Urine particles analysis: Performance evaluation of Sysmex UF-1000i and comparison among urine flow cytometer, dipstick, and visual microscopic examination

Abstract

Introduction. Our objective was to evaluate a newly invented urine flow cytometer, and select an optimal strategy for urinalysis in clinical practice. Methods. The performance of UF-1000i was evaluated in both control material and patient samples. A total of 1631 specimens were collected and analysed by visual microscopy examination (VME), UF-1000i flow cytometer (Sysmex Medical Electronics Co, Kobe, Japan) and an automated dipstick reflectometer Clinitek Atlas (Bayer Corp, Elkhart, USA). Results. UF-1000i showed good imprecision performance for the main parameters in urine particles with CV values less than 20%. The results from UF-1000i correlated well with VME for erythrocytes (r = 0.96), leukocytes (r = 0.98), and epithelial cell (r = 0.84). The area under the receiver operating curve (AUC) was 0.879, 0.903, 0.783, and 0.817 respectively for erythrocytes, leukocytes, bacteria and CAST in UF-1000i. While in Clinitek Atlas, the AUC was 0.848, 0.803, 0.761, and 0.754 respectively. Sensitivity of combination of the two methods for screening remained at 98% as compared to VME alone, while reducing the visual review rate down to 40%. Conclusion. UF-1000i is capable of reproducible measurement of urine particles in the clinically relevant range and shows its advantage over Atlas. Combination of the two methods is an optimal strategy for urine sample screening.

Key Words::

• Urinalysis
• urine flow cytometer
• reflectometer
• urine particle analysis
• performance evaluation

Acknowledgement

We would like to express our thanks to Ms Hui Wang (Sysmex Corporation, Guangzhou) and all the staff in our department for their kind help. Special thanks to the volunteers who participated in this study.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.