The Impact of Surgical Site Infection on Patient Outcomes After Open Posterior Instrumented Thoracolumbar Surgery for Degenerative Disorders

BACKGROUND: Few reports in the literature have described the long-term outcome of postoperative infection from the patient perspective. The aim of the present study was to determine if complicated surgical site infection (SSI) affects functional recovery and surgical outcomes up to 2 years after posterior instrumented thoracolumbar surgery for the treatment of degenerative disorders. METHODS: This retrospective cohort study involved patients who had been enrolled in a previous randomized controlled trial that examined antibiotic use for open posterior multilevel thoracolumbar or lumbar instrumented fusion procedures. In the present study, patients who had SSI (n = 79) were compared with those who did not (n = 456). Patient-reported outcome measures (PROMs) included the Oswestry Disability Index (ODI), leg and back pain scores on a numeric rating scale, Short Form-12 (SF-12) summary scores, and satisfaction with treatment at 1.5, 3, 6, 12, and 24 months. Surgical outcomes included adverse events, readmissions, and additional surgery. RESULTS: The median time to infection was 15 days. Of the 535 patients, 31 (5.8%) had complicated infections and 48 (9.0%) had superficial infections. Patients with an infection had a higher body mass index (BMI) (p = 0.001), had more commonly received preoperative vancomycin (p = 0.050), were more likely to have had a revision as the index procedure (p = 0.004), had worse preoperative mental functioning (mental component summary score, 40.7 ± 1.6 versus 44.1 ± 0.6), had more operatively treated levels (p = 0.024), and had a higher rate of additional surgery (p = 0.001). At 6 months after surgery, patients who developed an infection scored worse on the ODI by 5.3 points (95% confidence interval [CI], 0.4 to 10.1 points) and had worse physical functioning by -4.0 points (95% CI, -6.8 to -1.2 points). Comparison between the groups at 1 and 2 years showed no difference in functional outcomes, satisfaction with treatment, or the likelihood of achieving the minimum clinically important difference (MCID) for the ODI. CONCLUSIONS: SSI more than doubled the post-discharge emergency room visit and additional surgery rates. Patients with SSI initially (6 months) had poorer overall physical function representing the delay to recovery; however, the negative impact resolved by the first postoperative year. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.