How do you know if you're doing a good job in preventing surgical site infections? First, you'll have to examine each part of your infection control system including its structure, process, output and outcome. You can hire top-notch surgical and infection control staff to work in facilities that conform with all pertinent building standards (structure), set comprehensive policies and procedures (process), and audit compliance (output), but the only way to accurately gauge how well you're doing is to measure your infection rates directly (outcome). Monitoring this outcome is particularly challenging in an ambulatory surgery setting, where patients depart long before infections normally become evident and any ensuing infection can be a result of post-discharge as well as intra-op factors,
[1, 2] but this is the most meaningful approach to validate and fine-tune preventive efforts.
What Makes a Successful Program?There's more to interpreting infection rates than just looking at whether any numbers calculated seem low or not. The worst way to produce low infection rates is to rely on entirely passive surveillance methods,
[3, 4, 5, 6, 7, 8] and ignore the fact that patients might not be able to identify wound infection accurately.
[9] These factors can lower sensitivity (the proportion of true infections identified) of a surveillance program. On the other hand, encouraging widespread informal reporting without due attention to diagnostic criteria (and experience in their use) can inflate the rate by including misclassified "false positive" cases.
[10, 11] Therefore, the first step is to consider the quality of an infection surveillance system itself.
[12, 13, 14] One hallmark of a successful program is whether surgeons actively participate. While some surgeons may be happy to participate,
[15] there may be tensions between those who conduct surveillance and those whose work is under surveillance.
[16] It's also critical that the surveillance results are proven to be meaningful and accurate. A complete guide to creating effective surveillance programs is beyond the scope of this article, but you could start by reviewing a consensus document from organizations representing epidemiologists, infection control professionals, and surgeons,
[12] then check the most recent guidelines on preventing surgical site infection.
[17] Overviews providing comprehensive practical advice on surveillance program components and options are also useful.
[18, 19]Interpreting ResultsIf a surveillance system is adequate, the next step is figuring out how low a rate is good or how high a rate is not good.
[20] One approach is to try "benchmarking" rates against other facilities. Another approach is to monitor trends within a facility through techniques like statistical process control (SPC) charting.
[20, 21, 22] Benchmarking is simply studying peers for the purpose of learning to apply best-in-class practices. For example, just as manufacturers might identify companies that are best at cost-effective on-time delivery in order to emulate their key practices, surgical facilities might study peer facilities that have consistently low infection rates and then emulate their methods for ensuring optimal delivery of prophylactic antimicrobials. Any surgical facility could use published rates or surveillance networks as a first step in deciding whether their own rates are of a reasonable magnitude or not.
Statistical process control is a graphical technique to discern trends and "special cause" variation. Any surgical facility could use SPC to decide when infection rate changes probably reflect random variation and when they signal onset of a trend upward or downward.
Whether you employ benchmarking or SPC, you'll need an appreciation of statistical theory. You'll need to know, for example, if it is reasonable to set a goal of always being lower than the mean or median rate of other facilities. By definition, half of all measurements rest above and half below the median, so by random chance alone an individual facility should spend some time on each side of that average value. Conversely, you'll need to determine how many points in a row above (or below) the average constitutes a trend. You may want to consult the an epidemiologist to help you interpret your data.
Developing an Improvement ProgramIf surveillance results suggest room for improvement, you'll need to investigate to confirm that something more than random chance is associated with performance variations and to focus improvement efforts. Major determinants of infection risk are:
- first and foremost, skill of the surgeon;
- second, discipline of the team;
- third, preparation of the patient; and
- fourth, adequacy of the surgical environment.
The nature of pathogens involved in surgical site infections and rates and patterns of infection all provide clues as to which determinant(s) might require improvement. It's helpful to have some knowledge of clinical and environmental microbiology, as well as familiarity with outbreak investigations published by epidemiologists, to aid in interpreting these clues. For example, streptococcal wound infection suggests an exogenous human source, so a single case of group A or a cluster of group C strep infections should prompt investigation of surgical team members.
[23, 24, 25, 26] On the other hand, staphylococcal wound infections also tend to arise from human sources, but are as likely to come from a patient's own nasal flora (endogenous) as they are to be transmitted from surgical staff (exogenous source).
[27] Organisms such as Pseudomonas spp. suggest a wet reservoir,
[28, 29] while fungal infection of surgical wounds could represent transmission from drier environmental sources such as ventilation ducts.
[30] Skill and experience of surgeons also matter, given that predisposition to infection rests in the extent of tissue trauma, dead space, blood loss, security of closures, duration of procedures, etc., although few studies have examined experience per se.
[31] Other well-established components of programs to prevent surgical site infection include:
- Aseptic practices to block transmission of organisms from reaching surgical wounds;
- Antiseptic measures to reduce the number of microbes on scrubbed hands and prepped surgical sites;
- Treatment of concurrent infections prior to surgery, as well as appropriate prophylaxis during surgery.
These components protect against sporadic as well as epidemic infection, protect both patients and staff from infection, and to a certain extent may ameliorate deficiencies in surgical prowess, but in many cases, there's room for improvement. There have been many recent cases of antibiotics being used improperly or at the wrong time, contributing to drug resistance. Several studies of bloodborne pathogen exposures during surgery conclude that a large proportion of the incidents were preventable. If you suspect noncompliance, it's important to monitor the rates and reasons for it and act upon it in a timely and appropriate manner.
In recent decades, efforts to prevent infection have shifted to a balance between staff, patient, and procedural issues rather than emphasizing dogmatic restrictions coupled with microbiological monitoring of surgical environments. This may appear to diminish the importance of the environment in which surgery is practiced, but it makes proven environmental safeguards even more critical than ever. Recent changes announced by the FDA concerning regulating reuse of single-use items reflects just such an area of sharpened focus.
[32, 33]Ideally, you know that you're doing a good job at preventing surgical site infections because you are served by applied research through your infection surveillance program. It should be a cornerstone of the continuous quality improvement program that enables you to select cost-effective approaches best suited to satisfy your facility's staff and patients.
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