two broad types of designs have been proposed to determine the average cost of a case. In one, a certain cost is assigned on the basis of expert opinions; in the second, the cost is calculated by comparing different groups of patients, usually those with infections and those without them. The ultimate objective is to calculate the excess cost attributable to the hospital infection-that is, how much of the cost of caring for a patient with this type of infection can be attributed to the hospital infection per se. Studies that estimate the cost consist of analyzing cases of hospital infection and all the care and resources expended in the treatment of each patient and then deciding how much in each category of care (days hospitalized, antimicrobial drugs, other supplies) was utilized as a result of the hospital infection. These studies are easy to do but are not good for comparison purposes, since different groups of experts obtain different results for the same hospital infections. Furthermore, when analyzed in conjunction with comparative studies, it has been observed that the studies estimating the cost underestimate the actual cost of care. These should be considered the worse type of study for calculating costs and should only be used in the case of very rare infections. Comparative studies, in contrast, consist of determining the cost of the resources used for patients with hospital infections and comparing it with the cost for other groups of patients. For this comparison, three groups of patients are used: *All patients (with and without hospital infections)* in the service in which the hospital infection cases used in the study are found. Here, the data are relatively easy to obtain, but the cost of the hospital infections is underestimated because infected patients are included in the comparison group. *Patients without hospital infections, for whom the data are fairly easy to obtain. However, in this group the cost of hospital infections is overestimated, since, as a rule, patients who develop infections are patients with more serious illnesses, who have other problems that drive up the cost of hospital care. Patients with hospital infections (cases), coupled with patients without hospital infections (controls), by age, sex, and some indicator of the severity of the disease in each case. Here, the data are fairly difficult to obtain, since the matching process is laborious, although computerized systems with the patients' clinical histories are available. These studies yield the most accurate results and are considered the gold standard. However, they depend on the quality of the local records for certain variables. In addition, it is sometimes difficult to find the match for a complex case (for example, a 70-year old diabetic with pneumonia associated with mechanical ventilation, hospitalized in the ICU for necrohemorrhagic pancreatitis). For this reason, this type of study has generally been limited to the most common hospital infections. Infections in catastrophic cases, such as the one in the example above, can prove very expensive and exceed the cost of more common infections by several times over. Nevertheless, the difficulty of systematically calculating costs in such cases means that they are rarely studied or that costs are calculated using the expert estimate method. Once the cases have been selected, the cost indicators should be determined. These have been classified as direct and indirect costs. Direct costs* are those incurred during the hospital stay and are relatively easy to quantify. The most common are days of hospitalization, use of antimicrobials, surgical reinterventions, treatments, visits by professionals, and the need for isolation. Indirect costs are the social costs secondary to having had developed a hospital infection, such as lost work, loss of function, transfer of family costs (money that the family had programmed for some activity that was used in connection with the hospital infection—for example, to visit the patient), suffering, and death. Indirect costs are very difficult to quantify, and most studies are limited to calculating the direct costs. All costs studies should yield an economic indicator standardized in local or international currency in order to permit comparisons between facilities and classes (for example: between days of hospitalization and antimicrobial use). However, the local cost of a class can vary over time, between institutions, between types of institutions (for example: public or private) or between countries; thus, it is recommended that, in addition to the economic cost, the volume of the class be included—that is, not only the cost of the excess hospital stay but also the number of days of excess hospital stay. Patients with hospital infections die more frequently than those without them. Some hospital infections, such as bacteremia and pneumonia, are associated with higher premature death. Hospital infections are more common in seriously ill patients, who face a greater risk of dying in the first place and whose hospital stays are more expensive as a result of their disease. Premature death can actually reduce direct costs by shortening the length of hospitalization. This effect must be considered; thus, the majority of cost studies are confined to patients who survive, at least up to their discharge from the hospital.