One-third of orthopedic trauma patients did not meet new CDC SSI definition

Patients with early vs late infection were not significantly different other than the need for flap coverage.

About one-third patients at a level 1 trauma center did not meet the CDC definition for acute postoperative infection following fracture fixation, a presenter at the American Academy of Orthopaedic Surgeons Annual Meeting said.

The CDC in 2016 changed the timeframe of its the definition of deep surgical site infections (SSIs) from within 1-year of the initial surgery to within 90 days of the initial surgery.

“[There] were no patient-specific factors that differed significantly between these patients [infected after 90 days] and those that did become infected within 90 days,” Brent T. Wise, MD, from the department of orthopedics at Emory University, said. “The need for flap coverage may make patients more likely to present late with an infection and furthermore, [those] with Hepatitis C or HIV, or those who required admission to the ICU, may present late with an infection compared to a control group. Males, or [those with] fractures of the pelvis or acetabular of the hip may present earlier.”

Retrospective review

At the R. Adams Cowley Shock Trauma Center/University of Maryland, which is a level 1 trauma center, Wise and colleagues performed a retrospective review of 452 patients with deep SSIs following fracture fixation. Patients were divided into 308 patients in the early infected group who had an infection within 90 days of index surgery and 144 patients in the late infected group who had an infection that occurred after 90 days from the index surgery. After they performed a literature review, investigators collected data on 21 factors considered theoretic risk factors for post-fracture infection.

Univariate analysis was used to compare the risk factors between the early and late infected groups. Subsequently, multivariable analysis was performed to create prediction models for both groups.

Investigators randomly selected 594 patients and used their factors to build infection prediction models for infection within 90 days and infection after 90 days. They then used a stepwise backward selection process to determine predictors. To determine whether differences existed between early infection and late infection, the investigators modeled the two outcome groups against each other.

Early vs late infections

Study results showed that of the 452 infections identified, 32% or 144 infections occurred after 90 days. Logistic regression models for the early infection group vs. the late infection group showed there were no statistically significant patient factors. The only injury characteristic that differed between the two groups was the need for flap coverage due to an initial soft tissue injury. Patients in the late infected group had a greater chance of needing a flap than patients in the early infected group.

“[Being] male and having a fracture of the pelvis and acetabulum of the hip may be predictors for earlier infection as these factors were statistically significant in the early vs. control model but were not so in the late vs. control model,” Wise said. – by Monica Jaramillo

Reference:

Wise BT, et al. Paper 15. Presented at: American Academy of Orthopaedic Surgeons Annual Meeting; March 6-10, 2018; New Orleans.

For more information:

Brent T. Wise, MD, can be reached at 201 Dowman Dr., Atlanta, GA 30322; email: brent.wise@emory.edu.

Disclosure: Wise reports no relevant financial disclosures.