Baseline characteristics of the study participants
| Total n=1711 | Rule-out n=1311 | Observation n=334 | Rule-in n=66 | P value | |
| Female sex, n (%) | 816 (47.7) | 640 (48.8) | 150 (44.9) | 26 (39.4) | 0.177 |
| Age, median (IQR) | 56 (45–68) | 52 (42–62) | 72 (62–83) | 65 (53–82.3) | <0.001 |
| Risk factors for CVD, n (%) | |||||
| Current/history of smoking | 449 (26.2) | 368 (28.1) | 61 (18.3) | 20 (30.3) | 0.001 |
| Previous coronary artery disease | 317 (18.5) | 165 (12.6) | 135 (40.4) | 17 (25.8) | <0.001 |
| Hypertension | 448 (26.2) | 293 (22.3) | 139 (41.6) | 16 (24.2) | <0.001 |
| Hypercholesterolaemia | 422 (24.7) | 295 (22.5) | 110 (32.9) | 17 (25.8) | <0.001 |
| Other CVD* | 288 (16.8) | 146 (11.1) | 123 (36.8) | 19 (28.8) | <0.001 |
| Diabetes mellitus | 171 (10.0) | 106 (8.1) | 55 (16.5) | 10 (15.2) | <0.001 |
| COPD | 80 (4.7) | 38 (2.9) | 37 (11.1) | 5 (7.6) | <0.001 |
| Family history of CVD | 690 (40.3) | 564 (43.0) | 101 (30.2) | 25 (37.9) | <0.001 |
| Presenting acute symptoms, n (%) | |||||
| Chest pain | 1485 (86.8) | 1174 (89.5) | 252 (75.4) | 59 (89.4) | <0.001 |
| Constricting | 1239 (72.4) | 978 (74.6) | 206 (61.7) | 55 (83.3) | <0.001 |
| Sharp | 404 (23.6) | 339 (25.9) | 57 (17.1) | 8 (12.1) | <0.001 |
| Tearing | 64 (3.7) | 54 (4.1) | 7 (2.1) | 3 (4.5) | 0.157 |
| Burning | 208 (12.2) | 166 (12.7) | 32 (9.6) | 10 (15.2) | 0.226 |
| Respiratory dependent | 302 (17.7) | 250 (19.1) | 41 (12.3) | 11 (16.7) | 0.014 |
| Chest-wall tenderness | 205 (12.0) | 170 (13.0) | 33 (9.9) | 2 (3.0) | 0.022 |
| Movement dependent | 219 (12.8) | 183 (14.0) | 35 (10.5) | 1 (1.5) | 0.005 |
| Other pain (abdomen, back or neck) | 48 (2.8) | 32 (2.4) | 14 (4.2) | 2 (3.0) | 0.175 |
| No pain | 177 (10.3) | 104 (7.9) | 68 (20.4) | 5 (7.6) | <0.001 |
| Pain radiation | 1000 (58.4) | 802 (61.2) | 154 (46.1) | 44 (66.7) | <0.001 |
| Dyspnoea | 901 (52.7) | 689 (52.6) | 178 (53.3) | 34 (51.5) | 0.962 |
| Palpitations | 637 (37.2) | 501 (38.2) | 117 (35.0) | 19 (28.8) | 0.195 |
| Syncope/presyncope | 460 (26.9) | 353 (26.9) | 88 (26.3) | 19 (28.8) | 0.917 |
| Acute fatigue | 571 (33.4) | 432 (33.0) | 110 (32.9) | 29 (43.9) | 0.187 |
| Nausea and/or vomiting | 732 (42.8) | 578 (44.1) | 123 (36.8) | 31 (47.0) | 0.043 |
| Diaphoresis | 561 (32.8) | 448 (34.2) | 93 (27.8) | 20 (30.3) | 0.081 |
| First ECG, n (%) | |||||
| Non-ischaemic | 1515 (88.5) | 1187 (90.5) | 282 (84.4) | 46 (69.7) | <0.001 |
| Non-specific changes† | 196 (11.5) | 124 (9.5) | 52 (15.6) | 20 (30.3) | <0.001 |
| Symptom onset to first hs-cTnT (hours), n (%) | |||||
| <3 | 182 (10.6) | 150 (11.4) | 25 (7.5) | 7 (10.6) | 0.109 |
| 3.0–5.99 | 609 (35.6) | 474 (36.2) | 114 (34.1) | 21 (31.8)) | 0.637 |
| 6.0–11.99 | 409 (23.9) | 287 (21.9) | 100 (29.9) | 22 (33.3) | 0.002 |
| 12.0–23.99 | 224 (13.1) | 177 (13.5) | 35 (10.5) | 12 (18.2) | 0.159 |
| >24 | 287 (16.8) | 223 (17.0) | 60 (18.0) | 4 (6.1) | 0.054 |
All values are presented as n (%) and median (IQR). P values are for comparisons across the three triage groups using the Pearson χ2 test or the Fisher exact test for categorical variables, and the Kruskal-Wallis test for continuous variables.
The median time interval between the hs-cTnT samplings of 0 and 1 hour was 65 min (IQR 60–70) with no difference across the groups.
*Includes atrial fibrillation, other arrhythmias, cardiomyopathies, cerebral stroke, heart failure or valvular disease.
†Non-specific changes in either the ST segment, T inversions, Q waves, atrial fibrillation or left/right bundle branch block of unknown clinical significance.
COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; hs-cTnT, high-sensitivity cardiac troponin T.