TABLE 4.

Comparison of three possible strategies for combination ENA testing

Testing strategyAdvantagesDisadvantages
ELISA followed by CIEPRapid turnaround time, especially for negative resultsLimited range of anti-ENA antibodies screened by ELISA
High sensitivity of ELISA combined with high specificity of CIEPMay miss other anti-ENA antibodies, which would be detected as unidentified precipitin lines by CIEP
Cost of ELISA-based kits
CIEP followed by CIEPInexpensiveLow sensitivity for 52-kDa SS-A, SS-B, and Scl-70
High specificity
Detects wide range of anti-ENA antibodies in addition to the six most common, i.e., anti-SS-A, anti-SS-B, anti-Sm, anti-U1 RNP, anti-Scl-70, and anti-Jo-1Slow turnaround time, especially for difficult samples
Need to maintain a “backup” method for difficult samples
CIEP followed by ELISASlow turnaround time
Low sensitivity of CIEP combined with low specificity of ELISA