Purpose: The aim of this study was to determine the risk of surgical site infection (SSI) after primary breast-conserving surgery (BCS) versus re-excision among women with carcinoma in situ or invasive breast cancer.
Methods: We established a retrospective cohort of women aged 18-64 years with International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure or Current Procedural Terminology, 4th edition (CPT-4) codes for BCS from 29 June 2004 to 31 December 2010. Prior insurance plan enrollment of at least 180 days was required to establish the index BCS; subsequent re-excisions within 180 days were identified. SSIs occurring 2-90 days after BCS were identified by ICD-9-CM diagnosis codes. The attributable surgery was defined based on SSI onset compared with the BCS date(s). A χ (2) test and generalized estimating equations model were used to compare the incidence of SSI after index and re-excision BCS procedures.
Results: Overall, 23,001 women with 28,827 BCSs were identified; 23.2 % of women had more than one BCS. The incidence of SSI was 1.82 % (418/23,001) for the index BCS and 2.44 % (142/5,826) for re-excision BCS (p = 0.002). The risk of SSI after re-excision remained significantly higher after accounting for multiple procedures within a woman (odds ratio 1.34, 95 % confidence interval 1.07-1.68).
Conclusions: Surgeons need to be aware of the increased risk of SSI after re-excision BCS compared with the initial procedure. Our results suggest that risk adjustment of SSI rates for re-excision would allow for better comparison of BCS SSI rates between institutions.