An ASC patient may acquire an HAI from bacteria or viruses contaminating, for example, the hands of a health care worker or a needle or tube used to deliver medicine, fluids, or blood. These bacteria or viruses may include those responsible for such illnesses as staphylococcus infections and hepatitis. Two agencies in HHS have activities under way to prevent, control, or monitor HAIs. CDC—a key HHS agency for research and programs designed to prevent HAIs—has issued 13 guidelines relevant to infection control and prevention in health care settings. In these guidelines, which are based on scientific evidence, CDC recommends practices for implementation to prevent HAIs. Practices recommended to prevent or control HAIs include, for example, appropriate isolation of infected patients in health care facilities, proper sterilization of equipment, appropriate provision of antibiotics to patients before surgery, annual vaccination of health care personnel for influenza, and hand washing or the use of alcohol-based hand rubs. CMS is responsible for ensuring that ASCs that are certified as suppliers of Medicare-covered services comply with its requirements for infection control. For most ASCs, this occurs through the state-administered standard survey process conducted by state survey agencies under contract with CMS. ASCs may choose instead to undergo accreditation by a CMS-approved accrediting organization. CMS-approved accreditation programs for ASCs have standards that meet or exceed Medicare’s standards. Accrediting organizations are to conduct periodic surveys of ASCs to assess their compliance with the standards established by the accrediting organization, including those related to infection control. The state survey agency or accrediting organization assesses compliance through direct observation of activities in the facility and review of its policy documents. If an ASC opts for the CMS state-administered survey process, a state surveyor uses CMS’s survey guidance to conduct the state’s compliance review of the ASC. We identified five disparate sources of HAI data, all of which differed from one another in the types of HAI information they collected. However, none obtained its data from a nationally representative random sample of ASCs, and therefore none could be used to develop national estimates of HAI outcomes or compliance with infection control practices that affect the risk of acquiring HAIs in ASCs. Two federal data sources—CDC’s NHSN and CMS’s ASC pilot study—provided the most detailed information on HAI outcomes and infection control practices, respectively. We identified five disparate data sources that currently collect data on HAIs in ASCs. HHS operates two of these data sources—CDC’s NHSN and CMS’s ASC pilot study. Two are maintained by professional associations— the Ambulatory Surgery Center Association’s Outcomes Monitoring Project and the American Association for Accreditation of Ambulatory Surgical Facilities, Inc. (AAAASF) Internet-based Quality Assurance and Peer Review Reporting System. Finally, the state of Missouri collects data on HAIs in ASCs through its Missouri State HAI Reporting System. (See table 1.) The five data sources do not provide nationally representative information on HAIs in ASCs. In order to provide a basis for a nationwide estimate of risks of HAIs in ASCs, a data source would need to collect its data from a nationally representative random sample. None of the five data sources does so, and therefore it is not possible to generalize from their results to the nationwide population of ASCs or patients that they treat. Consequently, each of these data sources provides information only about the facilities that actually submit data to it and cannot reliably be used to describe other facilities. In terms of their coverage across ASCs, each of these data sources collects information on HAIs from a relatively small proportion of the 5,100 ASCs in the United States. The coverage ranges from the 26 ASCs that most recently reported data to the state of Missouri to about 650 ASCs reporting to the Ambulatory Surgery Center Association’s database. Moreover, which ASCs are included in each of the databases is determined by highly variable criteria. They include, depending on the database, a decision by the individual ASC to voluntarily participate, membership of the ASC in a particular professional association, and selection of an ASC based on its geographic location in a particular state. For example, all the ASCs in the ASC pilot study are from Maryland, North Carolina, or Oklahoma because those states volunteered to participate in the study, and the ASCs covered by the two professional organizations and the state source are taken from narrowly defined subsets of ASCs, that is, from member ASCs or from ASCs within a certain geographical area, respectively. The five data sources also vary in the type and level of detail of the information they collect. NHSN, AAAASF, and Missouri’s system collect data on individual patients, and the ASC pilot study and the Ambulatory Surgery Center Association’s database collect data that are aggregated to the facility level. Four of the five data sources—all but the ASC pilot study—collect information on patient outcomes, specifically rates of SSIs. However, of those four, only the federal NHSN and state of Missouri databases employ standard CDC definitions to identify cases with SSIs based on these criteria. The two professional association databases leave identification of SSIs to individual physician judgment. Both professional association databases also collect information on one or more process measures. One of these databases focuses on a practice intended to prevent SSIs—the routine use of antibiotics prior to surgery—and the other collects information on the treatment of SSIs. The ASC pilot study collects data solely on process measures. The most detailed data are provided by the two federal data sources, NHSN—the most widely recognized source of outcome data on HAIs—and the ASC pilot study. The pilot study collects data on a broad range of process measures assessing the implementation of infection control practices, such as those intended to prevent the transmission of infections through appropriate hand hygiene, injection, and sterilization procedures. A key feature of NHSN is that it collects clinically sophisticated and standardized data on HAI outcomes. Facilities that participate in NHSN, including ASCs, agree to collect and submit information on HAI outcomes, such as SSIs, according to defined protocols and standardized definitions. CDC developed detailed protocols for NHSN that specify the medical record and laboratory data needed to identify and categorize HAIs in accordance with CDC’s standardized definitions. These protocols are widely accepted by infection control professionals because they make the data in NHSN clinically relevant and comparable across the facilities submitting data to NHSN. At the same time, the data collection procedures used by NHSN can be labor intensive and technically complex for some users. For example, one expert reported that ASCs found data submission to NHSN to be time-consuming and that an ASC might opt out of the program if its demands on staff time and other resources became excessive. Although the number of ASCs currently submitting data to NHSN is unknown, it is likely to be small. NHSN has national open enrollment for multiple types of facilities. However, until September 2008 only hospitals and outpatient hemodialysis centers could enroll in NHSN. In September 2008, CDC launched a new release of NHSN that enabled freestanding ASCs that were separate from hospitals to enroll. Enrollment of ASCs may increase over time, especially if more states enact programs mandating public reporting of HAIs by ASCs using NHSN. According to a CDC official, CDC has a facility survey under way that will enable it to determine the number of ASCs that enroll in NHSN, but this official does not expect to have results available from this survey until spring 2009. Nonetheless, independent of the number of ASCs that participate in NHSN, the processes by which ASCs enroll make NHSN data nonrepresentative of ASCs nationwide. Some ASCs enroll in NHSN voluntarily, and others are required to enroll by mandate of their state government. Because NHSN uses voluntary and mandatory selection procedures, the selection of ASCs for participation in NHSN is nonrandom. This lack of random selection precludes a projection of its results to any ASCs that do not participate and generalization to the national population of ASCs. The ASC pilot study examined the potential for using CMS’s standard surveys to collect information on ASCs’ implementation of specific infection control practices. Under the pilot study, CMS modified the standard survey process by introducing two innovations—the incorporation of a CDC-developed infection control assessment tool and direct observation by the surveyor of a single patient’s care from start to finish of the patient’s stay. CDC officials also provided training for state surveyors on using the tool and developed plans to analyze the infection control data obtained with the tool. A CMS official told us that CMS would consider making changes to CMS’s standard survey process for ASCs after reviewing planned CMS and CDC analyses of the pilot study results. The surveys conducted under the pilot study collected more detailed information on practices that affect the risk of HAIs in ASCs than have previous surveys of ASCs. CMS’s current survey process requires surveyors to ascertain whether an ASC’s written policies and procedures address certain general topics pertaining to infection control. In doing so, surveyors assess the implementation of these policies and procedures and an ASC’s overall maintenance of a sanitary environment through direct observation and interviews with ASC staff. If surveyors find that either the content of those policies and procedures or their implementation by ASC staff is insufficient to meet CMS’s infection control standard, they submit a deficiency report to CMS that provides a detailed narrative describing the particular conditions or activities in the ASC that created that deficiency. In contrast, the pilot study’s infection control assessment tool focused on specific CDC-recommended infection control practices. The tool is a 12-page document that includes dozens of specific infection control practices, involving such topics as environmental cleaning, disinfection, sterilization, and injection safety. CDC researchers who developed the tool included those practices that they had found were most critical for the prevention of HAIs in the ASC setting.