Assessment of Urinalysis Reflex to Culture Criteria: Impact on Antimicrobial Usage

Objectives: To assess the predictive value of the urinalysis (UA) reflex criteria’s parameters and to evaluate the criteria’s impact on antimicrobial usage\r\nMethods: A prospective study using laboratory data was conducted on inpatient urine samples with orders placed for Urinalysis Reflex Culture (UARC) in a 400-bed acute care hospital. A total of 4016 urine samples were collected and examined between February and April 2020. The UA results were then subjected to the laboratory UA reflex criteria for reflecting UA to culture.  Multivariable logistic regression was utilized in evaluating the effectiveness of the criteria’s parameters to predict positive urine cultures\r\nResults: The total number of the positive UA reflex samples was 1539, which accounted for 38.3% of all the UA samples. Moreover, those positive UA samples were reflexed to urine cultures. Among the urine samples that were cultured, 45.1% (n = 694) were negative urine cultures while 54.9% (n = 845) were positive urine cultures. The UA reflex criterion was associated with positive predictive values for positive urine cultures between 26.30% and 92.96%.\r\nConclusions: The current Laboratory UA reflex criterion is not highly effective in predicting positive urine culture, thus potentially leading to the inappropriate antimicrobial usage.