Excess cost associated with primary hip and knee joint arthroplasty surgical site infections: a driver to support investment in quality improvement strategies to reduce infection rates.

AIM: To determine the excess costs attributable to surgical site infections (SSI) following primary hip and knee joint arthroplasty at Auckland City Hospital.

METHODS: A retrospective case-control study. Cases were patients who developed a SSI following primary hip (THA) and knee arthroplasty (TKA) surgery within 90 days of the procedure. Cases were matched 1:2 with controls; patients whose primary hip and knee arthroplasty procedures were not complicated by infection. Controls were matched for age, gender, date of surgery, type of surgery, and ASA category. The length of stay (LOS) and hospital costs for the initial admission and subsequent readmission for infection were calculated from the clinical costing system at Auckland District Health Board.

RESULTS: Eleven cases were identified; 3 following TKA, 7 following THA, and 1 following hemiarthroplasty of the hip. Infections were classified as superficial, 1, joint space, 1, and deep incisional, 9. Five SSI were identified during the initial admission for joint arthroplasty and 6 patients were readmitted with an SSI. Compared to the control patients, SSIs were associated with an excess mean cost of $40,121 and an excess mean LOS of 42 days.

CONCLUSIONS: There is a significant increase in LOS and cost associated with SSI following primary THA and TKA at Auckland City Hospital. In addition to the excess cost associated with SSI, there are also opportunity costs resulting from their impact on elective surgical waiting lists. This reinforces the significant positive economic impact a successful strategy to reduce SSIs associated with primary joint arthroplasty procedures will have.