Table 1.
Assays performed at 15% and 100% antithrombin levels, and impact of antithrombin lowering.
| Assays performed | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| PT assay, s | |||||||||||
| Dade Innovin on BCS XP System (Siemens Healthcare) | Target FVIII level/target AT level (%) | 0/15 | 0/100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | 11.8 (0.1) | 11.6 (0.1) | 11.9 (0.2) | 11.6 (0.1) | 11.8 (0.0) | 11.6 (0.0) | 11.8 (0.1) | 11.7 (0.1) | 11.8 (0.1) | 11.7 (0.1) | |
| % change | 2.0 | 2.6 | 1.7 | 0.9 | 0.3 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | 12.0 (0.1) | 11.9 (0.2) | 11.8 (0.1) | 11.6 (0.2) | 11.5 (0.1) | 11.5 (0.1) | 11.1 (0.2) | 11.2 (0.1) | 10.7 (0.3) | 10.9 (0.2) | |
| % change | 0.8 | 2.0 | 0.3 | −0.6 | −2.4 | ||||||
| HemosIL RecombiPlasTin 2G on ACL Top 700 (Instrumentation Laboratory) |
Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | 13.1 (0.3) | 12.6 (0.2) | 13.2 (0.3) | 12.7 (0.1) | 13.1 (0.1) | 12.7 (0.1) | 13.3 (0.1) | 12.7 (0.1) | 13.1 (0.2) | 12.5 (0.3) | |
| % change | 4.0 | 4.2 | 3.4 | 4.5 | 4.8 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | 13.7 (0.1) | 13.5 (0.6) | 13.5 (0.3) | 13.2 (0.2) | 13.1 (0.4) | 12.9 (0.1) | 12.8 (0.4) | 12.5 (0.22) | 12.4 (0.4) | 12.4 (0.11) | |
| % change | 1.0 | 2.3 | 1.3 | 2.4 | 0.0 | ||||||
| TT assay, s | |||||||||||
| BC Thrombin Reagent on BCS XP System | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | 19.1 (1.1) | 18.6 (0.1) | 18.4 (0.3) | 18.7 (0.2) | 18.4 (0.2) | 18.6 (0.2) | 18.5 (0.2) | 19.0 (0.2) | 18.4 (0.5) | 19.0 (0.5) | |
| % change | 2.5 | −1.4 | −1.2 | −2.9 | −3.5 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | 16.8 (0.2) | 17.1 (0.1) | 16.8 (0.6) | 17.0 (0.5) | 16.6 (0.3) | 16.9 (0.3) | 16.7 (0.5) | 16.8 (0.1) | 16.7 (0.3) | 17.0 (0.2) | |
| % change | −1.8 | −1.4 | −1.8 | −0.8 | −2.1 | ||||||
| aPTT assays, s | |||||||||||
| PTTA (silica) on STA-R Evolution (Diagnostica Stago) | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | 108.4 (1.7) | 101.3 (0.4) | 55.0 (5.3) | 51.6 (0.4) | 38.7 (0.1) | 39.9 (0.3) | 33.8 (0.1) | 35.0 (0.2) | 30.0 (0.1) | 31.3 (1.0) | |
| % change | 7.0 | 6.5 | −3.1 | −3.3 | −4.1 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | 95.4 (0.6) | 99.1 (1.5) | 42.4 (0.9) | 42.1 (0.6) | 33.9 (0.6) | 34.3 (0.1) | 30.1 (0.4) | 30.3 (0.6) | 27.9 (0.2) | 28.7 (0.1) | |
| % change | −3.7 | 0.8 | −1.1 | −0.7 | −2.6 | ||||||
| Dade Actin FSL (ellagic acid) on BCS XP System | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | 67.3 (2.2) | 69.5 (1.7) | 42.1 (2.7) | 44.2 (0.8) | 35.1 (2.2) | 36.1 (0.4) | 29.8 (0.7) | 31.8 (0.1) | 27.0 (0.2) | 28.4 (0.4) | |
| % change | −3.1 | −4.7 | −2.8 | −6.1 | −5.1 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | 66.3 (1.7) | 71.8 (2.8) | 35.1 (0.6) | 35.3 (0.5) | 20.4 (0.7) | 30.2 (0.4) | 27.9 (0.6) | 27.8 (0.4) | 26.2 (0.3) | 26.2 (0.5) | |
| % change | −7.7 | −0.5 | 0.6 | 0.3 | −0.2 | ||||||
| HemosIL SynthASil (silica) on ACL TOP 700 (Instrumentation Laboratory) |
Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | 123.1 (2.0) | 130.9 (1.8) | 51.7 (1.1) | 55.3 (0.2) | 41.3 (0.5) | 43.2 (0.2) | 35.2 (0.4) | 37.3 (0.4) | 31.5 (0.2) | 32.9 (0.4) | |
| % change | −6.0 | −6.5 | −4.3 | −5.6 | −4.3 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | 88.9 (10.6) | 98.2 (16.7) | 43.6 (0.4) | 44.6 (0.2) | 36.2 (0.4) | 36.9 (0.3) | 32.4 (0.3) | 33.2 (0.2) | 30.4 (0.1) | 30.9 (0.6) | |
| % change | −9.4 | −2.3 | −1.8 | −2.4 | −1.5 | ||||||
| CK PREST (kaolin) on STA-R Evolution (Diagnostica Stago) | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | 77.6 (0.2) | 84.1 (1.8) | 44.1 (0.3) | 46.9 (0.5) | 36.5 (0.2) | 37.5 (0.3) | 31.2 (0.1) | 32.5 (0.3) | 27.8 (0.1) | 28.6 (0.3) | |
| % change | −7.7 | −5.8 | −2.6 | −3.9 | −2.6 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | 82.7 (1.8) | 88.5 (4.2) | 39.7 (0.3) | 40.3 (0.2) | 33.0 (0.1) | 33.6 (0.3) | 29.6 (0.2) | 29.8 (0.5) | 27.2 (0.3) | 27.8 (0.1) | |
| % change | −6.6 | −1.5 | −1.7 | −0.6 | −1.9 | ||||||
| FVIII/FIX one-stage activity assays, % | |||||||||||
| Dade Actin FSL (ellagic acid) on BCS XP System | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | NI (NI) | NI (NI) | 6.3 (0.6) | 6.0 (1.0) | 23.3 (2.5) | 24.3 (0.6) | 58.3 (2.1) | 54.0 (1.7) | 119.0 (0.0) | 109.7 (6.1) | |
| % change | NI | 5.0 | −4.1 | 8.0 | 8.5 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | NI (NI) | NI (NI) | 5.0 (1.0) | 5.0 (1.0) | 24.0 (0.0) | 24.0 (0.0) | 59.3 (2.5) | 58.0 (0.0) | 112.3 (2.9) | 108.7 (3.2) | |
| % change | NI | 0.0 | 0.0 | 2.2 | 3.3 | ||||||
| HemosIL SynthASil (silica) on ACL TOP 700 |
Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | NI (NI) | NI (NI) | 6.1 (0.3) | 5.2 (0.3) | 20.5 (1.0) | 18.3 (0.6) | 47.2 (1.8) | 40.8 (1.3) | 91.3 (3.4) | 84.4 (3.2) | |
| % change | NI | 17.4 | 12.0 | 15.6 | 8.2 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | NI (NI) | NI (NI) | 8.3 (0.4) | 8.2 (0.1) | 27.5 (0.7) | 25.5 (0.7) | 64.7 (1.3) | 65.0 (1.0) | 122.8 (1.7) | 109.9 (1.1) | |
| % change | NI | 1.2 | 7.9 | −0.5 | 11.8 | ||||||
| PTTA (silica) on STA-R Evolution | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | NI (NI) | NI (NI) | 6.8 (0.5) | 5.6 (0.1) | 23.1 (0.8) | 22.1 (0.8) | 50.9 (1.5) | 48.2 (1.7) | 103.7 (1.9) | 91.6 (3.3) | |
| % change | NI | 22.6 | 4.2 | 5.7 | 13.2 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | NI (NI) | NI (NI) | 10.2 (0.3) | 10.8 (0.4) | 36.4 (0.4) | 35.2 (0.7) | 70.0 (1.2) | 65.7 (2.5) | 129.6 (4.0) | 108.6 (3.6) | |
| % change | NI | −5.8 | 3.5 | 6.5 | 19.3 | ||||||
| CK PREST (kaolin) on STA-R Evolution | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | NI (NI) | NI (NI) | 6.1 (0.8) | 5.2 (0.3) | 20.9 (0.8) | 21.3 (0.8) | 49.2 (1.3) | 42.9 (0.9) | 95.2 (2.5) | 87.2 (3.0) | |
| % change | NI | 16.6 | −1.7 | 12.2 | 9.1 | ||||||
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | NI (NI) | NI (NI) | 6.5 (0.1) | 6.8 (0.3) | 24.2 (0.8) | 23.7 (0.5) | 57.5 (0.4) | 54.6 (2.2) | 113.5 (3.2) | 98.0 (3.4) | |
| % change | NI | 1.5 | 3.1 | 0.7 | 2.8 | ||||||
| FVIII chromogenic assays | |||||||||||
| FVIII Chromogenic Assay on BCS XP System, % (Siemens Healthineers) | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | 23.6 (3.0) | 22.4 (1.7) | 57.9 (0.3) | 52.5 (3.4) | 110.6 (4.8) | 99.2 (4.3) | |
| % change | NI | NI | 5.6 | 10.3 | 11.5 | ||||||
| Biophen FVIII Chromogenic on the BCS XP System, IU/mL (Siemens Healthineers) | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | NI (NI) | NI (NI) | 0.05 (0.001) | 0.05 (0.001) | 0.2 (0.003) | 0.2 (0.003) | 0.5 (0.001) | 0.4 (0.02) | 1.0 (0.02) | 0.9 (0.008) | |
| % change | NI | 14.1 | 5.9 | 5.8 | 7.5 | ||||||
| FIX chromogenic assays | |||||||||||
| ROX FIX Chromogenic Assay (Rossix) on the BCS XP System, IU/mL | Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | NI (NI) | NI (NI) | 0.04 (0.002) | 0.04 (0.004) | 0.2 (0.007) | 0.2 (0.01) | 0.4 (0.02) | 0.4 (0.06) | 0.8 (0.05) | 0.7 (0.05) | |
| % change | NI | 11.6 | 2.7 | 5.5 | 14.9 | ||||||
| Biophen FIX Chromogenic Assay (Hyphen BioMed) on the BCS XP System, % | Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | NI (NI) | NI (NI) | 3.6 (0.1) | 3.2 (0.1) | 13.5 (0.2) | 11.5 (0.2) | 34.9 (0.9) | 29.6 (0.3) | 66.7 (1.3) | 56.8 (1.5) | |
| % change | NI | 12.6 | 17.7 | 17.8 | 17.4 | ||||||
| Nijmegen inhibitor assays, BU/mL | |||||||||||
| FVIII Dade Actin FSL (ellagic acid) on the BCS XP System | Target FVIII level/target AT level (%) | 0.0/15 | 0.0/100 | 0.1/15 | 0.1/100 | 0.2/15 | 0.2/100 | 0.5/15 | 0.5/100 | 1.0/15 | 1.0/100 |
| Mean (SD) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | |
| FIX Dade Actin FSL (ellagic acid) on the BCS XP System | Target FIX level/target AT level (%) | 0.0/15 | 0.0/100 | 0.1/15 | 0.1/100 | 0.2/15 | 0.2/100 | 0.5/15 | 0.5/100 | 1.0/15 | 1.0/100 |
| Mean (SD) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | |
| Siemens FVIII Chromogenic on the BCS XP System | Target FVIII level/target AT level (%) | 0.0/15 | 0.0/100 | 0.1/15 | 0.1/100 | 0.2/15 | 0.2/100 | 0.5/15 | 0.5/100 | 1.0/15 | 1.0/100 |
| Mean (SD) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | NI (NI) | |
| AT activity (control) assay, % | |||||||||||
| Biophen AT on BCS XP System for FVIII and FIX | Target FVIII level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 |
| Mean (SD) | 12.8 (1.2) | 96.1 (3.9) | 13.5 (1.6) | 92.7 (1.1) | 12.0 (0.8) | 91.7 (3.7) | 13.5 (0.6) | 93.9 (1.3) | 14.0 (0.2) | 90.6 (2.9) | |
| Target FIX level/target AT level (%) | 0/15 | 0 /100 | 5/15 | 5/100 | 20/15 | 20/100 | 50/15 | 50/100 | 100/15 | 100/100 | |
| Mean (SD) | 12.3 (1.6) | 89.8 (1.4) | 13.2 (1.0) | 87.5 (0.7) | 12.0 (1.8) | 92.6 (2.3) | 11.9 (2.3) | 89.3 (0.3) | 12.2 (0.5) | 91.7 (1.5) | |
The target FVIII or FIX levels (at 0%, 5%, 20%, 50%, and 100%) were achieved by mixing ADVATE or BeneFIX, respectively, with factor-deficient plasma. The impact of AT lowering was defined as “none” if there was ±20% variability between the 100% and 15% AT plasma levels. For the control assay, AT was measured at <15% variability. All assays were performed in triplicate.
aPTT, activated partial thromboplastin time; AT, antithrombin; BU, Bethesda Units; FIX/FVIII, factor IX/VIII; NI, no interference; PT, prothrombin time; SD, standard deviation; TT, thrombin time.