Patient characteristics
| Demographics and baseline characteristics | n = 40 |
| Age at first iTTP episode (yr), median (IQR) | 47 (32-54) |
| Age at azathioprine start (yr), median (IQR) | 49 (38-58) |
| Female sex, n (%) | 31 (78) |
| Ethnicity, n (%) | |
| Caucasian | 39 (98) |
| Black | 1 (2) |
| 0 blood group, n (%)* | 13 (46) |
| BMI (kg/m2), median (IQR) | 26 (23-31) |
| First iTTP episode, n (%) | 15 (38) |
| ADAMTS13 activity before azathioprine start, n (%)† | |
| ADAMTS13 <10% | 20 (62) |
| 10%≤ADAMTS13<20% | 5 (16) |
| 20%≤ADAMTS13<45% | 5 (16) |
| ADAMTS13 ≥45% | 2 (6) |
| Exposure, median (IQR) | |
| Azathioprine dosage, mg/kg per d | 1.3 (1-1.6) |
| Duration of azathioprine treatment, mo | 16 (8-45) |
| Autoimmune comorbidities, n (%) | |
| Patients with ≥1 autoimmune comorbidity | 15 (38) |
| Patients with: | |
| 1 autoimmune comorbidity | 12 (30) |
| 2 autoimmune comorbidities | 2 (5) |
| 3 autoimmune comorbidities | 1 (2) |
| List of autoimmune comorbidities, n (%) | |
| Hashimoto thyroiditis | 9 (47) |
| Systemic lupus erythematosus | 3 (16) |
| Raynaud disease | 2 (11) |
| Evans syndrome | 1 (5) |
| Chronic urticaria | 1 (5) |
| Graves’ disease | 1 (5) |
| Sjogren’s syndrome | 1 (5) |
| Immune thrombocytopenic purpura | 1 (5) |
| Demographics and baseline characteristics | n = 40 |
| Age at first iTTP episode (yr), median (IQR) | 47 (32-54) |
| Age at azathioprine start (yr), median (IQR) | 49 (38-58) |
| Female sex, n (%) | 31 (78) |
| Ethnicity, n (%) | |
| Caucasian | 39 (98) |
| Black | 1 (2) |
| 0 blood group, n (%)* | 13 (46) |
| BMI (kg/m2), median (IQR) | 26 (23-31) |
| First iTTP episode, n (%) | 15 (38) |
| ADAMTS13 activity before azathioprine start, n (%)† | |
| ADAMTS13 <10% | 20 (62) |
| 10%≤ADAMTS13<20% | 5 (16) |
| 20%≤ADAMTS13<45% | 5 (16) |
| ADAMTS13 ≥45% | 2 (6) |
| Exposure, median (IQR) | |
| Azathioprine dosage, mg/kg per d | 1.3 (1-1.6) |
| Duration of azathioprine treatment, mo | 16 (8-45) |
| Autoimmune comorbidities, n (%) | |
| Patients with ≥1 autoimmune comorbidity | 15 (38) |
| Patients with: | |
| 1 autoimmune comorbidity | 12 (30) |
| 2 autoimmune comorbidities | 2 (5) |
| 3 autoimmune comorbidities | 1 (2) |
| List of autoimmune comorbidities, n (%) | |
| Hashimoto thyroiditis | 9 (47) |
| Systemic lupus erythematosus | 3 (16) |
| Raynaud disease | 2 (11) |
| Evans syndrome | 1 (5) |
| Chronic urticaria | 1 (5) |
| Graves’ disease | 1 (5) |
| Sjogren’s syndrome | 1 (5) |
| Immune thrombocytopenic purpura | 1 (5) |