| Cohort; no. (%) of patients* | |||
|---|---|---|---|
| Characteristic | Derivation n = 830 | Validation n = 552 | p value† |
| Demographic | |||
| Age, yr, mean ± SD | 53.3 ± 16.2 | 51.3 ± 17.4 | 0.03 |
| No. aged ≥ 65 yr | 210 (25.3) | 131 (23.7) | 0.5 |
| Sex, male | 522 (62.9) | 346 (62.7) | 0.9 |
| Clinical | |||
| Pleuritic chest pain | 437 (52.6) | 295 (53.4) | 0.2 |
| Dyspnea at rest | 55 (6.6) | 36 (6.5) | 0.9 |
| Dyspnea | 177 (21.3) | 121 (21.9) | 0.8 |
| Hemoptysis | 6 (0.7) | 5 (0.9) | 0.8** |
| Mechanism of injury‡ | |||
| Simple fall | 294 (35.9) | 188 (34.5) | 0.6 |
| Fall above ground level | 184 (22.5) | 129 (23.7) | 0.6 |
| Motor vehicle crash | 200 (24.4) | 139 (25.5) | 0.6 |
| Cyclist v. car | 5 (0.6) | 5 (0.9) | 0.5 |
| Direct hit | 85 (10.4) | 57 (10.4) | > 0.9 |
| Other | 51 (6.2) | 27 (5.0) | 0.3 |
| Pre-existing comorbidity | |||
| COPD | 34 (4.1) | 11 (2.0) | 0.03 |
| Asthma | 77 (9.3) | 35 (6.3) | 0.05 |
| Osteoporosis | 60 (7.2) | 40 (7.2) | > 0.9 |
| Diabetes mellitus | 85 (10.2) | 48 (8.7) | 0.3 |
| ≥ 1 pre-existing comorbidity | 213 (25.7) | 119 (21.6) | 0.09 |
| Smoking status§ | |||
| Former smoker | 179 (25.0) | 117 (25.7) | 0.9 |
| Current smoker | 219 (30.6) | 134 (29.5) | 0.6 |
| Never smoker | 318 (44.4) | 204 (44.8) | 0.9 |
| Alcohol intoxication | 56 (6.7) | 36 (6.5) | 0.9 |
| Cohort; no. (%) of patients* | |||
| Characteristic | Derivation n = 830 | Validation n = 552 | p value† |
| Pre-injury antiplatelet/anticoagulant medication | |||
| ASA | 138 (16.6) | 90 (16.3) | 0.9 |
| Clopidogrel | 14 (1.7) | 7 (1.3) | 0.5 |
| Warfarin | 32 (3.9) | 19 (3.4) | 0.7 |
| Any | 171 (20.6) | 106 (19.2) | 0.5 |
| Results of physical examination in emergency department | |||
| Chest abrasion | 36 (4.3) | 29 (5.3) | 0.4 |
| Chest contusion | 154 (18.6) | 95 (17.2) | 0.5 |
| Bone crepitus | 24 (2.9) | 13 (2.4) | 0.5 |
| Other | 213 (25.7) | 139 (25.2) | 0.8 |
| Vital signs, mean ± SD | |||
| Heart rate, beats/min | 81.0 ± 14.1 | 80.6 ± 14.1 | 0.7 |
| Oxygen saturation, % | 97.6 ± 1.9 | 97.9 ± 1.9 | 0.01 |
| Systolic blood pressure, mm Hg | 141.0 ± 21.4 | 139.6 ± 19.6 | 0.2 |
| Diastolic blood pressure, mm Hg | 82.1 ± 12.4 | 81.1 ± 12.5 | 0.1 |
| Respiratory rate, breaths/min | 17.7 ± 3.1 | 17.8 ± 3.5 | 0.9†† |
| No. of rib fractures¶ | |||
| None | 560 (68.5) | 354 (64.8) | 0.2 |
| 1 | 112 (13.7) | 91 (16.7) | 0.1 |
| 2 | 78 (9.5) | 52 (9.5) | > 0.9 |
| ≥ 3 | 68 (8.3) | 49 (9.0) | 0.6 |
| Location of fracture¶ | |||
| Any high rib (3-5) | 59 (7.2) | 47 (8.6) | 0.3 |
| Any mid rib (6-9) | 194 (23.7) | 132 (24.2) | 0.8 |
| Any high or mid rib (3-9) | 221 (27.0) | 159 (29.1) | 0.4 |
| Any low rib (10-12) | 81 (9.9) | 54 (9.9) | > 0.9 |
| Atelectasis† | 84 (10.1) | 45 (8.2) | 0.2 |
Note: ASA = acetylsalicylic acid, COPD = chronic obstructive pulmonary disease, SD = standard deviation.
*Except where indicated otherwise.
†All statistical analyses were performed with the Student t test or χ2 test, except where indicated otherwise.
‡For mechanism of injury, data were available for 819 patients in the derivation group and 545 in the validation group. There were no patients with pedestrian v. car as the mechanism of injury.
§For smoking status, data were available for 716 patients in the derivation group and 455 patients in the validation group.
¶Number and location of fractures were confirmed by initial radiography. For these variables, data were available for 818 patients in the derivation group and 546 in the validation group.
**Fisher exact test.
††Wilcoxon test.