Syphilis serology testing: a comparative study of Abbot Determine, Rapid Plasma Reagin (RPR) card test and Venereal Disease Research Laboratory (VDRL) methods.

Blood from 2100 women attending the antenatal clinic of the Port Moresby General Hospital (PMGH) and the 9 Mile urban clinic of Port Moresby was tested for syphili using the laboratory-based Venereal Disease Research Laboratory (VDRL) syphilis serology test and two clinic-based syphilis tests, Abbot Determine and Abbot Syfacard-RR (Rapid Plasma Reagin (RPR) card test). The Abbot Determine and the Syfacard-R tests were compared with the VDRL test, the gold standard in this study. The validation test results of Determine versus VDRL were as follows: sensitivity 92.0%; specificity 94.6%; the predictive value of a positive test 42.6%; and the predictive value of a negative test 99.6%. The validation tests for RPR versus VDRL were as follows: sensitivity 56.3% specificity 96.5%; predictive value of a positive test 41.2%; and the predictive value of a negative test 98.1%. The RPR test costs 3.5 kina (about one US dollar) a test, the VDRL less than 1 kina a test whilst the Determine test kit costs about 5 kina a test. When laboratory time, salaries and other supplies are costed the Determine test is expected to cost relatively much less. Our recommendation is that the Determine test be made available in areas of the country where VDRL is unavailable or where logistics do not allow for test results to be available early enough to make a difference to the care of th pregnant woman and her fetus.