Reflex urine culture testing in an ambulatory urology clinic: Implications for antibiotic stewardship in urology

OBJECTIVES

To evaluate the performance characteristics of urinalysis and urine microscopy parameters for predicting urine culture results and to implement a reflex urine culture program.

METHODS

We reviewed the charts of all patients presenting to our clinic January-March 2013 and June-August 2014, excluding those who were catheter-dependent or with urinary diversions. We assessed the association of urinalysis and urine microscopy parameters on urine culture outcomes defining a positive urinalysis as nitrite-positive and/or the presence of ≥5 white blood cells per high-powered field with bacteria and a positive urine culture as ≥10 000 colony-forming units/mL excluding diphtheroids. We carried out logistic regression to assess for predictors of positive urine culture to inform implementation of a reflex urine culture program.

RESULTS

A total of 2764 patients were evaluated. Logistic regression using urinalysis variables identified positive nitrites (odds ratio 18.6, P < 0.001) and large leukocyte esterase (odds ratio 41.8, P < 0.001) as the strongest predictors of positive urine culture. Logistic regression using urine microscopy variables identified >50 white blood cells per high-powered field (odds ratio 13.6, P < 0.001) and moderate/many bacteria (odds ratio 16.8, P < 0.001) as the strongest predictors of positive urine culture. We used our positive urinalysis definition to implement the reflex urine culture program and noted a 60% reduction in urine culture rates over the first 3 months of implementation.

CONCLUSIONS

A urine positive for nitrites and/or ≥50 white blood cells per high powered field with bacteria seems to have a strong association with a positive urine culture and the best negative predictive value. A reflex urine culture program is an effective strategy to decrease the rates of unnecessary urine culture and their associated costs.

Utility of routine urinalysis and urine culture testing in an ambulatory urology clinic: a quality improvement initiative in a Veterans healthcare facility

INTRODUCTION

Urinalysis (UA) and urine culture (UCx) are commonly performed tests in the urology clinic. Many of these urine studies are performed prior to the patient visit may not always be indicated, thus contributing to unintended consequences such as antibiotic use and costs without enhancing patient care. Our objective was to perform a quality improvement initiative aimed to assess the utility of routine UA/UCx.

MATERIALS AND METHODS

The practice pattern at our site's Veteran Affairs (VA) urology clinic prior to 2014 was to obtain routine UA/UCx on most clinic visits prior to patient evaluation. Starting in 2014, we designed an intervention whereby our nurse practitioner triaged all new patient referrals and selectively ordered UA/UCx. We performed multivariable logistic regression to assess for predictors of obtaining UA or UCx.

RESULTS

A total of 1308 patients were seen in January-March 2013 and 1456 in June-August 2014 and were included in this analysis. Fewer patients in 2014 received UA (59.8% versus 70.0%, p < 0.001) and UCx (49.6% versus 64.2%, p < 0.001). There was a decreased odds of obtaining UA in 2014 (OR 0.52, p < 0.001) as well as a decreased odds of obtaining UCx in 2014 (OR0.38, p < 0.001) on multivariable logistic regression. The results of UA/UCx only rarely resulted in change of management in either cohort (3%). Selective ordering resulted in an estimated cost savings of $4915.08/month in UCx costs alone.

CONCLUSIONS

Our quality improvement initiatives reduced rates of UA/UCx testing when providers assess patients prior to ordering these tests. The implication of this initiative is significant cost savings for the healthcare system.