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Table 1 Priority dispatch and NACA score

From: Prehospital triage accuracy in a criteria based dispatch centre

Missions Total [n (%)] P1 [n (%)] P2 [n (%)] P3 [n (%)] Correct correlation [n (%)]
NACA 0 332 (1.2) 184 (55.4) 128 (38.6) 20 (6.0) 148 (44.6)
NACA 1 1’247 (4.5) 830 (66.5) 371 (29.8) 46 (3.7) 417 (33.4)
NACA 2 7’122 (25.6) 4’285 (60.2) 2’228 (31.3) 609 (8.5) 2’837 (39.8)
NACA 3 15’208 (54.5) 7’034 (46.2) 5’290 (34.8) 2’884 (19.0) 8’174 (53.7)
NACA 4 2’480 (8.9) 2’034 (82.0) 376 (15.2) 70 (2.8) 2’034 (82.0)
NACA 5 867 (3.1) 767 (88.5) 79 (9.1) 21 (2.4) 767 (88.5)
NACA 6 203 (0.7) 196 (96.5) 5 (2.5) 2 (1.0) 196 (96.6)
NACA 7 427 (1.5) 419 (98.1) 7 (1.7) 1 (0.2) 419 (98.1)
Total 27’886 (100) 15’749 (56.5) 8’484 (30.4) 3’653 (13.1) 14’992 (53.8)
  1. OVER TRIAGE = P1 dispatch with NACA <4 (false positive) / all P1 dispatch (false positive + true positive) = 12’333/15’749 = 78 %
  2. UNDER TRIAGE = P2 or P3 dispatch with NACA >3 (false negative) / all P2 or P3 dispatch (false negative + true negative) = 561/12’137 = 4.6 %
  3. Sensitivity was calculated as true positives/(true positives + false negatives); specificity, as true negatives/(false positives + true negatives)
  4. Positive predictive value (PPV) was calculated as true positives/(true positives + false positives); negative predictive value (NPV), as true negatives/(true negatives + false negatives)
  5. Sensibility = TP / (TP + FN) = 86 % = 95 % CI (85.6–86.4)
  6. Specificity = FN / (FN + FP) = 48 % = 95 % CI (47.4–48.6)
  7. PPV = TP/(TP + FP) = 21.7 % = 95%CI (21.2–22.2)
  8. NPV = TN/(TN + FN) = 95.4 % = 95 % CI (95.2–95.6)