Objective To analyze the consistency between the results of human immunodeficiency virus (HIV) screening test and confirmatory test results and to explore factors associated with false positive in screening test.
Methods A total of 1 012 cases of HIV antibody positive in screening test were confirmed with Western blot (WB). The results of WB were compared with those of screening test according to the age distribution, test method and signal to cut-off (S/CO) value.
Results The confirmed positive rate for all the samples was 37.6% (381/1 012). The confirmed positive rate for the female cases (6.9%) was much lower than that of the male cases (53.8%) and the positive rate of the cases over 60 years old was 15.2%, significantly lower than that of the cases of other ages. The positive rate of confirmatory test differed significantly by detection methods in the screening test, with the lowest for those with luminescence method (32.6%) and the highest with rapid method (85.1%). The confirmatory positive rate was only 1.1% for the results with the S/CO value of < 5 by luminescence method.
Conclusion The high false positive rate in initial screening is related to specific examinees and is greatly affected by detection method. The extensive application of luminescence method is an important reason for the increase of false positive, and low value results of the luminescence method are mostly false positive.
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