Study design:

Retrospective review of prospectively collected data.

Objective:

The aim of this study was to investigate risk factors associated with the timing of urinary tract infection (UTI) after elective spine surgery, and to determine whether postoperative UTI timing affects short-term outcomes.

Summary of background data:

Urinary tract infection (UTI) is a common post-surgical complication; however, the predominant timing, location, and potential differential effects have not been carefully studied.

Methods:

We analyzed elective spine surgery patients from 2012 to 2018 in the ACS National Surgical Quality Improvement Program (NSQIP). We grouped patients with postoperative UTI by day of onset relative to discharge, to create cohorts of patients who developed inpatient UTI and post-discharge UTI. We compared both UTI cohorts with a control (no UTI) population and with each other to identify differences in baseline characteristics including demographic, comorbidity and operative factors. We performed multivariate logistic regression to identify predictors of UTI in each cohort and to assess adjusted risks of poor outcomes associated with UTI timing.

Results:

A total of 289,121 patients met inclusion criteria and 0.88% developed UTI (n = 2553). Only 31.6% of UTIs occurred before discharge (n = 806), with 68.4% occurring after discharge (n = 1747). The inpatient UTI cohort had significantly longer operative time, more fusion procedures, more posterior procedures, and more procedures involving the lumbar levels than the post-discharge cohort. Predictors of inpatient UTI included procedure type, spine region, and approach. Predictors of post-discharge UTI included length-of-stay and discharge destination. Both UTI cohorts were significantly associated with sepsis; however, post-discharge UTI carried a higher odds (adjusted odds ratio [aOR] = 24.90, 95% confidence interval [CI] = 21.05-29.45, P < 0.001 vs. aOR = 14.31, 95% CI = 11.09-18.45, P < 0.001). Inpatient UTI was not associated with 30-day readmission, although post-discharge UTI was (aOR = 8.23, 95% CI = 7.36-9.20, P < 0.001). Conversely, inpatient UTI was associated with increased odds of 30-day mortality (aOR = 3.23, 95% CI = 1.62-6.41, P = 0.001), but post-discharge UTI was not.

Conclusion:

Predictive factors and outcomes differ based on timing of UTI after elective spine surgery. Before discharge, procedure -specific details predict UTI, but after discharge they do not. These findings suggest that traditional thinking about UTI prevention may need modification.Level of Evidence: 3.