Evaluation of the Rheuma-Lex latex agglutination test for detection of rheumatoid factor.

The performance of the Trinity Laboratories Rheuma-Lex latex agglutination test kit for detection of Rheumatoid factor (RF) in patient sera was evaluated. The method and test results of the Rheuma-Lex test were compared to those obtained with another commercially available latex agglutination test kit (RapiTex RF Test) on 162 sera submitted for RF testing. Discrepant results were resolved by testing those sera with a third commercially available kit. The Rheuma-Lex and the RapiTex kits demonstrated sensitivities of 100 and 87%, specificities of 98 and 99%, negative predictive values of 100 and 97%, positive predictive values of 94 and 94% and efficiencies of 99 and 97% respectively. The Rheuma-Lex test kit was judged to be a sensitive, reliable and simple assay for RF detection in serum.