highly significantP < .001
There was a highly significant correlation between the 2 methods when the assay was changed from RIA to ACS-180 in 1998 ( P < .001; r 2 = 0.94) and when it was changed from ACS-180 to DELFIA in 2003 ( P < .001; r 2 = 0.99). 100% agreement for screening passes and failures was obtained using the revised cut-off values.