Risk factors and associated complications for postoperative urinary retention after lumbar surgery for lumbar spinal stenosis.

Background Context: Postoperative urinary retention (POUR) is a very common postoperative complication of all surgeries (5%-70%) that may lead to complications such as urinary tract infection (UTI), bladder overdistension, autonomic dysregulation, and increased postoperative length of stay (LOS). Within the field of spine surgery, the reported incidence rate of POUR is highly variable (5.6%-38%). Lack of clear stratification of surgical level, spinal pathology, and inadequate sample size are major limitations of available studies concerning POUR following spine surgery, which may lead to inconsistency in the incidence of POUR and the ability to model its occurrence and consequences.

Purpose: This study examines the incidence, predictive factors, and complications of POUR in patients undergoing elective posterior lumbar decompression with or without fusion for lumbar stenosis to eliminate bias from studying procedures done in different anatomical regions and with different approaches. Additionally, this study intends to identify the consequences of POUR.

Study Design And Setting: A retrospective consecutive cohort analysis was performed to examine patients undergoing posterior lumbar decompression who did and did not develop POUR.

Patient Sample: All patients undergoing posterior lumbar decompression with or without fusion for lumbar stenosis with claudication from January 2014 through December 2015 at our institution were evaluated. Patients under the age of 18 and patients with spinal malignancies or infections were excluded.

Outcome Measures: Physiological measures included identification of POUR by evidence of reinsertion of a Foley catheter, use of straight catheterization postoperatively, or by a clear medical diagnosis with pharmacologic treatment. Other physiological measures included identification of development of UTI, sepsis, acute kidney injury (AKI), surgical site infection (SSI), or readmission within 90 days after surgery, as well as LOS and discharge disposition.

Methods: The electronic medical record was searched for all patients meeting inclusion and exclusion criteria. Postoperative urinary retention was defined as reinsertion of a Foley catheter, use of straight catheterization postoperatively, or a clear medical diagnosis with pharmacologic treatment. Statistical analysis was performed in R statistical software package version 3.3.2. Multiple variable selection techniques were used to determine appropriate variables for regression models, and logistic models were fit to the development of POUR and postoperative complications, whereas a linear regression model was used for LOS.

Results: Data were collected on 1,592 consecutive patients. Among the sample population, the mean age at surgery was 67 (standard deviation 10.1) and 45% of patients were women. The incidence rate of POUR was 17.1% (273/1592). Increased age (odds ratio [OR]=1.04; 95% confidence interval [CI], 1.02-1.06; p<.001), benign prostatic hyperplasia (BPH) (OR=1.92; 95% CI, 1.32-2.78); p<.001), previous AKI (OR=3.29; 95% CI, 1.11-9.29; p=.025), and previous UTI (OR=1.69; 95% CI, 1.24-2.24; p<.001) significantly increased the probability of developing POUR. Factors including increased body mass index, coronary artery disease, congestive heart failure, diabetes mellitus, chronic obstructive pulmonary disease, tobacco use, and fusion were found to be non-significant and were excluded from the model. With respect to complications, POUR was found to be associated with development of UTI (OR=4.50; 95% CI, 3.14-6.45; p<.001), sepsis (OR=4.05; 95% CI, 1.16-13.55; p=.022), increased LOS (p<.001), increased likelihood to be discharged to a skilled nursing facility (SNF) (OR of discharge to home=0.44; 95% CI, 0.32-0.62; p<.001), and increased risk of readmission within 90 days of the index surgery (OR=1.60; 95% CI, 1.11-2.26; p=.009). Development of POUR did not increase the risk of developing AKI (OR=2.45; 95% CI, 0.93-6.30; p=.063) or a SSI (OR=1.09; 95% CI, 0.56-2.02; p=.79).

Conclusions: Overall, POUR was a significant risk factor for the development of UTI, sepsis, increased LOS, discharge to a SNF, and readmission within 90 days. Surgeons and anesthesiologists should take preventative measures against POUR in individuals with increased age, BPH, AKI, and UTI within 90 days before surgery, as these factors were found to significantly increase the risk of POUR.