An evaluation of two new screening tests for rheumatoid factors

Two further commercial screening tests for rheumatoid factors have been evaluated using both the sheep cell agglutination (SCAT) test and the Rheumaton slide test used routinely in this laboratory. In the group of sera tested, the Rheumaton test detected all sera with elevated SCAT titres; the Searle RA Latex test failed to detect a few of these sera. The Rheumaton test gave many misleading positive reactions with sera having insignificant SCAT titres. Far fewer misleading positive results were obtained with the Searle test. The Rythrotex test gave results similar to Rheumaton but was very difficult to use.