Risk Factors for Hospital-Based Surgical Site Infections

Background: Surgical site infections (SSIs) contribute to morbidity and are costly to the healthcare system. Objective: To identify factors associated with SSIs. Methods: Case-control study analyzing the Nationwide Readmission Database (NRD). Results: We identified 45,445 SSIs. Infection rates were higher in those who were obese (BMI ≥ 30) (OR: 1.39, 95% CI: 1.28-1.51); tobacco users (OR: 1.08, 95% CI: 1.02-1.15); diagnosed with diabetes (OR: 1.16, 95% CI: 1.10-1.22); with Elixhauser Comorbidity Index ≥2 (OR: 1.14, 95% CI: 1.09-1.20), admitted to hospital for 4-6 days (OR: 1.35, 95% CI: 1.29-1.42); in medium size hospital (OR: 1.15, 95% CI: 1.05-1.26); or large-size hospital (OR: 1.43, 95% CI: 1.31-1.56). In contrast, patients who were 60-79 years old (OR: 0.78, 95% CI: 0.73-0.84); 80 years or older (OR: 0.66, 95% CI: 0.59-0.73); female (OR: 0.95, 95% CI: 0.91-0.99); underweight (BMI < 18.5) (OR: 0.14, 95% CI: 0.03-0.59); in a non-metropolitan hospital (OR: 0.83, 95% CI: 0.75-0.91); self-pay (OR: 0.82, 95% CI: 0.74-0.91); or covered by Medicare (OR: 0.86, 95% CI: 0.80-0.91) had lower odds. Limitations: Initial data entry to NRD is susceptible to human error. Conclusions: Patients who are obese, use tobacco, have multiple comorbidities, and have long hospital stays in medium-to-large size hospitals are at risk of SSIs. Conversely, odds of SSIs are lower in females, age ≥ 60, BMI < 18.5, self-pay or Medicare (versus private insurance), or at smaller hospitals. Understanding factors associated with SSIs may help surgeons anticipate complications.