Study Examines SSI Risk Factors for Abdominal Hysterectomies


Investigators studied the risk factors for surgical site infections after abdominal hysterectomy procedures using NHSN data and diagnosis codes from administrative data.

Abdominal hysterectomies are a common surgery, and certain risk factors are associated with the procedure. A recent study published in the American Journal of Infection Control, titled “Risk factors for surgical site infection after abdominal hysterectomy, New York State, 2015-2018,” discusses what risk factors lead to the highest number of surgical site infections (SSIs).

Boldt Tserenputsag, DrPH, MPH, director of the data unit, Bureau of Healthcare Epidemiology Infection Control for the New York State Department of Health, and lead author of the study, spoke to Infection Control Today® (ICT®).

ICT: Can you give us a summary of the key findings and why they're important?

Okay, so the study we're going to talk about is a report on risk factors associated with surgical site infections following abdominal hysterectomy in New York State between 2015 and 2018. The New York State Department of Health monitors surgical site infections using NHSN, the National Healthcare Safety Network since 2006, and monitors several serious surgeries for wound infections. Abdominal hysterectomy is one of the procedures New York State tracks for wound infections.

Hysterectomy is surgery to remove the uterus and is the second most common surgical procedure for women after cesarean section. As we know, there are 2 types of hysterectomy procedures, abdominal and vaginal. Only abdominal hysterectomy surgical site infections are reportable in New York State [since we began tracking] infections in 2012. So, in New York State, usually around 15 to 17,000 abdominal hysterectomy procedures are performed. Our study included 4-years’ worth of data on hysterectomies, including over 70,000 procedures reported in NHSN.

To get more information on patients, we used a building data “SPARCS,” which stands for Statewide Planning and Research Cooperative System, and the aim of this study was defined risk factors for surgical site infection following a hysterectomy. Surgical site infection associated with hysterectomy is not very common. Around 1% of the patients were diagnosed with the infection in New York City hospitals after abdominal hysterectomy.

We identified several factors which could influence wound infection. These risk factors were younger age under 45, open approach (not laparoscopic) procedure, contaminated or dirty wound class obesity, longer duration of the procedure, higher ASA score by American Society of Anesthesia, gynecological cancers, and diabetes.

So why it's important to study the surgical site infections after a surgery that lead to additional morbidity and mortality with longer hospital stays and higher health care costs. Wound infections can be superficially like skin infections or deeper infections with spreading to muscle [or] even organ spaces. In severe cases, it can progress to sepsis, even to death. So that's why it's important to identify risk factors [that] influence somebody's risk for wound infection after a surgery…or reduce particular risk factors to prevent an infection.

ICT: What is the practical application for your study for infection preventionists?

Hysterectomy is an operative procedure. So it's unavoidably associated with a relatively higher risk of infection because the procedure breached the genital tract, which is not sterile. So these factors are less modifiable, but other factors can be modified or reduced. Addressing patients’ comorbidities and counseling patients on risk factors such as [being] overweight, smoking, diabetes, or hypertension may be needed. Controlling or reducing such factors may bring down somebody's risk for complications, including wound infection. For example, if a patient has poorly controlled diabetes or uncontrolled high blood pressure, these conditions better be stabilized preoperatively to prevent further complications after surgery. So, if we can reduce these factors, it will lower the ASA score and subsequently lower the risk of wound infection.

Many studies, including ours, report that laparoscopic procedures are safer for patients. So laparoscopic approach should be preferred when it is feasible. On the other hand, laparoscopic procedures tend to be longer. So preoperative planning should be rethought, especially when we're dealing with patients with multiple risk factors. Finally, antibiotic prophylaxis and postoperative care should be customized according to the patient's condition and risk factors. So it's teamwork between surgeons and infection preventionists.

ICT: What results surprised you, if any, in your study?

Many of the risk factors didn't surprise me. One little surprise was that the transfusion for blood loss was significant in the bivariate [analytics], but when we included all the variables [it was not significant]. But so the reason could be where we got information from. We got it from building a database, so [the data] could be incomplete, or so there could be issues.

And another little bit of surprise was younger women with increased risk compared to middle-aged women. Most postoperative complications are higher in elderly patients [because] the patients have more comorbidities, and the recovery time is longer. They tend to have complications after surgery. But in our study, after controlling all the factors, the younger age group [showed] a significantly higher risk for wound infection.

I wondered, but after I think about the nature of the hysterectomy, maybe it's not a surprising finding. Because abdominal hysterectomy, especially an open laparotomy procedure, in young women [is] performed if the condition is very severe; most of the time, it's performed [as] emergency surgery after a life-threatening blood loss or something like that. So that's this woman who has open, long laparotomy procedures; they most likely have severe blood loss, infection, advanced cancer, or other conditions requiring abdominal hysterectomies. Maybe more studies are needed on that.

ICT: Do you have any future research coming on this research?

I would like to look into a bit more or more detail when there is an opportunity because of the limitations of the datasets sources we use. We did not or could not look at other important factors, especially the surgery-related factors. For example, [one] type of hysterectomy—a partial hysterectomy—removes only the uterus and preserves the other organs. But a more complicated radical hysterectomy removes all the uterus, cervix, ovaries, fallopian tubes, and part of the vagina, and other structures and organs are removed. This type of procedure requires more surgery time, that may be associated with a higher risk of wound infection. Maybe we need to look at the type of procedures when we do a study in the future. Also, the status and types, and locations of the cancer may have different influences on infection. If we would do a study, we would look into this practice, but for now, we [don't] plan to study at this point.

ICT: Is there anything else that you'd like to add?

[I] maybe wanting so currently cancer diagnoses not reported in NHSN with a surgical procedure, diabetes, emergency or electives, surgery status is there, and BMI is there, but cancer diagnosis is not there. So our study and other studies identified cancer as a risk factor for wound infection for hysterectomy. Other studies also reported that cancer is a risk factor for wound infection for other types of procedures. So maybe [identifying] cancer status in science reporting should be evaluated. So it could be beneficial for better risk adjustment.

Yes, I have one more thing to add. I think to my coauthors. This study was a result of the hard work of talented infection prevention specialists and data analysts. Last but not least, I also want to express my gratitude to infection preventionists in New York City hospitals for the fight against infection and for the timely and accurate reporting of the infection data for us to analyze. And finally, thank you for the opportunity to talk to you about my work.

You are most welcome. It's been an honor. Thank you so much.

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