Background

Surgical site infections (SSIs) remain a prevalent postoperative complication, occurring in approximately 300,000 patients annually in the United States. SSIs cause significant healthcare burden for both patients and providers, as they often require reoperations and increased hospital stays.

SSIs are associated with substantial costs and financial burden, with estimates ranging from $3 to $10 billion annually. With United States healthcare spending now over 17% of the gross domestic product (GDP), developing methods to reduce SSI rates is imperative.

In spine surgery specifically, SSIs are a known potential complication, particularly when instrumentation is employed. Most studies report SSI incidence following spine surgery to be between 0.5% and 5%.

Objective

This study investigated the effects of developing and implementing an infection prevention protocol augmented by increased physician awareness of spinal fusion surgical site infection rates and the resultant cost savings.

Methods

The study conducted a 10-year cohort clinical investigation at a single tertiary spine care academic institution. Within the department of neurological surgery, Surgical Care Improvement Project (SCIP) measures had been in place since 2004, with documentation of infection rates for spinal fusion surgery since 2007.

Timeline of Interventions:

• January 2007 – February 2011: Baseline period with only standard SCIP measures
• March 2011: Preoperative infection control measures implemented:
  • 4% chlorhexidine gluconate (CHG) preoperative bathing for 5 days
  • Nasal screening for Staphylococcus aureus preoperatively
  • Administration of 2% mupirocin ointment for nasal decolonization for 5 days for positive tests
  • CHG-alcohol as the standard preoperative preparation unless contraindicated
• January 2013: Additional postoperative measures implemented:
  • Requiring sterile technique for surgical dressing changes
  • Requiring dressings to be changed daily for 7 days after spine surgery
  • Standardization of dressing changes
• May 2015: Physician awareness program implemented:
  • All attending and resident neurosurgeons informed of their individual, independently adjudicated spinal fusion surgery infection rates
  • Rankings among their peers shared
  • Initiatives discussed in both resident and faculty departmental quality improvement conferences
  • Email notification to the department chair of any newly occurring infections

The study tracked both overall infection rates and rates for neurosurgeons who complied with these measures (protocol group) versus those who did not (control group). Infections were independently adjudicated by infection control staff based on CDC’s National Healthcare Safety Network definitions.

Results

Overall Infection Rates:

• Baseline (Jan 2007-Feb 2011): 1.3% (111 infections/8751 procedures)
• Annual rate rising from 0.8% in 2007 to 2.9% in 2011
• After preoperative measures (Mar 2011-Dec 2012): Increased to 3.3% (69 infections/2108 procedures) despite interventions
• After postoperative dressing measures (Jan 2013-Apr 2015): Declined to 2.3% (108 infections/4676 procedures)
• After physician awareness program (May 2015-Jul 2016): Further declined to 1.5% (22 infections/1474 procedures)
• Significant 54% decline in infection rate from 3.3% to 1.5% when comparing preoperative measures period to final period with all interventions in place (p = 0.0013)

Figure 1: Overall Spinal Fusion Postoperative SSI Rate Trends

A significant decrease in the overall infection rate was observed after the implementation of postoperative infection control protocol (surgical dressing measures) in January 2013 and physician awareness in May 2015. The overall infection rate decreased by 54% from 3.3% to 1.5% (p = 0.0013).

Protocol Cohort Results:

• Baseline (Jan 2007-Feb 2011): 3.0% (64 infections/2108 procedures)
• After preoperative measures (Mar 2011-Dec 2012): Trended upward to 3.8% (61 infections/1622 procedures)
• After postoperative dressing measures (Jan 2013-Apr 2015): Trended downward to 2.9% (93 infections/3260 procedures)
• After physician awareness program (May 2015-Jul 2016): Further decreased to 2.1% (17 infections/829 procedures)
• Significant 45% reduction in infection rate when comparing preoperative measures period to final period with all interventions (3.8% to 2.1%, p = 0.03)

Figure 2: Spinal Fusion Postoperative SSI Rate for Protocol Cohort

A significant decrease in the protocol cohort infection rate was observed after the implementation of postoperative infection control protocol (surgical dressing measures) in January 2013 and physician awareness in May 2015. The infection rate decreased by 45% from 3.8% to 2.1% (p = 0.03).

Control Cohort Results:

• Baseline (Jan 2007-Feb 2011): 0.7% (47 infections/6643 procedures)
• During preoperative measures period (Mar 2011-Dec 2012): Increased to 1.6% (8 infections/486 procedures)
• During postoperative measures period (Jan 2013-Apr 2015): Decreased to 1.1% (15 infections/1416 procedures)
• During physician awareness period (May 2015-Jul 2016): Further decreased to 0.8% (5 infections/645 procedures)
• Downward trend but not statistically significant (1.6% to 0.8%, p = 0.28)

Figure 3: Spinal Fusion Postoperative SSI Rate for Control Cohort

A downward trend in the control cohort infection rate was observed with the implementation of physician awareness in May 2015, though the reduction from 1.6% to 0.8% was not statistically significant (p = 0.28).

Cost Savings:

The average inpatient hospital cost for treating a postoperative spinal fusion surgery infection was calculated at $19,400 (based on actual patient encounters with the Division of Infectious Diseases).

• Estimated annual cost savings of $97,000 when comparing baseline period to final period with all interventions in place
• Estimated annual cost savings of $291,000 when comparing preoperative measures period to final period with all interventions in place
• These estimates represent direct and semivariable hospital costs only, and are likely underestimates as they do not include outpatient or indirect costs to patients and families

Discussion

Contrary to expectations, preoperative infection prevention measures alone (CHG bathing, nasal screening and decolonization) were not effective in reducing SSI rates, and infection rates actually increased. This may be partly due to low compliance (less than 50%) during the initial period and a steadily rising baseline infection trend.

The most significant improvements came from the combination of postoperative surgical dressing measures and physician awareness. This contrasts with some other studies that found preoperative measures effective in other surgical populations.

Physician awareness was likely effective because it fostered accountability through information sharing. Individual neurosurgeons received data on their personal infection rates and ranking compared to peers, creating transparency and motivation for improvement.

The study results suggest that information sharing and physician engagement as supplements to formal infection control measures lead to improvements in surgical outcomes and cost reduction.

Limitations

• Not a randomized controlled trial; other factors could have influenced the observed results
• No control for potential confounding variables such as case complexity or patient comorbidities over time
• Potential increase in minimally invasive surgeries over time could influence results as these have been associated with lower infection rates
• Use of intraoperative vancomycin powder was not controlled or tracked
• Different baseline infection rates between protocol and control cohorts (3.0% vs 0.7%) suggest potential differences in case complexity, surgical approach, or patient comorbidities
• Cost calculations are estimates and only include inpatient costs, not outpatient or indirect costs

Conclusion

A novel paradigm for spine surgery infection control combined with physician awareness methods resulted in significantly decreased SSI rates and an associated cost reduction. The combination of postoperative surgical dressing measures and individualized physician awareness achieved a 45% reduction in infection rates in the protocol cohort (from 3.8% to 2.1%) and a 54% reduction in overall infection rates (from 3.3% to 1.5%). This resulted in an estimated annual cost savings of $291,000. Information sharing and physician engagement as supplements to formal infection control measures result in improvements in surgical outcomes and costs. These strategies should be incorporated into standard practice for spine surgery.