comparison of the automated cobas u 701 urine microscopy and UF-1000i flow cytometry systems and manual microscopy in the examination of urine sediments

Abstract

Background: The cobas u 701, a new au- tomated image-based urine sediment ana- lyzer, was introduced recently. In this study, we compared its performance with that of UF-1000i flow cytometry and manual mi- croscopy in the examination of urine sed- iments. Methods: Precision, linearity, and carry-over were determined for the two urine sediment analyzers. For a comparison of the method, 300 urine samples were ex- amined by the automated analyzers and by manual microscopy using a KOVA chamber. Results: Within-run coefficients of variation (CVs) for the control materials were 7.0– 8.8% and 1.7–5.7% for the cobas u 701 and UF-1000i systems, respectively. Between- run CVs were 8.5–9.8% and 2.7–5.4%, re-spectively. Both instruments showed good linearity and negligible carry-over. For red blood cells (RBC), white blood cells (WBC), and epithelial cells (EPI), the overall concor- dance rates within one grade of difference among the three methods were good (78.6– 86.0%, 88.7–93.8%, and 81.3–90.7%, re- spectively). The concordance rate for casts was poor (66.5–68.9%). Conclusion: Com- pared with manual microscopy, the two au- tomated sediment analyzers tested in this study showed satisfactory analytical perfor- mances for RBC, WBC, and EPI. However, for other urine sediment particles confirma- tion by visual microscopy is still required.