Table 3.
Diagnostic test performance of PIERS-ML risk strata
| PIERS-ML output (for outcomes within 2 days) | Hypertensive pregnant women in stratum | Hypertensive pregnant women with an outcome within 2 days | Hypertensive pregnant women within risk stratum with an outcome within 7 days | Hypertensive pregnant women within risk stratum with an outcome at any time | |
|---|---|---|---|---|---|
| Primary combined adverse maternal outcome (AUROC 0·80 [0·76–0·84], AUPRC 0·38) | |||||
| Very low risk | ≤0·5% | 8 (0·7%) | 0 | 1 (12·5%) | 1 (12·5%) |
| Low risk | 0·6–3·0% | 321 (29·1%) | 7 (2·2%) | 13 (4·0%) | 21 (6·5%) |
| Moderate risk | 3·1–18·6% | 676 (61·3%) | 36 (5·3%) | 58 (8·6%) | 76 (11·2%) |
| High risk | 18·7–45·5% | 87 (7·9%) | 23 (26·4%) | 25 (28·7%) | 28 (32·2%) |
| Very high risk | ≥45·6% | 11 (1·0%) | 10 (90·9%) | 10 (90·9%) | 10 (90·9%) |
| Excluding mean platelet volume (AUROC 0·80 [0·76–0·84], AUPRC 0·39) | |||||
| Very low risk | ≤0·5% | 8 (0·7%) | 0 | 1 (12·5%) | 1 (12·5%) |
| Low risk | 0·6–3·0% | 340 (30·8%) | 8 (2·4%) | 14 (4·1%) | 22 (6·5%) |
| Moderate risk | 3·1–18·6% | 656 (59·5%) | 35 (5·3%) | 56 (8·5%) | 74 (11·3%) |
| High risk | 18·7–45·5% | 86 (7·8%) | 22 (25·6%) | 25 (29·1%) | 28 (32·6%) |
| Very high risk | ≥45·6% | 13 (1·2%) | 11 (84·6%) | 11 (84·6%) | 11 (84·6%) |
| Including fibrinogen and activated prothrombin time (AUROC 0·80 [0·76–0·84], AUPRC 0·38) | |||||
| Very low risk | ≤0·5% | 7 (0·6%) | 0 | 1 (14·3%) | 1 (14·3%) |
| Low risk | 0·6–3·0% | 291 (26·4%) | 6 (2·1%) | 12 (4·1%) | 20 (6·9%) |
| Moderate risk | 3·1–18·6% | 709 (64·3%) | 39 (5·5%) | 61 (8·6%) | 79 (11·1%) |
| High risk | 18·7–45·5% | 82 (7·4%) | 19 (23·2%) | 21 (25·6%) | 24 (29·3%) |
| Very high risk | ≥45·6% | 14 (1·3%) | 12 (85·7%) | 12 (85·7%) | 12 (85·7%) |
| fullPIERS (AUROC 0·62 [0·56–0·68], AUPRC 0·33) | |||||
| Very low risk | ≤1·3% | 6 (0·5) | 2 (33·3%) | 2 (33·3%) | 2 (33·3%) |
| Low risk | NA | NA | NA | NA | NA |
| Moderate risk | 1·4–30·4% | 1011 (91·5%) | 51 (5·0%) | 78 (7·7%) | 105 (10·74) |
| High risk | 30·5–70·6% | 62 (5·6%) | 11 (17·7%) | 14 (22·6%) | 14 (22·6%) |
| Very high risk | ≥70·7% | 26 (2·4%) | 12 (46·2%) | 13 (46·2%) | 15 (57·7%) |
| fullPIERS using PIERS-ML thresholds (AUROC 0·62 [0·56–0·68], AUPRC 0·33) | |||||
| Very low risk | ≤0·5% | 3 (0·3%) | 0 | 0 | 0 |
| Low risk | 0·6–3·0% | 31 (2·8%) | 4 (12·9%) | 5 (16·1%) | 5 (16·1%) |
| Moderate risk | 3·1–18·6% | 868 (79·0%) | 42 (4·8%) | 66 (7·6%) | 89 (10·3%) |
| High risk | 18·7–45·5% | 146 (13·3%) | 12 (8·2%) | 16 (11·0%) | 19 (13·0%) |
| Very high risk | ≥45·6% | 51 (4·6%) | 18 (35·3%) | 20 (39·2%) | 22 (43·1%) |
| fullPIERS refitted on combined dataset (AUROC 0·67 [0·62–0·72], AUPRC 0·25) | |||||
| Very low risk | ≤1·0% | 1 (0·1%) | 0 | 0 | 0 |
| Low risk | NA | NA | NA | NA | NA |
| Moderate risk | 1·1–15·5% | 1031 (93·3%) | 60 (5·8%) | 87 (8·4%) | 115 (11·2%) |
| High risk | 15·6–44·2% | 64 (5·8%) | 11 (17·2%) | 15 (23·4%) | 16 (25·0%) |
| Very high risk | ≥44·3% | 9 (0·8%) | 5 (55·6%) | 5 (55·6%) | 5 (55·6%) |
| fullPIERS refitted on combined dataset using PIERS-ML thresholds (AUROC 0·67 [0·62–0·72], AUPRC 0·25) | |||||
| Very low risk | ≤0·5% | 0 | NA | NA | NA |
| Low risk | 0·6–3·0% | 108 (9·8%) | 5 (4·6%) | 6 (5·6%) | 13 (12·0%) |
| Moderate risk | 3·1–18·6% | 943 (85·8%) | 57 (6·0%) | 85 (9·0%) | 105 (11·1%) |
| High risk | 18·7–45·5% | 40 (3·6%) | 9 (22·5%) | 11 (27·5%) | 12 (30·0%) |
| Very high risk | ≥45·6% | 8 (0·7%) | 5 (62·5%) | 5 (62·5%) | 5 (62·5%) |
| External validation cohort (AUROC 0·76 [0·71–0·82], AUPRC 0·17) | |||||
| Very low risk | ≤0·5% | 9 (0·3%) | 0 | 0 | 0 |
| Low risk | 0·6–3·0% | 1512 (52·1%) | 17 (1·1) | 22 (1·5) | 34 (2·2) |
| Moderate risk | 3·1–18·6% | 1324 (45·7%) | 47 (3·5) | 55 (4·2) | 65 (4·9) |
| High risk | 18·7–45·5% | 52 (1·8%) | 17 (32·7) | 20 (38·5) | 20 (38·5) |
| Very high risk | ≥45·6% | 3 (0·1%) | 2 (66·7) | 2 (66·7) | 2 (66·7) |
Data are n (%). Risk strata determined by diagnostic test performances for first occurrence of any component of the primary combined adverse maternal outcome within 2 days: very low risk –LR <0·1; low risk –LR 0·1 to 0·2; moderate risk +LR <5·0 and –LR >0·2; high risk +LR 5·0 to 10·0; very high risk +LR >10·0. AUROC=area under the receiver-operator characteristic. AUPRC=area under the precision-recall curve. NA=could not select a probability threshold greater than the very low risk threshold that produced a negative likelihood ratio less than or equal to 0·2, when using predicted probabilities from the fullPIERS model.