Multivariable analysis for patients with a length of hospital stay ≥30 days
| RR (95% CI) | P value | |
| NRF*=0 | 1.00 | |
| NRF=1 | 1.64 (1.41 to 1.91) | <0.001 |
| NRF=2 | 2.00 (1.72 to 2.33) | <0.001 |
| NRF=3 | 2.01 (1.70 to 2.38) | <0.001 |
| Age, years | 1.000 (0.999 to 1.001) | 0.07 |
| Sex, male | 1.03 (0.95 to 1.12) | 0.42 |
| Transferred from other hospitals | 0.98 (0.86 to 1.11) | 0.75 |
| Admission to trauma-specialized hospitals† | 0.99 (0.92 to 1.07) | 0.89 |
| Intubation in the ED | 1.21 (1.10 to 1.34) | <0.001 |
| Medical history | 0.76 | |
| Psychiatric diseases | 1.00 (0.93 to 1.08) | 0.95 |
| COPD | 0.86 (0.32 to 2.30) | 0.76 |
| Chronic heart failure | 0.66 (0.21 to 2.06) | 0.47 |
| Cerebrovascular diseases | 1.03 (0.75 to 1.42) | 0.86 |
| CKD on HD | 0.93 (0.35 to 2.49) | 0.88 |
| Vital signs in the ED | ||
| Systolic BP | 0.999 (0.998 to 0.9997) | 0.03 |
| Respiratory rate | 0.999 (0.99 to 1.004) | 0.68 |
| Heart rate | 1.002 (1.00 to 1.004) | 0.03 |
| Body temperature | 0.99 (0.95 to 1.02) | 0.45 |
| GCS score | 0.998 (0.99 to 1.01) | 0.81 |
| ISS | 1.007 (1.00 to 1.01) | <0.001 |
| Admission to non-ICU wards | 0.91 (0.80 to 1.04) | 0.15 |
*NRF ranges from 0 to 3.
†Trauma-specialized hospitals were defined by the number of severe trauma patients with ISS ≥16 registered in the JTDB since January 1, 2004, for each participating hospital. Hospitals with the number of trauma patients in the top half of all participating hospitals were defined as trauma-specialized hospitals.
BP, blood pressure; CKD, chronic kidney dysfunction; COPD, chronic obstructive pulmonary disease; ED, emergency department; GCS, Glasgow Coma Scale; HD, hemodialysis; ICU, intensive care unit; ISS, Injury Severity Score; JTDB, Japan Trauma Databank; NRF, number of regions with fractures in the spine, pelvis, and lower extremity; RR, risk ratio.