Surveillance and Diagnosis: Surgical Site Infections

BY DANIELLE SCHEUER, MD, MSC, FHM

Despite all preventive attempts, SSIs can and do occur. Therefore, a systematic mode of surveillance and diagnosis of SSIs is critical for early detection/treatment of the disease and for the identification of trends and patterns that warrant further interventions.

As mentioned above, the clinical presentation depends on the type of SSI. According to the NNIS, these infections are classified as incision or organ/space infections, and incision infections are further divided into superficial (skin and subcutaneous tissue) and deep (deep soft-tissue muscle and fascia).

Incision infections account for two-thirds of all cases, and organ/space infections account for the remaining one-third.

Signs and symptoms of infection present within a week in 50% of patients and within 2 weeks in 90% of patients. The CDC definition, however, delineates any infection that occurs within 30 days of the operation (and up to a year if related to an implant) as an SSI.

Signs and symptoms usually include localized pain, erythema, drainage, subcutaneous swelling, foul odor, fever, and elevated WBC (or other markers of inflammation such as ESR or CRP).

The SHEA/IDSA guidelines include a list of strategies to survey and detect SSIs. They recommend using the CDC NNIS and the National Healthcare Safety Network definitions for SSIs. Surveillance can be accomplished by the direct or the indirect method. The direct method involves daily observation by a trained health care provider and is the gold standard, but is impractical because of the resource utilization required. Alternatively, the indirect method involves a few options, including review of microbiology and patient records, surgeon/patient surveys, screening for readmissions, or screening for diagnosis codes/operative reports. Indirect methods have been shown to have good sensitivity and specificity and are both acceptable and more practical than is the direct method. It is preferable to use an automated surveillance system to reduce the need for manual labor and enhance reliability. Postdischarge surveillance is very difficult to employ, and no standardized method has been shown to have reliable sensitivity or specificity, including surgeon surveys. For the short term, creation of a reliable inpatient tracking system for inpatient or readmitted SSIs will suffice.

The surveillance team should consist of trained personnel who can prospectively apply the definition of SSI. The surveillance team should have a number of responsibilities:

1. Develop a database of their surveillance, based on the appropriate indirect method chosen.
2. The database should include the collection of appropriate denominator data (number and types of surgeries performed).
3. The data should including a risk adjustment, based on national benchmarks, to determine the observed/expected rates, or the standardized infection ratio (SIR).
4. The team should prepare periodic reports. The reports should be able to identify SSI trends (by location, surgeon, organism, etc.). The reports should also be used to anonymously provide data on institutional benchmarks/trends to physicians and executive leaders and to provide direct feedback to each surgeon/division/chief on individual rates. Regular benchmarking and feedback to the surgeons are critical parts of the surveillance program.
5. Another important function of the surveillance team is mass education of providers (doctors, nurses, operative personnel) in the prevention and surveillance methods for SSIs.
6. The team should also function to educate patients and families in the definition and recognition of SSIs and in strategies for prevention. Education materials can be found at SHEA, the IHI, and SCIP.
7. The surveillance team should be responsible for not only this internal reporting of outcome measures (SSIs) but also for facilitating external reporting of SSIs to local, state, and federal agencies.
8. The team should also be responsible for internal and external reporting of the process measures required by SCIP and CMMS, as well as any other relevant process measures found to be deficient in a gap analysis of performance (such as smoking cessation counseling).