Proactive Risk Assessment of Surgical Site Infection in Ambulatory Surgery Centers

Chapter 3. Risk-Informed Interventions

One of the most important goals for this project is to identify an intervention that has the greatest likelihood of mitigating the risk of SSIs. In this chapter, we detail Step 6, "Design a Risk-Informed Intervention," by describing:

  • How we used importance and criticality measures, along with the cut sets, to inform the selection of an intervention.
  • The targeted event(s) for the intervention.
  • A description of the proposed intervention.
  • Recommendations for implementation.

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Importance Measures

Importance measures are used to rank the most significant individual risks, based upon their contribution to the top level event (SSI), as a means of improving system performance. These measures help to assess the criticality of the risk in the model by assessing either the absolute risk, the risk's relative importance within the model, or the risk's frequency in the model. Commonly used relative importance measures in risk assessment modeling include the criticality, Birnbaum, and Fussell-Vesely measures.8 These measures anchor an individual risk estimate within the context of the other risks in the model. For example, the Birnbaum measure ranks the risks based upon the relative contribution of individual component failures in a system, and the Fussell-Vesely measure is a linear indicator of risk that accounts for the fractional contribution of a risk element to the total system for all scenarios under study, based upon the failure of an individual component. On the other hand, the criticality measure is a measure of absolute risk, which identifies the independent risk contribution of a basic event. For example, assuming that the top event SSI occurs, the criticality of basic event A is the probability that the top event is a result of basic event A. This allows the team to understand the fundamental components of a system's liability.

The importance measure selected depends, in part, on the type of model created and the purpose of the modeling exercise. For this study, we focused on the criticality measure, because this measure permitted the rank ordering of the most critical contributors to the very rare event of SSIs and facilitated the identification of interventions that are most likely to improve system performance.

Exhibit 11 presents the events from the ST-PRA model ranked in order of criticality. For example, "Event 642 Fail to protect the patient effectively,"ranked as the most critical unique event, with the highest independent contribution to the occurrence of SSIs of 0.5187.

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Event(s) Targeted for Intervention

The criticality analysis provided a foundation for understanding the basic level events with the highest probability of contributing to the top level event. However, the real power of ST-PRA stems from the combinations of events and probabilities to identify critical paths leading to the occurrence of an SSI, as depicted in the minimal cut sets in Exhibit 9. Using both the criticality analysis and cut sets to identify the intervention ensures that the selected intervention will have the greatest impact in reducing SSIs.

To be successful, it is also important to consider the ease of implementation, the likelihood of achieving substantive improvement based on the intervention, and the level of effort necessary to effectively implement these interventions within an existing system (i.e., ASC environment). As with other quality improvement efforts, the most feasible intervention is the one that combines ease of implementation, has the greatest likelihood to yield an impact, and is the most resource conservative.

Due to its high criticality score and the fact that it appeared in four of the five top cut sets, "Event 642 Fail to effectively protect patient," and its component events are recommended as the focus for intervention development. The most important components that comprise this failure, as indicated by their contribution to the risk of developing an SSI, include:

  • Fail to prepare the skin appropriately preoperatively.
  • Antibiotic-related failure.
  • Staff not well-trained in infection control practices.
  • Glove puncture.
  • Fail to remove watch, jewelry, or artificial nails.

Interestingly, several of these components are included as infection control requirements by the Joint Commission or the Centers for Medicare and Medicaid Services (CMS) accreditation and compliance processes in the hospital surgical environment (i.e., there are specific infection control standards regarding the wearing of jewelry and artificial nails, use of antibacterials, and other associated infection control practices). Although not required in ASCs, some facilities have adopted these policies. For example, hospital-affiliated ASCs tend to incorporate their hospital's policies as their own; however, there can be great variability in how the policies and procedures are monitored and enforced, further highlighting this set of events as the target for a potentially valuable intervention.

The original risk of developing an SSI is estimated by the model as 0.0044, as noted previously (i.e., 44 out of 10,000 cases will develop an SSI following surgery). Because improvement efforts can never be 100 percent successful at mitigating risk, we examined the variable impact of an intervention using values of 25, 50, and 75 percent reduction in noncompliance rates. Exhibit 12 presents the new probability estimate for an intervention targeting each component intervention to reduce the occurrence of an SSI. For example, "Event 30 Fail to prepare the skin appropriately" has an original probability estimate of 0.1250. If providers reduce the current noncompliance rate of 12.5 percent by 25 percent, 50 percent, or 75 percent the probability risk for this single event would be reduced to 0.0938, 0.0625, or 0.0313, respectively, as shown in Exhibit 13.

Because the targeted event is comprised of multiple, related issues, the intervention can be designed to address each of these components in the aggregate. This approach affords greater opportunity to demonstrate risk mitigation than developing an intervention that targets only one of these risk points. The impact of each of these combinations at different impact levels are presented in Exhibit 13. For example, if an ASC chooses to focus on improving skin preparation practices to appropriate levels, the intervention would reduce the likelihood of that risk factor from 0.125 to 0.0625, if the noncompliance rate was cut in half (i.e., reduced by 50 percent), as presented in Exhibit 13. If the ASC selected interventions that targeted both the failure to prepare the skin appropriately and training for staff in infection control practices and expected only a 25 percent reduction in noncompliance rate for each, the probability of an SSI would actually be further reduced to 0.0039, as presented in Exhibit 13.

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Proposed Intervention

Based on the results presented in Exhibits 12 and 13, we propose an intervention aimed at "Event 642 Fail to protect patient," and focusing on all five major components of this cut set. Specifically, the intervention is designed to target skin preparation practices, proper administration of antibiotics, staff training in infection control practices, how to prevent glove punctures, and procedures to ensure removal of watches, jewelry, and fake nails.

When designing an intervention to improve patient safety, it is important to look for opportunities in which the intervention can be hardwired into the system of care. As much as possible, these interventions should focus on aspects that the provider can control (as opposed to relying on patients to comply with instructions, for example), should be integrated into the process of care, and should include redundant process steps to minimize the occurrence of single-point failures.

When designing the intervention, the investigative team considered both the results from the sensitivity analyses and information gleaned through the site visits. These results pointed to focusing on the two major processes within the ASC environment that may impact the way in which care is provided, namely the practices employed to prevent infections and the information shared across members of the provider team, starting with the primary care physician all the way through the postoperative nurse. As a result, the proposed intervention targets these two important processes of patient care:

  • Infection control practices.
  • Communications between health care providers.

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Infection Control Practices

A major aspect of the intervention involves integrating better standards for infection prevention practices into the daily care provided at ASCs. As a result, we recommend that guidelines for infection control practices at ASCs, modeled after the guidelines provided to hospitals, be developed. Furthermore, accompanying training for ASC staff should include the following:

  • Prevention of preoperative infection transmission (e.g., hygiene, infectious waste, personal protective equipment, infectious patients, prevention of patient-to-patient transmission; assessment of risk factors for SSIs; risk procedures).
  • Prevention of intraoperative infection transmission (e.g., surgical disinfection and antisepsis, skin preparation, disinfection in the surgical environment).
  • Prevention of postoperative infection transmission (e.g., dressing the postoperative wound).

For example, the guidelines may include an antibacterial prophylaxis protocol that consists of several important components:

  • Timing for drug administration.
  • Proper drug selection.
  • Re-administration of the drug after a specified period of time.
  • Specific instructions for proper dosing for obese patients.

Another important example is surgical preparation and draping, a longstanding surgical technique. The important elements of this procedure should be ensured by the team as they prepare for the performance of the surgical procedure. In much the same way that Bundles of Care have extrapolated care from the operating room to the bedside for the performance of central venous catheters, we believe that there is an opportunity to readdress the way in which the surgical preparation and draping is performed. After residency, surgeons may never again be critiqued on their technique in this area, and the orientation procedures for surgical staff in ASCs are highly variable. As a result, the quality and consistency by which ASCs perform surgical preparation and draping is unknown. However, we do know that it is the procedure that has the highest opportunity for incorporating risk for an SSI into the model. Therefore, the intervention should include opportunities for staff technique to be observed, standards incorporated into a bundle, and staff trained on the proper technique to ensure consistency across providers and personnel in the ASC environment.

Therefore, we recommend that the ASC Bundle of Care provide specific guidance about infection control practices that ASCs should have in place and focus particularly on the critical issues identified through this study that significantly contributed both individually and in combination to an SSI. Namely, we recommend that the bundle address the following issues:

  • Identification of high risk patients (e.g., diabetes, MRSA, obesity).
  • Procedures to ensure removal of jewelry, watches, and artificial nails.
  • Guidance on routine double gloving and proper response to glove punctures.
  • Skin preparation practices including antisepsis and draping.
  • Proper administration of antibacterial agents.

Further, we recommend that the bundle be implemented within a broader infection control plan, affording opportunities for auditing performance and subsequently supporting improvements in patient care within the ASC environment.

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Communications Among Health Care Providers

The next piece of the intervention involves improving the communications across the various providers, including the physicians, surgeons, and ASC preoperative, operative, and postoperative staff. During the site visits, we discovered several areas where communications tended to break down such as between the ASCs and physicians' offices during the preoperative phase of care. For example, we know that the ASC environment is a valuable and safe venue for receiving care for a large portion of the population but that it may not be the appropriate or feasible option for everyone (e.g., we know that most ASCs cannot accommodate morbidly obese patients). As a result, we propose that efforts also be directed to improve the communications between health care teams to better identify those patients who would be better served receiving care in an alternative environment such as the hospital where they have the tools and techniques in place to better care for patients such as the morbidly obese.

One way to improve communications is to create a checklist to be used by the nurse during the preoperative screening phone call to ensure that major risk factors such as obesity and poor blood glucose control are properly identified. A referral back to the surgeon should be performed for any concerns known to increase a patient's risk for developing an SSI (e.g., smoking, diabetes, and obesity) to ensure optimal control during surgery. This communication should also be shared with the anesthesiologist and the patient's primary care physician. A conversation should occur between the health care team members to determine whether the patient can proceed with surgery safely within the ASC environment, if inpatient surgery is the more appropriate option, or if the procedure should be done at all. These can be handled during preoperative huddles early in the morning or prior to the case.

In addition, ASCs should establish stop-gap measures that prevent surgery from occurring for patients with multiple known risk factors who present out of control on the morning of surgery (e.g., blood glucose levels out of control, uncompensated congestive heart failure [CHF]). To accomplish this, a variety of TeamSTEPPS® tools can be considered. First, structured communication in the form of an SBAR, for example, might be used for a nurse to highlight a particular risk point to a surgeon. Alternatively, When a particular issue becomes a patient safety concern (e.g., when a patient's chronic obstructive pulmonary disease is out of control preoperatively), the nurse might consider the Two-Challenge Rule or the CUS tool ("I'm concerned, uncomfortable; this is a safety issue.") to get the surgeon's or anesthesiologist's attention.

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Intervention Implementation

As has been experienced in other health care settings for other initiatives (e.g., patient safety regulations), an important first step to improving outcomes—in this case, reducing the risk of SSIs, improving infection control practices, and improving communications—is to institute regulations to ensure that: providers are properly trained on infection control practices; staff do not wear watches, jewelry, or artificial nails; multiple components for antibacterial prophylaxis, including proper timing of administration, occur.

We propose that ASCs may be motivated to improve their infection control practices if a regulatory body with oversight of the ASC environment provides recommended guidelines or requirements. Because Joint Commission accreditation is currently voluntary for ASCs, the CMS should take an active role in better understanding the ways in which care can be improved in the ASC setting, especially with respect to infection control practices, and then provide this information to the public to assist with their decision regarding surgical options.

This piece of the intervention requires active participation by both the Joint Commission and CMS, and would be consistent with their current role in monitoring the care provided in these settings. For example, CMS has already established regulations regarding infection control in the hospital environment, which should facilitate the transition and tailoring of these regulations to the ASC environment. CMS also already plays an active role in the care received by its beneficiaries in ASCs and sponsors the integrated data sources necessary to investigate ASC infection risks at the patient level.

We believe that health care providers in ASCs want to improve the care provided to patients and prevent SSIs. To that end, regulatory requirements can be helpful in providing a standard, which currently does not exist for ASCs, for ensuring that providers take the necessary steps to protect their patients. Another possibility is to leverage the interest that ASCs have in ensuring quality patient care by engaging them as active partners in implementing the new requirement. In this way, AHRQ will build support for this initiative from both directions, from those who provide oversight of the regulations and from those who will be implementing these new practices.

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Page last reviewed April 2013
Page originally created April 2013
Internet Citation: Chapter 3. Risk-Informed Interventions. Content last reviewed April 2013. Agency for Healthcare Research and Quality, Rockville, MD.