Nicholas M Mohr1,2, Karisa K Harland1, Victoria Crabb3, Rachel Mutnick1, David Baumgartner1, Stephanie Spinosi1, Michael Haarstad1, Azeemuddin Ahmed1, Marin Schweizer4,5, Brett Faine1,6. 1. Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, IA. 2. Division of Critical Care, Department of Anesthesia, University of Iowa Carver College of Medicine, Iowa City, IA. 3. Department of Epidemiology, University of Iowa College of Public Health, Iowa City, IA. 4. Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA. 5. Iowa City Veterans Administration Health Care System, Iowa City, IA. 6. Department of Pharmaceutical Care, University of Iowa Hospitals and Clinics, Iowa City, IA.
Abstract
OBJECTIVES: The presence of squamous epithelial cells (SECs) has been advocated to identify urinary contamination despite a paucity of evidence supporting this practice. We sought to determine the value of using quantitative SECs as a predictor of urinalysis contamination. METHODS: Retrospective cross-sectional study of adults (≥18 years old) presenting to a tertiary academic medical center who had urinalysis with microscopy and urine culture performed. Patients with missing or implausible demographic data were excluded (2.5% of total sample). The primary analysis aimed to determine an SEC threshold that predicted urine culture contamination using receiver operating characteristics (ROC) curve analysis. The a priori secondary analysis explored how demographic variables (age, sex, body mass index) may modify the SEC test performance and whether SECs impacted traditional urinalysis indicators of bacteriuria. RESULTS: A total of 19,328 records were included. ROC curve analysis demonstrated that SEC count was a poor predictor of urine culture contamination (area under the ROC curve = 0.680, 95% confidence interval [CI] = 0.671 to 0.689). In secondary analysis, the positive likelihood ratio (LR+) of predicting bacteriuria via urinalysis among noncontaminated specimens was 4.98 (95% CI = 4.59 to 5.40) in the absence of SECs, but the LR+ fell to 2.35 (95% CI = 2.17 to 2.54) for samples with more than 8 SECs/low-powered field (lpf). In an independent validation cohort, urinalysis samples with fewer than 8 SECs/lpf predicted bacteriuria better (sensitivity = 75%, specificity = 84%) than samples with more than 8 SECs/lpf (sensitivity = 86%, specificity = 70%; diagnostic odds ratio = 17.5 [14.9 to 20.7] vs. 8.7 [7.3 to 10.5]). CONCLUSIONS: Squamous epithelial cells are a poor predictor of urine culture contamination, but may predict poor predictive performance of traditional urinalysis measures.
OBJECTIVES: The presence of squamous epithelial cells (SECs) has been advocated to identify urinary contamination despite a paucity of evidence supporting this practice. We sought to determine the value of using quantitative SECs as a predictor of urinalysis contamination. METHODS: Retrospective cross-sectional study of adults (≥18 years old) presenting to a tertiary academic medical center who had urinalysis with microscopy and urine culture performed. Patients with missing or implausible demographic data were excluded (2.5% of total sample). The primary analysis aimed to determine an SEC threshold that predicted urine culture contamination using receiver operating characteristics (ROC) curve analysis. The a priori secondary analysis explored how demographic variables (age, sex, body mass index) may modify the SEC test performance and whether SECs impacted traditional urinalysis indicators of bacteriuria. RESULTS: A total of 19,328 records were included. ROC curve analysis demonstrated that SEC count was a poor predictor of urine culture contamination (area under the ROC curve = 0.680, 95% confidence interval [CI] = 0.671 to 0.689). In secondary analysis, the positive likelihood ratio (LR+) of predicting bacteriuria via urinalysis among noncontaminated specimens was 4.98 (95% CI = 4.59 to 5.40) in the absence of SECs, but the LR+ fell to 2.35 (95% CI = 2.17 to 2.54) for samples with more than 8 SECs/low-powered field (lpf). In an independent validation cohort, urinalysis samples with fewer than 8 SECs/lpf predicted bacteriuria better (sensitivity = 75%, specificity = 84%) than samples with more than 8 SECs/lpf (sensitivity = 86%, specificity = 70%; diagnostic odds ratio = 17.5 [14.9 to 20.7] vs. 8.7 [7.3 to 10.5]). CONCLUSIONS: Squamous epithelial cells are a poor predictor of urine culture contamination, but may predict poor predictive performance of traditional urinalysis measures.
Authors: J Graessler; C S Mehnert; K-M Schulte; S Bergmann; S Strauss; T D Bornstein; J Licinio; M-L Wong; A L Birkenfeld; S R Bornstein Journal: Pharmacogenomics J Date: 2017-06-13 Impact factor: 3.550
Authors: Martin Müller; Nadine Sägesser; Peter M Keller; Spyridon Arampatzis; Benedict Steffens; Simone Ehrhard; Alexander B Leichtle Journal: Diagnostics (Basel) Date: 2022-04-16
Authors: Martin Müller; Ruth Seidenberg; Sabine K Schuh; Aristomenis K Exadaktylos; Clyde B Schechter; Alexander B Leichtle; Wolf E Hautz Journal: PLoS One Date: 2018-02-23 Impact factor: 3.240