Date of Award

January 2022

Document Type


Degree Name

Medical Doctor (MD)



First Advisor

Joseph T. King, Jr.

Second Advisor

Angeliki Louvi


Urinary tract infections (UTIs) are the most common bacterial infection in the United States, placing significant demands on our healthcare system already constrained by rising costs and limited resources. While patient complications occur in all areas of surgery, the issue around neurosurgical patients deserves special attention as treatment of surgical site infections in neurosurgery is the most expensive among all surgical specialties. Complication rates are also disproportionately higher in patients over 65 years old, which are noteworthy in caring for our aging patient population.

While the adverse effects of a post-operative UTI have been well described in the surgical literature, there has been much less work studying the impact of a pre-operative UTI on surgical morbidity and mortality. The work presented within this thesis utilizes the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP), a nationally validated, risk-adjusted database, to compare post-operative infection rates and 30-day outcomes among neurosurgical patients with and without a pre-operative UTI. Spine and cranial surgery patients were analyzed as two separate cohorts as these surgeries have different risk factors and characteristics. My primary outcome was any postoperative infection (pneumonia, sepsis, surgical site infection, and organ space infection). Secondary outcomes included surgical site infections, non-infectious complications, return to operating room, and 30-day readmission and mortality. I created univariable, then multivariable Poisson regression models accounting for demographics, comorbidities, laboratory values, and procedure details to study these associations. Additionally, multiple imputation was used to account for missing data in the data set.

In both spine and cranial surgical patient cohorts, patients with a pre-operative UTI were more likely to be older, female, emergency cases, with a higher American Society of Anesthesiologists (ASA) score, and more medical comorbidities (for all, P<0.001). Spine surgery patients with a pre-operative UTI had higher rates of infectious and non-infectious complications, return to operating room, and unplanned readmissions (for all, P<0.001). Even after controlling for demographics, comorbidities, laboratory values, and case details, preoperative UTI status was significantly associated with more postoperative infectious complications (incidence rate ratio [IRR]: 2.88, 95% confidence interval [CI]: 2.25-3.70, P<0.001). Similarly in a cohort of cranial surgeries, patients with a pre-operative UTI were also at higher risk for post-operative infections, non-infectious complications, non-home discharges, and longer hospital stays (for all, P<0.05). However, there were no statistically significant differences in mortality rates (spine IRR: 0.70, 95% CI: 0.17–2.83; P=0.618; cranial IRR: 0.72, 95% CI: 0.32-1.61; P=0.427).

Infection control is a pressing issue for both surgeons and patients. Results of this thesis demonstrate that pre-operative UTI status is significantly associated with post-operative infections and worse 30-day outcomes. The findings suggest that neurosurgeons should consider delaying or cancelling surgery in patients with a UTI in elective situations to reduce adverse outcomes.


This thesis is restricted to Yale network users only. It will be made publicly available on 06/29/2024