Clinical outcome definitions in iTTP
| Initial clinical treatment end points | Clinical response | Sustained platelet count >150 × 109/L, LDH <1.5 ULN, no new end organ symptoms |
| Exacerbation | After clinical response: platelet count <150 × 109/L without other explanation <30 d after last PEX or anti-VWF therapy | |
| Remission definitions | Clinical remission | Sustain clinical response for ≥30 d with no PEX or anti-VWF therapy |
| Complete ADAMTS13 remission | ADAMTS13 activity ≥ULN | |
| Partial ADAMTS13 remission | ADAMTS13 activity ≥20% to LLN | |
| Relapse definitions | Clinical relapse | After clinical remission, platelet count decreases to <150 × 109/L without another explanation, and the need to start iTTP treatment Confirmed by severe ADAMTS13 deficiency |
| ADAMTS13 relapse | After ADAMTS13 remission, ADAMTS13 activity decreases to ≤20% |
| Initial clinical treatment end points | Clinical response | Sustained platelet count >150 × 109/L, LDH <1.5 ULN, no new end organ symptoms |
| Exacerbation | After clinical response: platelet count <150 × 109/L without other explanation <30 d after last PEX or anti-VWF therapy | |
| Remission definitions | Clinical remission | Sustain clinical response for ≥30 d with no PEX or anti-VWF therapy |
| Complete ADAMTS13 remission | ADAMTS13 activity ≥ULN | |
| Partial ADAMTS13 remission | ADAMTS13 activity ≥20% to LLN | |
| Relapse definitions | Clinical relapse | After clinical remission, platelet count decreases to <150 × 109/L without another explanation, and the need to start iTTP treatment Confirmed by severe ADAMTS13 deficiency |
| ADAMTS13 relapse | After ADAMTS13 remission, ADAMTS13 activity decreases to ≤20% |
Adapted from Cuker et al.3
ULN, upper limit of normal; LLN, lower limit of normal.