Method for reducing false positive rate of leukocyte detected by UF-5000 urine formed component analyzer

Abstract

The invention provides a method for reducing the false positive rate of leukocytes detected by a UF-5000 urine formed component analyzer, and belongs to the field of optimization of detection methods. Aiming at the problem that the false positive rate of leukocytes is high when an existing urine analyzer detects a sample with increased epithelial cells, the invention provides a solution for effectively reducing the false positive rate, and after an optimal CR (WBC)-CW-FSC-P gain value is set, the sample with an epithelial cell interference leukocyte signal is detected. Through the method, the false positive rate of leukocytes can be remarkably reduced, so that misdiagnosis of urinary tract infection caused by the false positive rate is reduced, the accuracy of a urine analyzer is improved, and especially in pregnant women, the misdiagnosis rate can be effectively reduced, the diagnosis efficiency is improved, and unnecessary antibiotic use is reduced. The method is simple to operate, and the clinical application value of the urine analyzer can be improved.

Description

Technical Field

[0001] The invention relates to the field of optimization of urine formed component analyzer detection methods, and in particular to a method for reducing the interference of urine epithelial cells on leukocyte signals and reducing the leukocyte false positive rate. Background Art

[0002] The UF-5000 urine formed component analyzer is a fully automatic urine sediment analyzer newly launched by Sysmex. It can provide quantitative information such as white blood cells, red blood cells, and casts, and can be used for screening and differential diagnosis of urinary tract and kidney diseases, and guide clinical medication. The UF-5000 uses the principle of flow cytometry + nucleic acid fluorescence staining. It irradiates cells and other formed components in urine samples with lasers to measure the scattered light and fluorescence signals generated. The instrument converts the detected scattered light and fluorescence signals into electrical signals, and analyzes and identifies them through software. By comprehensively analyzing various signal parameters (such as light intensity, fluorescence intensity, and scattered light intensity, etc.), it identifies and quantifies different formed components in urine. Due to the characteristics of high accuracy, high speed, and multi-parameter analysis, the UF-5000 urine formed component analyzer is currently widely used in clinical testing.

[0003] Although the UF-5000 instrument has high accuracy, false positive or false negative results that cannot be ignored may still occur in the presence of certain interfering factors. In order to explore the interference of epitheliocytosis on white blood cell counts, we collected urine specimens from patients who met the inclusion and exclusion criteria and visited the outpatient clinic from January 2024 to June 2024, used UF-5000 to detect urine formed elements, and used microscopic counting as the gold standard. After statistical analysis, it was found that UF-5000 had a large number of false positives for white blood cells in the detection of specimens with epitheliocytosis. Specifically, UF-5000 produced 141 false positives for white blood cells in the detection of 575 samples with epitheliocytosis (epithelial cell count>12 / μl), with a false positive rate of 32.12%. Moreover, in 141 samples with false positive results of white blood cells, the white blood cell count results detected by UF-5000 were significantly positively correlated with the epithelial cell count under the microscope (r=0.83, p<0.0001). This shows that when using UF-5000 to detect urine formed elements, the increase in epithelial cells can interfere with the white blood cell detection signal, resulting in an increase in false positive white blood cells, which can lead to adverse consequences such as misdiagnosis of infectious diseases and excessive use of antibiotics. In order to minimize the occurrence of adverse situations such as misdiagnosis, it is generally appropriate to control the false positive rate of white blood cells below 10% in urine formed element detection.

[0004] The compensated forward scatter (CW-FSC-P) gain value (i.e., CR(WBC)-CW-FSC-P gain value) within the white blood cell coefficient ratio (CR) in the UF-5000 detection parameters refers to the compensation of the forward scattered light (FSC) signal through electronic signal processing to eliminate the interference of other cells (such as red blood cells and epithelial cells) on the white blood cell FSC signal. If the CR(WBC)-CW-FSC-P gain value is set inaccurately, for example, the gain value is too low, the FSC signals of other cells will interfere with the signals of white blood cells, resulting in a high white blood cell count. Conversely, if the gain value is too high, the signals of some white blood cells may be suppressed, resulting in a low white blood cell count. In actual operation, due to the complexity and diversity of urine samples, the CR(WBC)-CW-FSC-P gain value should be adjusted according to different situations to obtain more accurate analysis results. Summary of the invention

[0005] The problem to be solved by the present invention is that the existing urine formed component analyzer UF-5000 has a high false positive rate of white blood cells for samples with increased epithelial cells, thereby increasing the misdiagnosis rate of urinary tract infection. The present invention overcomes the above problems in the prior art and provides a method for effectively reducing the false positive rate of white blood cell detection of UF-5000. To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A method for reducing the false positive rate of leukocyte detection by a UF-5000 urine formed component analyzer, wherein the method for reducing the false positive rate of leukocyte detection by a UF-5000 urine formed component analyzer comprises the following specific steps:

[0007] Step 1: Determine the specimens that may contain false positive results for white blood cells: Use the [REVIEW determination setting] function in the UF-5000 urine formed component analyzer to mark the sample results that meet the conditions;

[0008] Step 2: Change the CR(WBC)-CW-FSC-P gain value in the UF-5000 urine formed component analyzer: Set the CR(WBC)-CW-FSC-P gain value of the UF-5000 urine formed component analyzer to the optimal range to reduce the interference of epithelial cells with white blood cell detection;

[0009] Step 3: Re-examine and review the samples marked in step 1: Under the condition of the optimal range of CR (WBC)-CW-FSC-P gain value in step 2, re-examine the samples marked in step 1. If the white blood cell result turns negative, the UF-5000 urine formed element analyzer ends the test and sends a test report; if the white blood cell result is still positive, perform manual microscopic review and review the result.

[0010] The present invention discloses a method for reducing the false positive rate of leukocyte detection by a UF-5000 urine formed component analyzer, wherein the conditions in step 1 are that the leukocyte count is greater than 10 / μL and the epithelial cell count is greater than 12 / μL.

[0011] The present invention discloses a method for reducing the false positive rate of leukocyte detection by a UF-5000 urine formed component analyzer. In the step 1, the [REVIEW determination setting] function in the UF-5000 urine formed component analyzer is used to mark sample results that meet the conditions. Specifically, a condition is set and a "Rev" mark is displayed for the results that meet the condition.

[0012] The present invention discloses a method for reducing the false positive rate of leukocyte detection by a UF-5000 urine formed component analyzer, wherein the optimal range in step 2 is 1.08-1.18.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention discloses a method for reducing the false positive rate of leukocytes detected by a UF-5000 urine formed component analyzer, which can significantly reduce the false positive rate of leukocytes in the detection results of the UF-5000 urine formed component analyzer, increase the accuracy of the results, thereby reducing the misdiagnosis of urinary tract infection caused by false positive leukocytes, improving the prognosis of patients and reducing unnecessary use of antibiotics; after the CR (WBC)-CW-FSC-P gain value of the UF-5000 is adjusted to within the range of 1.08-1.18, the false positive rate of urine leukocytes detected by the analyzer is greatly reduced from 32.12% to less than 10%, the Youden index can reach an optimal value of 69.62%, and the AUC is greater than 0.8; compared with manual microscopy, the method has the advantages of being simpler, faster, and having low requirements on the level of operators, and compared with the semi-quantitative "individuals / HP" format of manual microscopy, the method can retain the full quantitative method in the "individuals / μl" format for reporting. Accurate quantitative reporting is conducive to dynamic observation of the development of the disease and the treatment effect. DETAILED DESCRIPTION

[0015] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Example 1: A method for reducing the false positive rate of leukocytes detected by a UF-5000 urine formed component analyzer, wherein the method for reducing the false positive rate of leukocytes detected by a UF-5000 urine formed component analyzer comprises the following specific steps:

[0017] Step 1: Set up the UF-5000 to mark the results of epithelial cell increase and combined white blood cell positive to indicate the possible existence of false positive white blood cell results. Specifically, in the [REVIEW Judgment Settings] of the UF-5000, set the judgment limits of white blood cell count>10 / μL and epithelial cell count>12 / μL. When a urine test result that meets the judgment appears, "Rev" will be displayed in the test result information of the corresponding sample to indicate that there may be false positive white blood cells and the white blood cell results need to be confirmed. At this time, the measurement has been completed and the data has been saved. Find the corresponding urine samples that meet the judgment for re-examination, and the samples that do not meet the judgment can be reviewed for white blood cell results. The purpose of this step is to identify samples that may have false positive white blood cells and prepare for the next step.

[0018] Step 2: Change the CR(WBC)-CW-FSC-P gain value and retest the sample in the previous step. Set the CR(WBC)-CW-FSC-P gain value from the default value of 0.88 to the range of 1.08-1.18. Then retest the sample in step one to eliminate possible false positives of white blood cells. Specifically, log in to the instrument with sysmex, enter (service)-(service factory)-(Sensitivity adjustment), adjust the sensitivity, and adjust the CR(WBC)-CW-FSC-P gain value to the range of 1.08-1.18. The purpose of this step is to adjust the electrical signal compensation of the white blood cell FSC, thereby reducing the influence of epithelial cells on the white blood cell FSC signal and reducing the false positive rate of white blood cells without significantly inhibiting the optimal value of the white blood cell signal, in preparation for the next retest.

[0019] Step 3: Place the urine sample that meets the criteria in step 1 into the test tube rack, put the test tube rack containing the sample back into the injector, and the instrument automatically retests. If the white blood cell result turns negative (WBC≤10 / μL), the test is terminated and the white blood cell result is reviewed. The false positive rate of white blood cells in the retest results dropped from 32.12% to less than 10%. If the white blood cell result is still >10 / μL, the white blood cell result is reviewed after manual microscopic examination to further exclude false positive white blood cells.

[0020] For samples where epithelial cells may interfere with the leukocyte detection signal and cause false positives (i.e., leukocyte count>10 / μl, epithelial cell count>12 / μl), the CR(WBC)-CW-FSC-P gain value was adjusted to try to reduce the leukocyte false positive rate. In order to explore the appropriate gain value, we performed urine leukocyte detection by adjusting to different gain values. We found that the false positive rate of leukocytes decreased with the increase of CR(WBC)-CW-FSC-P gain value, while the false negative rate increased with the increase. When the CR(WBC)-CW-FSC-P gain value increased from the original 0.88 to the range of 1.08-1.18, the interference of epithelial cells on leukocyte signals could be greatly reduced, and the false positive rate of leukocytes was greatly reduced from 32.12% to below 10%. At the same time, the Youden index (an accuracy indicator) reached the optimal value of 69.62%, and the AUC (area under the ROC curve, an indicator of diagnostic efficacy) was greater than 0.8, indicating that it had a good discrimination ability at this time (Table 1).

[0021] For samples with increased epithelial cells, setting the CR(WBC)-CW-FSC-P gain value to the range of 1.08-1.18 can significantly reduce the false positive rate of UF-5000 detection of white blood cells when epithelial cells increase, without significantly increasing the false negative rate, thereby improving the accuracy of white blood cell detection.

[0022] Table 1: Performance of UF-5000 in detecting urine leukocytes at different CR(WBC)-CW-FSC-P gain values

[0023]

[0024] In addition, for cases where epithelial cell hyperplasia may interfere with leukocyte detection, although this method significantly reduces the false positive rate of leukocytes, there are still 20.59%-23.53% false positives. Therefore, manual microscopy should still be used as the gold standard.

[0025] Example 2: In actual operation, the operator loads sample 1 into the injector of the Sysmex UF-5000 urine analyzer. The instrument has pre-set white blood cell count>10 / μL and epithelial cell count>12 / μL as the false positive warning standards for white blood cells. The analyzer starts the detection program and completes the analysis of sample 1. The result display shows: the white blood cell count is 18 / μL and the epithelial cell count is 35 / μL. Since the result meets both preset conditions, the result interface of sample 1 displays the "Rev" mark, indicating that there may be a false positive for white blood cells. The operator records the initial result. Subsequently, the operator logs into the system menu of the instrument, enters the "Service" mode, finds the "Sensitivity adjustment" submenu, and selects the CR(WBC)-CW-FSC-P parameter. The gain value of the parameter is manually adjusted from the default value of 0.88 to 1.12, and the change is confirmed. The operator takes out sample 1, loads it into the injector again, and starts the instrument for re-inspection. The retest results show that the white blood cell count is 5 / μL and the epithelial cell count is 42 / μL. The "Rev" mark disappears. Since the white blood cell count is lower than 10 / μL, it is judged as negative. The operator reviews and records the retest results, ending the test process for sample 1.

[0026] Example 3: In actual operation, the operator loads sample 2 into the injector of the Sysmex UF-5000 urine analyzer. The initial test results of sample 2 show that the white blood cell count is 25 / μL and the epithelial cell count is 60 / μL. The result interface of sample 2 is marked "Rev". The operator records the initial results. The operator logs into the system menu of the instrument, enters the "Service" mode, finds the "Sensitivity adjustment" submenu, and selects the CR(WBC)-CW-FSC-P parameter. The gain value of this parameter is manually adjusted from the default value of 0.88 to 1.12, and the change is confirmed. The operator takes out sample 2, loads it into the injector again, and starts the instrument for re-examination. The re-examination results show that the white blood cell count is 15 / μL and the epithelial cell count is 68 / μL. The "Rev" mark still exists. Since the white blood cell count is still higher than 10 / μL, the operator takes out sample 3 according to the standard operating procedure, prepares microscope slides, and performs manual microscopic examination under a microscope. The microscopic examination result shows that the white blood cell count is 12 / HPF. The operator records the manual microscopic examination result and reviews the final white blood cell count of sample 3, ending the testing process for sample 3.

[0027] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for reducing the false positive rate of leukocyte detection by UF-5000 urine formed component analyzer, characterized in that: The method for reducing the false positive rate of leukocyte detection by the UF-5000 urine formed component analyzer specifically comprises the following steps: Step 1: Determine the specimens that may contain false positive results for white blood cells: Use the [REVIEW determination setting] function in the UF-5000 urine formed component analyzer to mark the sample results that meet the conditions; Step 2: Change the CR(WBC)-CW-FSC-P gain value in the UF-5000 urine formed component analyzer: Set the CR(WBC)-CW-FSC-P gain value of the UF-5000 urine formed component analyzer to the optimal range to reduce the interference of epithelial cells with white blood cell detection; Step 3: Re-examine and review the samples marked in step 1: Under the condition of the optimal range of CR (WBC)-CW-FSC-P gain value in step 2, re-examine the samples marked in step 1. If the white blood cell result turns negative, the UF-5000 urine formed element analyzer ends the test and sends a test report; if the white blood cell result is still positive, perform manual microscopic review and review the result.

2. The method for reducing the false positive rate of leukocyte detection by UF-5000 urine formed component analyzer according to claim 1, characterized in that: The condition in step 1 is that the white blood cell count is >10 / μL and the epithelial cell count is >12 / μL.

3. The method for reducing the false positive rate of leukocyte detection by UF-5000 urine formed component analyzer according to claim 1, characterized in that: In the step 1, the [REVIEW judgment setting] function in the UF-5000 urine formed component analyzer is used to mark the sample results that meet the conditions. Specifically, a condition is set and a "Rev" mark is displayed for the results that meet the condition.

4. The method for reducing the false positive rate of leukocyte detection by UF-5000 urine formed component analyzer according to claim 1, characterized in that: The optimal range in step 2 is 1.08-1.18.

Images