Detection and analysis of syphilis antibody in 80 478 cases of inpatients

Objective To understand the infection and distribution of syphilis in hospitalized patients, thus to provide reference for syphilis prevention and control. Methods TP-ELISA test was used to examine early syphilis antibody, and adopted the TPPA test to validation syphilis antibody, and TRUST was used to determine the titer of syphilis antibody in 80 478 hospitalized patients from January 2015 to November 2017, then the results were retrospectively analyzed. Results Among 80 478 inpatients, 1 326 cases were positive by TP-ELISA test(1 223 cases positive, 101 cases weak positive and 2 cases negative by TPPA confirmed). The positive rates of TP-ELISA in different years were 1.62%(445/27 394), 1.72%(490/28 412) and 1.58%(389/24 672), respectively, and the difference was not statistically significant(P>0.05). The positive rates of male and female patients were 2.02%(689/33 985) and 1.37%(635/46 479), and the difference was statistically significant(χ2=52.91, P=0.00). The positive rates of ≤18 years old, >18-59 years old, >59-79 years old and>79 years old were 0.32%(7/2 161), 1.44%(765/53 001), 2.31%(488/21 163) and 1.50%(62/4 153), respectively.The highest proportion of syphilis patients was in the group of >59-79 years old, and the differences were statistically significant compared with the other groups(χ2=37.08, 67.05, 10.80, all P<0.01). Among the TP-ELISA positive patients, 54.90%(728/1 326) had TRUST titer negative, 36.50%(484/1 326) had titer less than 1∶8, and the others had 8.44%(112/1 326). Conclusion The incidence of syphilis was higher in males than in females in 80 478 hospitalized patients.The highest positive rate was found in >59-79 years old group, and the number of elderly cases increased rapidly.Therefore, the effective interventions should be developed to control the transmission of syphilis according to the epidemiological features. Key words: Inpatients; Syphilis; Antibodies; Syphilis serodiagnosis; Enzyme-linked immunosorbent assay; Agglutination tests; False positive reactions; Laboratory techniques and procedures