An abnormal and rapidly doubling AT at presentation is more typical in severely poisoned patients, as judged by the effects on clotting. These data suggest that risk prediction instruments may be improved by incorporating both the serum AT concentration at initiation of antidotal therapy and its rate of change. Further studies using such an approach are warranted.

The APAP × AT multiplication product, calculated at the time of presentation and after several h of antidotal therapy, holds promise as a new risk predictor following APAP overdose. It requires neither graphical interpretation nor accurate time of ingestion, two limitations to current risk stratification.