Objective: To assess risk factors for SSI after abdominal hysterectomy (AH).
Methods: We conducted a retrospective case-control study of 271 (91 cases and 180 controls) patients who underwent AH from 1/3/07 to 4/15/09. A case was any patient who met the Centers for Disease Control and Prevention’s definition of SSI or who had incisional cellulitis within 30 days after the procedure. Controls were randomly selected from patients who had undergone AH but did not meet the definition of SSI. Any patients selected as controls that met the definition of SSI (primarily patients with cellulitis) were included as cases and replaced by new controls. Demographic data and data on underlying diseases, medications, operations, hospital stays, and post-operative visits were abstracted from the medical records. Multivariable analysis (MA) was conducted using stepwise logistic regression. Data were analyzed using SAS.
Results: Of the SSIs, 26 (28.6%) were deep/organ space infections, 18 (19.8%) were superficial incisional infections without cellulitis, and 47 (51.6%) were superficial incisional cellulitis. Signs and symptoms of SSI included erythema (70.3%), fever (61.5%), and pain/tenderness (45.1%). The mean age was 55 years (range: 23-84). The mean BMI for cases (38.8) was higher than for controls (32.7; P < 0.0001). Cases and controls were similar with respect to: diabetes, smoking, preoperative chlorhexidine showers, procedure durations, and post-op hemoglobin values. Preoperative variables that were independent predictors of SSI were: BMI (P = 0.0003, odds ratio [OR] = 1.1; 95% confidence interval [95%CI] 1.0, 1.1), admission diagnosis of uterine cancer (P = 0.005; OR = 2.4; 95%CI 1.3, 4.6), asthma (P < 0.0001; OR = 6.9; 95%CI 2.6, 18.3), drug abuse history (P = 0.01; OR = 16.9; 95%CI 1.8, 159.4), and mild pulmonary disease (P = 0.02; OR = 14.4; 95%CI 1.5, 136.9). When seroma and hematoma were included in the intraoperative and postoperative MA, seroma was the only independent risk factor (P < 0.0001; OR = 6.8; 95%CI 3.0, 15.4). When seroma and hematoma were excluded, independent risk factors were: total vs. radical hysterectomy (P = 0.002; OR = 4.8; 95%CI 1.8, 13.3), clindamycin for prophylaxsis (P = 0.02; OR = 3.5; 95%CI 1.3, 9.5), and a NNIS risk index ≥ 2 (P = 0.05; OR = 1.8; 95%CI 1.0, 3.2). SSIs were associated with more days of antimicrobial treatment postoperatively (P = 0.004; OR = 1.2; 95%CI 1.0, 1.3) and readmission
Conclusions: Elevated BMI, asthma, drug abuse, and hysterectomy as treatment for uterine cancer, were the preoperative factors independently associated with SSI. Receiving clindamycin rather than a cephalosporin perioperatively might increase the risk of SSI. Surgical techniques that prevent seroma might decrease the incidence of SSI. SSIs increased utilization of healthcare significantly.