Table 1.
Frequency of abnormal patterns of APTT second-derivative curves.
| Normal | Early | Late | Biphasic | |
|---|---|---|---|---|
| Normal | 100% (n = 20) | 0% (n = 0) | 0% (n = 0) | 0% (n = 0) |
| DIC | 100% (n = 11) | 0% (n = 0) | 0% (n = 0) | 0% (n = 0) |
| Warfarin | 95% (n = 19) | 0% (n = 0) | 0% (n = 0) | 5% (n = 1) |
| Heparin | 100% (n = 20) | 0% (n = 0) | 0% (n = 0) | 0% (n = 0) |
| LA | 0% (n = 0) | 100% (n = 2) | 0% (n = 0) | 0% (n = 0) |
| Factor deficiency | 72% (n = 5) | 14% (n = 1) | 0% (n = 0) | 14% (n = 1) |
| COVID-19 (All) | 51% (n = 70) | 5% (n = 7) | 21% (n = 29) | 23% (n = 31) |
| COVID-19 (D-dimer) | 58% (n = 15) | 4% (n = 1) | 15% (n = 4) | 23% (n = 6) |
| COVID-19 (CRP) | 27% (n = 7) | 4% (n = 1) | 31% (n = 8) | 38% (n = 10) |
| COVID-19 (1st visit) | 35% (n = 9) | 4% (n = 1) | 27% (n = 7) | 35% (n = 9) |
χ2 < 0.01 for all the analytical models when all the APTT tests were analyzed together, when only the APTT tests performed at a time point corresponding to the maximum D-dimer or CRP level were analyzed, or when only the APPT tests performed at the time of each subject’s initial visit to the hospital first were analyzed.