Development of a Single Model to Predict Surgical Site Infection and Non-Infectious Wound Complications after Mastectomy with Immediate Reconstruction

Background: Surgical site infections (SSIs) and non-infectious wound complications (NIWCs) after mastectomy with immediate reconstruction can delay adjuvant treatment and result in poorer cosmesis of the breast reconstruction. Our objective was to determine if a single model can reliably predict both SSIs and NIWCs after mastectomy with immediate reconstruction.

Methods: We established a cohort of women < 65 years of age with mastectomy and breast reconstruction from 1/1/2004–12/31/2011 using commercial claims data. ICD-9-CM diagnosis codes were used to identify NIWCs (i.e., tissue necrosis, dehiscence, and/or fat necrosis) and SSIs within 180 days after surgery. Logistic regression was used to create individual risk models for SSI and NIWCs, and a third model with the composite outcome SSI or NIWC.

Results: Of 7,086 procedures, 738 (10.4%) were complicated by SSI, and 685 (9.7%) were complicated by an NIWC. Independent risk factors retained in both the SSI and NIWC models included diabetes, hypertension, obesity, psychoses, smoking-related diseases, bilateral mastectomy, and type of breast reconstruction. The final model for the composite outcome SSI/ NIWC included these risk factors plus coagulopathy, depression, liver disease, and tobacco use disorder. The composite model performed better than the SSI model (c-statistic 0.626 vs. 0.604, respectively), but did not perform as well as the NIWC model (c-statistic 0.661). Of the 738 women with SSI, 441 (60%) were classified as high risk (> 15%) using the composite model, while 465/685 (68%) of women with NIWC were classified as high risk of wound complication with the composite model.

Conclusion: A composite SSI/NIWC model can be used to predict women at higher risk of SSI and NIWC. Given the overlap in risk factors for SSI and NIWC, this model could be helpful for preoperative counseling of women considering immediate reconstruction concerning their risk of postoperative wound complications.