Association between predictors and occurrence of serious adverse events
| Predictor* | Outcome; no. (%) or mean ± SD | p value | κ value† | |
|---|---|---|---|---|
| Serious adverse event n = 147 | No serious adverse event n = 3883 | |||
| Demographic | ||||
| Age, yr | 71.6 ± 16.7 | 52.9 ± 23.0 | < 0.001 | – |
| Female sex | 63 (42.9) | 2175 (56.0) | 0.002 | – |
| Medical history | ||||
| Vascular disease‡ (n = 147; 3876) | 16 (10.9) | 238 (6.1) | 0.02 | 0.85 |
| Heart disease§ (n = 138; 3639) | 83 (60.1) | 748 (20.6) | < 0.001 | 0.95 |
| Event details | ||||
| Predisposition to vasovagal syncope¶ (n = 147; 3820) | 19 (12.9) | 1642 (43.0) | < 0.001 | 0.48 |
| Presence of prodrome** (n = 144; 3817) | 82 (56.9) | 2903 (76.1) | < 0.001 | 0.57 |
| Vital sign in emergency department | ||||
| Triage systolic BP (n = 142; 3769) | 133.3 ± 33.0 | 125.3 ± 21.4 | 0.005 | – |
| Highest systolic BP (n = 147; 3853) | 149.1 ± 29.5 | 137.1 ± 22.1 | < 0.001 | – |
| Lowest diastolic BP (n = 146; 3851) | 61.6 ± 17.3 | 65.3 ± 12.8 | 0.01 | – |
| Highest diastolic BP (n = 147; 3850) | 83.6 ± 17.6 | 80.4 ± 13.6 | 0.03 | – |
| Highest heart rate (n = 147; 3851) | 87.2 ± 19.7 | 84 ± 16.6 | 0.05 | – |
| Triage respiratory rate (n = 119; 3099) | 18.0 ± 3.8 | 17.2 ± 2.6 | 0.04 | – |
| Laboratory value | ||||
| Elevated troponin (> 99th percentile of normal population) | 37 (25.2) | 132 (3.4) | < 0.001 | – |
| Hematocrit (n = 145; 3225) | 0.38 ± 0.06 | 0.40 ± 0.05 | < 0.001 | – |
| Serum urea, mmol/L (n = 134; 2939) | 8.8 ± 6.8 | 6.4 ± 4.4 | < 0.001 | – |
| Serum creatinine, μmol/L (n = 145; 3157) | 109.5 ± 68.2 | 88.4 ± 66.0 | < 0.001 | – |
| ECG evidence (n = 143; 3691) | ||||
| Left bundle branch block | 15 (11.4) | 85 (2.3) | < 0.001 | 0.88 |
| Left ventricular hypertrophy | 13 (9.9) | 199 (5.5) | 0.03 | 0.83 |
| QRS duration, ms | 111.1 ± 31.7 | 93.0 ± 17.6 | < 0.001 | – |
| QRS axis, degrees | 16.0 ± 60.4 | 35.6 ± 42.3 | < 0.001 | – |
| Corrected QT interval, ms | 463.6 ± 43.3 | 431.7 ± 30.7 | < 0.001 | – |
| Diagnosis in emergency department | ||||
| Vasovagal syncope | 19 (13.0) | 2165 (55.8) | < 0.001 | 0.60 |
| Cardiac syncope | 51 (34.9) | 194 (5.0) | < 0.001 | 0.60 |
| Categorization of continuous predictors | ||||
| Age > 75 yr | 72 (49.0) | 871 (22.4) | < 0.001 | – |
| Any systolic BP < 90 or > 180 mm Hg†† (n = 147; 3871) | 46 (31.3) | 446 (11.5) | < 0.001 | – |
| Lowest diastolic BP < 50 mm Hg | 30 (20.6) | 348 (9.0) | < 0.001 | – |
| Highest diastolic BP > 110 mm Hg | 12 (8.2) | 90 (2.3) | < 0.001 | – |
| Highest heart rate > 110 beats/min | 18 (12.2) | 244 (6.3) | 0.004 | – |
| Triage respiratory rate > 20 breaths/min | 12 (10.1) | 109 (3.5) | < 0.001 | – |
| Hematocrit < 0.3 | 13 (9.0) | 113 (3.5) | < 0.001 | – |
| Urea > 12 mmol/L | 21 (15.7) | 164 (5.6) | < 0.001 | – |
| Creatinine > 150 μmol/L | 17 (11.7) | 170 (5.4) | 0.001 | – |
| QRS duration > 130 ms | 42 (31.6) | 186 (5.1) | < 0.001 | – |
| Abnormal QRS axis (< −30° or > 110°) | 43 (32.3) | 307 (8.3) | < 0.001 | – |
| Corrected QT interval > 480 ms | 51 (38.4) | 236 (6.4) | < 0.001 | – |
Note: BP = blood pressure, ECG = electrocardiogram.
↵* Numbers within brackets indicate the number of patients in each group for whom data were available for the variable. Where numbers are not reported, the data were available for all of the patients.
↵† Interobserver assessments were conducted for data from 190 (4.7%) of the 4030 patients.
↵‡ Includes transient ischemic attack, cerebrovascular accident and peripheral vascular disease.
↵§ Includes coronary or valvular heart disease, cardiomyopathy, congestive heart failure and non-sinus rhythm (ECG evidence during index visit or documented history of ventricular or atrial arrhythmias, or device implantation).
↵¶ Triggered by being in a warm crowded place, prolonged standing, fear, emotion or pain.
↵** Dizziness, light-headedness, vision changes, nausea or vomiting.
↵†† Includes BP values from triage until disposition from emergency department.