Comparison of Manual and Fully Automated AIX1000 Rapid Plasma Reagin Assays for Laboratory Diagnosis of Syphilis

Abstract

The analytical performance of the AIX1000 system, a fully automated and recently FDA-cleared rapid plasma reagin (RPR) system, was evaluated by comparison to a manual RPR test in a traditional syphilis testing algorithm. A total of 1,028 consecutive serum samples submitted for syphilis testing to the University of North Carolina Hospitals Clinical Immunology Laboratory were tested per each manufacturer's instructions. Among those samples, 996 were nonreactive and 20 were reactive using both the ASI RPR card system and the AIX1000 system. Of the 12 discrepant specimens, 11 were AIX1000 reactive and ASI card nonreactive whereas 1 specimen was ASI card reactive and AIX1000 nonreactive. The sensitivity and specificity of the manual ASI card were 76.0% and 99.8%, respectively, while the sensitivity and specificity of the AIX100 were 100.0% and 99.4%, respectively (sensitivity = 0.03). Among the 20 concordant reactive specimens, 68.4% of the titers agreed within ±1 dilution between methods. Reproducibility testing of the AIX1000 system demonstrated qualitative and semiquantitative (within ±1 dilution) agreement between specimens tested on different days of 96.0% and 76.0%, respectively, and 100.0% agreement between replicates within the same run. One of 24 samples analyzed under other disease conditions was reactive on both the AIX1000 system and the ASI card. Overall, the fully automated AIX1000 system demonstrated significantly enhanced sensitivity and specificity similar to that of the manual ASI RPR card test, making the AIX1000 system suitable for the laboratory diagnosis of syphilis in a clinical laboratory setting.

Efektivitas Pemeriksaan Serologis Sifilis

“…15,17,21,24 RPR menunjukkan sensitivitas 9,1%-100%, spesifisitas 80,8%-100%, NRP 76,2%-100%, dan NRN 65,5%-100%. 13,16,[18][19][20][21][22]26,27 Selain itu, RPR dibandingkan TPHA memiliki observed percentage of agreement (Po) 88,0%. 20 Berdasarkan stadium sifilisnya, sensitivitas RPR pada stadium sifilis primer jauh lebih baik daripada VDRL, akan tetapi pada stadium sifilis sekunder hasil sensitivitas lebih baik terlihat pada VDRL.…”

“…RPR otomatis memiliki sensitivitas 52,5%-100%, spesifisitas 94,3%-99,4%, NRP 80,7%-92,5%, dan NRN 99,4%-100%. 18,19,27 Sementara itu, RPR kartu memiliki sensitivitas 76%-86,4%, spesifisitas 94,3%-99,8%, NRP 90,5%, dan NRN 99,4%. 18,19 Sensitivitas yang tinggi menandakan rendahnya hasil negatif palsu, sedangkan jika sensitivitasnya rendah artinya terdapat banyak hasil negatif palsu.…”

“…18,19,27 Sementara itu, RPR kartu memiliki sensitivitas 76%-86,4%, spesifisitas 94,3%-99,8%, NRP 90,5%, dan NRN 99,4%. 18,19 Sensitivitas yang tinggi menandakan rendahnya hasil negatif palsu, sedangkan jika sensitivitasnya rendah artinya terdapat banyak hasil negatif palsu. 38,41 Pada penelitian untuk menentukan ada tidaknya sifilis kongenital pada bayi baru lahir, sensitivitas RPR yang rendah terlihat sebesar 9,1%.…”

“…44 RPR otomatis dan RPR kartu memiliki κ 0,565-0,940 yang artinya terdapat kesepakatan sedang sampai hampir sempurna. 18,19,27,44 Sementara itu, κ dari TP Rapid dan TPHA sebesar 0,917 menunjukkan kesepakatan hampir sempurna. 24,44 Pada literatur yang meneliti berbagai jenis TP Rapid dibandingkan dengan Chemiluminescent Microplate Immunoassay (CMIA), TPHA, dan FTA-ABS mempunyai κ 0,85-1 yang artinya terdapat kesepakatan hampir sempurna.…”

“…29,44 Sensitivitas dari RPR, VDRL, dan TP Rapid termasuk dalam kategori tinggi. 12,13,[15][16][17][18][19][20][21][22]24,[26][27][28][29][30][31][32][33][34] Spesifisitas tinggi didapatkan pada TPHA dan TP Rapid. 12,24,[28][29][30][31][32][33][34][35] RPR dan VDRL digunakan sebagai skrining karena sensitivitasnya yang tinggi.…”