| Patient characteristic | Unadjusted OR* (95% CI) |
|---|---|
| Age, yr | |
| < 65 | 1.36 (1.27–1.46) |
| 65–74 | 1.22 (1.11–1.33) |
| 75–84 | 1.16 (1.09–1.23) |
| ≥ 85 | 1.15 (1.07–1.23) |
| Sex | |
| Female | 1.35 (1.26–1.45) |
| Male | 1.16 (1.08–1.25) |
| Neighbourhood household income | |
| Highest quintile | 1.27 (1.14–1.42) |
| Next to highest quintile | 1.22 (1.11–1.33) |
| Middle quintile | 1.23 (1.13–1.34) |
| Next to lowest quintile | 1.25 (1.17–1.34) |
| Lowest quintile | 1.28 (1.19–1.37) |
| Charlson Comorbidity Index | |
| ≤ 1 | 1.42 (1.24–1.63) |
| ≥ 2 | 1.17 (1.10–1.24) |
| Admissions to hospital in previous year | |
| 1 | 1.46 (1.35–1.58) |
| ≥ 2 | 1.09 (1.01–1.18) |
| Physician clinic visits in previous year | |
| ≤ 6 | 1.32 (1.21–1.43) |
| ≥ 7 | 1.23 (1.15–1.32) |
| Most responsible diagnosis for readmission to hospital† | |
| Injury | 2.27 (1.72–2.99) |
| Diverticular disease | 2.25 (1.43–3.55) |
| Intestinal obstruction | 1.80 (1.32–2.45) |
| Abdominal pain | 1.61 (0.61–4.23) |
| Skin infection | 1.53 (1.00–2.35) |
| Acute coronary syndrome | 0.93 (0.80–1.07) |
| Venous thromboembolism | 0.89 (0.67–1.19) |
| Chest pain not otherwise specified | 0.75 (0.29–1.90) |
| Syncope and collapse | 0.64 (0.25–1.63) |
| Chronic ischemic heart disease | 0.52 (0.35–0.76) |
| Primary length of stay longer than cohort median | |
| No | 1.26 (1.16–1.36) |
| Yes | 1.25 (1.15–1.35) |
| Hospital-free interval longer than cohort median | |
| No | 1.30 (1.19–1.42) |
| Yes | 1.20 (1.13–1.27) |
| Residence in chronic care facility at readmission | |
| No | 1.25 (1.17–1.33) |
| Yes | 0.99 (0.89–1.11) |
| Arrival by ambulance at readmission | |
| No | 1.19 (1.07–1.31) |
| Yes | 1.02 (0.96–1.08) |
Note: CI = confidence interval, OR = odds ratio. *Calculated for each stratum using unadjusted univariable general estimating equations models. †The 5 diagnostic categories with the greatest effect on the unadjusted risk of 30-day mortality with alternative-hospital readmission and the 5 with the least effect were selected for presentation here. For a full list of unadjusted results stratified by diagnosis at secondary admission, see eTable 10 in Appendix 1.