Comparison of patients with idiopathic TTP with and without severe ADAMTS13 deficiency
| Demographic/clinical feature . | ADAMTS13 < 10% (n = 51) . | ADAMTS13 ≥ 10% (n = 56) . | P . |
|---|---|---|---|
| Median age, y (range) | 41 (9-71) | 57 (2-85) | < .001 |
| Sex (% women) | 80 | 66 | .096 |
| Race (% black) | 37 | 20 | .043 |
| Neurologic abnormalities, % | |||
| Major | 35 | 39 | .760 |
| Minor | 31 | 34 | |
| None | 34 | 27 | |
| Laboratory data (median) | |||
| Platelet count, μL | 17 000 | 43 500 | < .001 |
| Hematocrit, percentage | 25 | 27 | .043 |
| LDH, U/L | 1257 | 989 | .242 |
| Creatinine, mg/dL | 1.1 | 3.3 | < .001 |
| Renal failure, μmol/L | 97.2 | 291.7 | |
| Acute renal failure | 6 | 50 | < .001 |
| Mild renal insufficiency | 41 | 32 | |
| Normal renal function | 53 | 18 | |
| Clinical course | |||
| Dialysis, % | 4 | 43 | < .001 |
| Death, % | 18 | 21 | .623 |
| Plasma exchange,* median (range) | 19 (3-79) | 9 (3-71) | < .001 |
| Relapse,* % | 40 | 7 | < .001 |
| Demographic/clinical feature . | ADAMTS13 < 10% (n = 51) . | ADAMTS13 ≥ 10% (n = 56) . | P . |
|---|---|---|---|
| Median age, y (range) | 41 (9-71) | 57 (2-85) | < .001 |
| Sex (% women) | 80 | 66 | .096 |
| Race (% black) | 37 | 20 | .043 |
| Neurologic abnormalities, % | |||
| Major | 35 | 39 | .760 |
| Minor | 31 | 34 | |
| None | 34 | 27 | |
| Laboratory data (median) | |||
| Platelet count, μL | 17 000 | 43 500 | < .001 |
| Hematocrit, percentage | 25 | 27 | .043 |
| LDH, U/L | 1257 | 989 | .242 |
| Creatinine, mg/dL | 1.1 | 3.3 | < .001 |
| Renal failure, μmol/L | 97.2 | 291.7 | |
| Acute renal failure | 6 | 50 | < .001 |
| Mild renal insufficiency | 41 | 32 | |
| Normal renal function | 53 | 18 | |
| Clinical course | |||
| Dialysis, % | 4 | 43 | < .001 |
| Death, % | 18 | 21 | .623 |
| Plasma exchange,* median (range) | 19 (3-79) | 9 (3-71) | < .001 |
| Relapse,* % | 40 | 7 | < .001 |
Data are presented for the 107 patients with idiopathic TTP, comparing patients with ADAMTS13 activity less than 10% with patients with ADAMTS13 activity more than or equal to 10%. Among the 56 patients with ADAMTS13 activity more than or equal to 10%, 28 patients had normal ADAMTS13 activity (> 50%), 18 patients had mildly deficient activity (25%-50%), and 10 patients had moderately deficient activity (10%–24%). Neurologic abnormalities and renal failure categories have been previously defined.17 Neurologic abnormalities and laboratory data are from the day of diagnosis, defined as the day of the first plasma exchange treatment. Renal failure categories included data at diagnosis plus or minus 7 days. Laboratory data and the number of plasma exchange treatments are presented as median values. Deaths occurred within 30 days of the last plasma exchange treatment. The 3 patients who initially had ADAMTS13 activity more than or equal to 10% and who subsequently relapsed included 2 previously described patients with abnormal but not initially deficient ADAMTS13 activity14 (Table 5, patients 4 and 5) and one child with atypical HUS.
Number of plasma exchange treatments and frequency of relapse are presented for the 42 surviving patients with ADAMTS13 less than 10% and the 44 surviving patients with ADAMTS13 activity more than or equal to 10%.