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Neighbor‑based augmentation (NECA) adds a cumulative curve of when similar patients develop organ problems to a patient’s early‑ICU data, letting standard predictors look beyond the immediate record. The method retrieves up to K training patients whose early‑window profiles match the query and, for each prediction horizon (6 h, 12 h, 24 h, 42 h), counts the fraction of those neighbors that experience the event within that horizon. These fractions become new features that are concatenated with the original representation and fed to any downstream model.

On PhysioNet 2012 the Curve‑NECA model outperformed the raw baseline across all four organ‑dysfunction endpoints. For neurological events the mean PR‑AUC rose from 0.461 to 0.557 and the mean ROC‑AUC from 0.689 to 0.766. Similar gains appeared for renal, electrolyte/metabolic and inflammatory events. The same pattern held on a 4,000‑stay subset of MIMIC‑IV.
| PR-AUC | ROC-AUC | ||||
|---|---|---|---|---|---|
| Dataset | Endpoint | Raw | Curve-NECA | Raw | Curve-NECA |
| PN12 | Neurological | 0.461 | 0.557 | 0.689 | 0.766 |
| Renal | 0.353 | 0.387 | 0.711 | 0.740 | |
| Electrolyte/metabolic | 0.357 | 0.378 | 0.671 | 0.692 | |
| Inflammatory | 0.514 | 0.538 | 0.692 | 0.727 | |
| MIMIC | Neurological | 0.419 | 0.520 | 0.749 | 0.809 |
| Renal | 0.319 | 0.345 | 0.668 | 0.693 | |
| Electrolyte/metabolic | 0.340 | 0.357 | 0.662 | 0.674 | |
| Inflammatory | 0.276 | 0.289 | 0.679 | 0.696 | |
The study used a record‑level split, so records from the same patient could fall in training and test sets, potentially inflating the reported gains. A subject‑disjoint split and cross‑fitted neighbor curves would be needed to confirm the robustness of the improvement.
Figure 1 illustrates the NECA pipeline, while Table 5 presents the quantified superiority of Curve‑NECA over the raw baseline.