Demographics of the study cohort and examination findings*
| Variable | No. (%)† of patients n = 4308 |
|---|---|
| Predictor variables‡ | |
| Median age, yr (IQR) | 83 (75–89) |
| Female | 2770 (64) |
| Clear history of head injury | 2161 (50) |
| Unclear history of head injury | 502 (12) |
| Clear history of loss of consciousness | 325 (8) |
| Unclear history of loss of consciousness | 852 (20) |
| Clear history of new amnesia about events of fall | 611 (14) |
| Unclear history of amnesia | 697 (16) |
| History of previous major bleed | 87 (2) |
| Previous stroke or transient ischemic attack | 761 (18) |
| Renal impairment | 832 (19) |
| Cirrhosis | 60 (1) |
| Takes anticoagulation medication | 1119 (26) |
| Warfarin | 203 (5) |
| Rivaroxaban | 223 (5) |
| Apixaban | 544 (13) |
| Dabigatran | 59 (1) |
| Edoxaban | 7 (< 1) |
| Dalteparin | 13 (< 1) |
| Tinzaparin | 2 (< 1) |
| Enoxaparin | 14 (< 1) |
| Fondaparinux | 1 (< 1) |
| Heparin | 4 (< 1) |
| Anticoagulant name not documented | 49 (1) |
| Takes antiplatelet medication | 1567 (36) |
| ASA | 1104 (26) |
| Clopidogrel | 153 (4) |
| Ticagrelor | 1 (< 1) |
| ASA and clopidogrel | 78 (2) |
| ASA and ticagrelor | 3 (< 1) |
| Antiplatelet name not documented | 228 (5) |
| Clinical Frailty Scale score | |
| 1 Very fit | 230 (5) |
| 2 Well | 468 (11) |
| 3 Managing | 894 (21) |
| 4 Very mild frailty | 589 (14) |
| 5 Mildly frail | 711 (17) |
| 6 Moderately frail | 929 (22) |
| 7–8 Severely frail or very severely frail | 457 (11) |
| 9 Terminally ill | 21 (< 1) |
| Not documented | 9 (< 1) |
| Bruise or laceration on the head | 1662 (39) |
| Reduced Glasgow Coma Scale score from baseline | 229 (5) |
| New abnormality on neurologic examination | 237 (6) |
| Median hemoglobin, g/L (IQR) | 124 (112–134) |
| Median platelet count × 109/L (IQR) | 215 (171–264) |
| Other variables | |
| Retrograde amnesia for > 30 min | 134 (3) |
| Vomited | 157 (4) |
| Once | 86 (2) |
| More than once | 71 (2) |
| Diabetes | 1209 (28) |
| Hypertension | 3120 (72) |
| Active cancer | 402 (9) |
| Cognitive impairment | 1316 (31) |
| History of frequent falls | 1100 (26) |
| Congestive heart failure | 510 (12) |
| Living circumstances | |
| Living at home | 2454 (57) |
| Living in a retirement community | 767 (18) |
| Living in a nursing home or long-term care facility | 719 (17) |
| Not documented | 368 (9) |
| Median weight, kg, as documented in chart (IQR) | 70 (59–82) |
| Median Glasgow Coma Scale score at time of physician assessment (IQR) | 15 (15–15) |
| Signs of basal skull fracture | 70 (2) |
| Suspected open or depressed skull fracture | 11 (< 1) |
| Median creatinine, μmol/L (IQR) | 84 (25–111) |
| Median international normalized ratio (IQR) | 1.1 (1.0–1.2) |
| Admitted from emergency department into hospital | 1536 (36) |
Note: ASA = acetylsalicylic acid, IQR = interquartile range.
↵* Summary of missing data: amnesia of event missing for 4 patients, Clinical Frailty Scale score missing for 9, bruise or laceration missing for 6, reduced Glasgow Coma Scale score from baseline missing for 6, new abnormality on neurologic examination missing for 5, hemoglobin missing for 1255, platelet count missing for 1268, retrograde amnesia missing for 11, vomited more than once missing for 5, weight missing for 1555, Glasgow Coma Scale score missing for 6, signs of basal skull fracture missing for 1, creatinine missing for 1277, international normalized ratio missing for 2496.
↵† Unless otherwise specified.
↵‡ These variables were used to derive the decision rule.