Significance of false positive syphilis reactions and anticardiolipin antibodies in a nationwide series of pregnant women.

Abstract

The highly sensitive rapid plasma reagin (RPR) and Treponema pallidum hemagglutination tests were used to determine the frequency of false positive syphilis reactions in a nationwide series of pregnant women in Finland. The frequency found was 14/10,000. Two cases of systemic lupus and 2 of undefined connective tissue disease were found during a 20-month period among 134 false positive reactors in a series of 110,000 separate pregnancies. The risk of subsequent fetal loss among false positive syphilis reactors was 7%, similar to the risk in RPR negative controls. Half of the sera in the highest RPR titer groups and 1/3 in the lowest titer groups had elevated levels of anticardiolipin antibodies in solid-phase enzyme immunoassay. This assay did not increase the risk of clinical disease or subsequent fetal loss above the risk of RPR test alone.