TABLE 4.

Comparison of three possible strategies for combination ENA testing

Testing strategy	Advantages	Disadvantages
ELISA followed by CIEP	Rapid turnaround time, especially for negative results	Limited range of anti-ENA antibodies screened by ELISA
	High sensitivity of ELISA combined with high specificity of CIEP	May miss other anti-ENA antibodies, which would be detected as unidentified precipitin lines by CIEP
		Cost of ELISA-based kits
CIEP followed by CIEP	Inexpensive	Low 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-1	Slow turnaround time, especially for difficult samples
Need to maintain a “backup” method for difficult samples
CIEP followed by ELISA		Slow turnaround time
		Low sensitivity of CIEP combined with low specificity of ELISA