Analysis Of Influencing Factors For Detection Of Anti-HCV Grey Area By CMIA

Objective To investigate the influencing factors of grey zone results in Hepatitis C virus antibodies（Anti-HCV）by Chemiluminescence microparticle immunoassays（CMIA）method.To improve the accuracy of anti-HCV determination by CMIA method,in order to determine the best critical value for the diagnosis of hepatitis C.Methods Patients who were tested for Anti-HCV with positive result using the CMIA method at the First Hospital of Lanzhou University between July 2017 and June 2019 were enrolled.40 were positive for HCV RNA and 190 were negative.For these 230 patients,the Receiver operating characteristic curve（ROC curve）was used to calculate the optimal cut-off value of CMIA method for Anti-HCV detection.For patients whose Anti-HCV results were in the gray area of 1.0 ≤ S/CO ≤ 5.0,Wilcoxon signed rank analysis was used to compare the effects of ordinary and high-speed centrifugation on the results,and medical history data and conventional biochemical indexes performed at the same period were reviewed.Multiple linear regression was used to analyze the possible influencing factors of grey area results of Anti-HCV detection.For gray area specimens,binary stepwise Logistics regression analysis was applied to establish a joint diagnostic formula of Anti-HCV and other serological indicators,and its diagnostic value was determined.Results 1.A total of 230 patients meeting the inclusion and exclusion criteria of this study were collected.The positive results of Anti-HCV detected by CMIA method were analyzed,and the ROC curve was drawn to show that the AUC was0.896,and the optimal cut-off value corresponding to the maximum Youden index was 10.25.2.The average level of Anti-HCV was 2.20 ± 1.06 S/CO after 3500 rpm ordinary centrifugation and 2.15 ± 1.02 S/CO after 10000 rpm high-speed centrifugation,and the difference was statistically significant.3.The medical history of gray area patients was retrospectively analyzed.There were 15 cases of cholecystitis（t = 2.636,P = 0.009）,16 cases of hepatitis B（t = 3.048,P = 0.003）,and6 cases of cerebral infarction（t = 2.593,P = 0.009）.P = 0.011)and 14 cases of benign tumors（t = 2.043,P = 0.043）.These patients were more likely to produce grey areas by Anti-HCV detection,and the grey area detection value was higher than that of patients without the above-mentioned diseases.There were 29 patients with malignancy（t =-3.108,P = 0.002）and 6 patients with previous appendectomy（t =-2.422,P = 0.017）,and the grey area results of these patients were lower than those of patients without the previous history,showing a negative correlation.In terms of conventional biochemical indicators,the higher the Calcium ion(Ca²⁺)（t = 2.593,p =0.011）,the higher the value measured;The higher the serum chloride ion concentration（Cl-）（t =-3.161,P = 0.002）and Osmotic pressure（OSM）（t =-2.558,P= 0.012）,the lower the value of detection results.Conclusion 1.Samples with grey area results generated by CMIA method for Anti-HCV detection can be processed by high-speed centrifugation to reduce the probability of grey area results.2.Patients with a history of cholecystitis,hepatitis B,cerebral infarction and benign tumors are more likely to produce grey area results when their blood samples are detected by CMIA than those without such a history;Patients with a history of malignancy or appendectomy were less likely to have grey area outcomes than those without such a history.An increase in the concentration of serum Ca²⁺ and a decrease in the concentration of Cl- may also be one of the factors that interfere with grey zone results in the detection of anti-HCV by the CMIA method.3.When using the CMIA method to detect anti-HCV,S/CO = 10.25 is set as the optimal critical value for the diagnosis of hepatitis C,relative to the S/CO =1.00 as required by the kit,which can improve the accuracy of this test.