To investigate the detection of treponema pallidum (TP) antibodies of patients in outpatient and inpatient clinics and the false positive samples screened by chemiluminescence microparticle immunoassay (CMIA) to evaluate the application value of CMIA in anti-TP detection.

CMIA was used to screen 44 558 clinical specimens for TP-specific antibodies in the outpatient and inpatient clinics of Beijing Jiangong Hospital from January 2017 to December 2019. The positive samples of anti-TP were furtherly confirmed by the Treponema pallidum particle agglutination test (TPPA) and rapid plasma reagin ringing card test (RPR) detection, the results of anti-TP screening, RPR titer and the analysis of different age stages and gender groups were statistically analyzed by SPSS 25.0, respectively.

Total of 44 558 serum samples were screened for anti-TP by CMIA, and 996 samples with positive anti-TP were detected. And 898 positive samples were confirmed by TPPA. Compared with the positive results confirmed by CMIA and TPPA, the false positive rate was 0.22% (98/44 558), the positive predictive value was 90.16% (898/996), and the specificity was 99.78% (43 660/43 758). For samples with S/CO values greater than 9, the positive predictive value of TPPA confirmed was 100.00% (898/898), and the S/CO value was divided into 5 groups of 1-2, 2-3, 3-5, 5-9 and > 9, and TPPA positive predictive value difference was statistically significant (χ² = 309.81, P < 0.001). Among the 996 RPR detected samples, 336 cases were positive for RPR, and samples with titers ≤ 1︰8 accounted for 84.23% (283/336) of the positive samples for RPR. The positive rate of ≥ 80 years old group was the highest. The positive rate of positive samples confirmed by TPPA was 2.76% (84/3 042), which was higher than the overall positive rate of 2.02% (898/44 558), with significant difference (χ² = 7.84, P = 0.005). The positive detection rate confirmed by TPPA for males was 2.68% (467/17 413), which was 1.59% (431/27 145) for females, with significant difference (χ² = 64.31, P < 0.001). The 40-59 years old group of samples detected by RPR had the highest positive rate of 0.84% ??(124/14 810), which was higher than the overall positive rate [0.75% (336/44 558)]. The positive detection rate detected by RPR for males was 1.05% (182/17 413), which was 0.57% (154/27 145) for females, with significant difference (χ² = 32.37, P < 0.001).

The syphilis serology test adopts the strategy of CMIA combined with TPPA and RPR detection was effective. The analysis of anti-TP positive results for special populations, high-risk populations and key departments should be noticed. Correct detection, accurate and timely reporting, and reasonable interpretation of syphilis serum test results were extremely important.