Presentation Number 4-042 Total Burden Assessment of Surgical Site Infections in Initial Admissions and Readmissions Using National Administrative Claims Data

Background/Objectives: Surgical site infections (SSIs) have a significant negative impact on hospital reimbursement and clinical outcomes. This study quantifies the incidence and economic burden of SSIs in 6 selected surgical categories as an aggregate. Uniquely, this investigation focuses on the impact of patients having SSI in their initial admission with downstream outcomes, including readmission counts, payments and total length of stay (LOS) to assess the complete consequences of SSI, not just a single episode of care. Methods: Patients were drawn from the Thomson Medstat Marketscan Database, a national administrative database that longitudinally tracks commercial claims data from nearly 150 million patients since 1995. The economic impact of SSI was evaluated in selected 6 high-volume surgery specialties specified by ICD9-CM procedure code (cardiac, general, orthopedic, neurological, plastic and ob-gyn) during the period January 2007 to December 2009. Patients qualified if they had no prior surgeries in a 90-day look back period. Subsequently, each patient was observed for readmissions in a 90-day look forward period. Patients developing infections during their index admission were defined by ICD-9-CM codes 998.5x, 998.66 and 998.67 as their secondary diagnosis; patients developing one or more SSI's during their readmissions were defined by the same codes identified as their primary readmission diagnoses. The total burden of SSI was assessed by evaluating differences in LOS and provider payments relative to patients with no SSI: 1) during the initial admission for patients experiencing SSI; (2) during the 90-day post surgery for patients who had developed SSI in their initial admission; and 3) in patients developing SSI in their 90-day post-operative period. Generalized Linear Models adjusting for patient age, gender, region and diabetes were used to compute mean differences and 95% confidence intervals. A constant sample based on the index procedure census was used for all three analyses to maintain a consistent denominator. Results: Patients developing SSI as a complication of index surgery incur an additional LOS of 6.86 days (95% CI: 6.71-7.02 days) and $20,288 (95% CI: $19,369-$21,206) of extra payments. Patients during the 90-day post surgery period who had developed SSI in their initial admission are likely to have 0.21 more downstream readmissions (95% CI: 0.19-0.21), 1.94 days additional LOS (95% CI: 1.81-2.08) and $5,549 additional payments (95% CI: $5,106-$5,993). Patients developing SSI at any time during their 90-day postoperative period are at risk of 1.3 additional readmissions, and incur an average additional LOS of 8.37 days (95% CI: 8.26-8.47) and $25,436 (95% CI: $25,094-$25,779) in additional payments. Conclusions: SSI increases current and downstream burdens by a factor of 3 to 10 times in terms of readmission rates, and additional length of stay and payments. Appreciation of its impact emphasizes the importance of control and prevention of this surgical complication.