the low-end sensitivity of the assay by decreasing the time
spent at each thermal cycling step in the amplification profile.
The results confirm that the discrepancies predominate among
the low-copy, or weak, positives, while all other results are
consistent, independent of the profile used. These results re-
flect the inherent variability in sensitivity that results from
seemingly minor changes in protocol. Thus, it is recommended
that changes to standardized protocols be accompanied by
revalidated assays and appropriately redefined performance
criteria.