Invasiveness Index as a Risk Factor for Deep Surgical Site Infection after Fusion, Refusion and Laminectomy
Background: Invasiveness index (II), which is determined by surgical approach, procedure, and number of spine levels treated, has been independently associated with surgical site infection (SSI) risk in patients undergoing elective spine surgery. The use of this measure has not been evaluated in previous risk assessment models for SSI using National Health Safety Network (NHSN) definitions including all fusion (FUSN), refusion (RFUSN) and laminectomy (LAM) procedures. We performed a retrospective cohort study to determine potential SSI risk factors in patients undergoing NHSN spine surgery procedures.
Methods: Patients undergoing FUSN, RFUSN, LAM procedures at our institution from 2007-13 were identified by Infection Control using NHSN definitions as part of routine surveillance. Variables were abstracted from electronic hospital databases (Admission- Discharge-Transfer, Microbiology, Pharmacy, Infection Control) and validated with manual chart review. To assess potential risk factors for deep or organ/space (O/S) SSI, univariate analyses were performed using Chi-square for binary variables and logistic regression for continuous or categorical variables.
Results: Among 6600 patients, 46 deep infections (0.69/100 procedures) and 16 O/S infections (0.24/100 procedures) were identified. Of the 4353 patients with complete data for calculation of II, there were 2624 (60%) FUSN, 1490 (34%) LAM, and 239 (6%) RFUSN. On univariate analyses, higher II, age > 65, ASA score ≥ 4, prior spine surgery, duration of surgery and trauma were significantly associated with SSI (Table 1).
Conclusion: II may be associated with SSI in patients undergoing FUSN, RFUSN, and LAM for elective and non-elective indications. Further study is needed to determine if II will enhance prediction of SSI risk when classified using NHSN definitions.
B. L. Hollenbeck,
A. P. White, None
D. S. Yassa, None
S. B. Wright, None