Quick Question: PTT-based Phospholipid Neutralization

This question turned up some surprises:

When performing the PTT-based phospholipid neutralization procedure, what limit do you use to confirm lupus anticoagulant?

a. ≥ 8 seconds’ difference between pre- and post-PTT: 8 (33%)
b. Locally computed difference in seconds between pre- and post- PTT: 5 (21%)
c. Ratio ≥ 1.2 between pre- and post-PTT: 4 (17%)
d. Locally computed ratio between pre- and post-PTT: 7 (29%)

Having used mostly integrated Stago Sta-Clot LA kits my whole life, I thought most everyone was using their 8-second difference, but it seems we have a nearly even distribution. Geo.