Table 2 Results of the generalized linear mixed model analysis in which patient volume was included as a continuous variable
Population of severe burn patients adjusted by the prognostic burn index | |||||
 Primary outcome | N (%) | Crude odds ratio (95% CI) | p value | Adjusted odds ratio (95% CI) | p value |
  In-hospital mortality | 1287 (24.5) | 1.07 (1.05–1.09) | < 0.001 | 1.14 (1.09–1.19) | < 0.001 |
 Secondary outcomes | Median [IQR] | Crude difference (95% CI) | p value | Adjusted difference (95% CI) | p value |
  Total healthcare costs per admission, USD | 23,628 [7452, 58,458] | 3278 (3043–3512) | < 0.001 | 4876 (4436–5316) | < 0.001 |
  Hospital-free days at 90 days, days | 28 [0, 67] | − 1.6 (− 1.7 to − 1.5) | < 0.001 | − 3.1 (− 3.4 to − 2.8) | < 0.001 |
Population who were directly transported from the scene of injury adjusted by the prognostic burn index | |||||
 Primary outcome | N (%) | Crude odds ratio (95% CI) | p value | Adjusted odds ratio (95% CI) | p value |
  In-hospital mortality | 1017 (27.3) | 1.14 (1.11–1.18) | < 0.001 | 1.22 (1.17–1.30) | < 0.001 |
 Secondary outcomes | Median [IQR] | Crude difference (95% CI) | p value | Adjusted difference (95% CI) | p value |
  Total healthcare costs per admission, USD | 22,723 [7087, 58,753] | 6191 (5703–6678) | < 0.001 | 6755 (6076–7434) | < 0.001 |
  Hospital-free days at 90 days, days | 22 [0, 66] | − 3.0 (− 3.2 to − 2.7) | < 0.001 | − 4.4 (− 4.9 to − 3.9) | < 0.001 |
Population whose prognostic burn index ≤ 120 adjusted by the prognostic burn index | |||||
 Primary outcome | N (%) | Crude odds ratio (95% CI) | p value | Adjusted odds ratio (95% CI) | p value |
  In-hospital mortality | 876 (18.4) | 1.07 (1.05–1.09) | < 0.001 | 1.16 (1.10–1.22) | < 0.001 |
 Secondary outcomes | Median [IQR] | Crude difference (95% CI) | p value | Adjusted difference (95% CI) | p value |
  Total healthcare costs per admission, USD | 25,289 [8356, 59,223] | 3823 (3544–4101) | < 0.001 | 6021 (5501–6541) | < 0.001 |
  Hospital-free days at 90 days, days | 36 [0, 69] | − 1.7 (− 1.9 to − 1.6) | < 0.001 | − 3.5 (− 3.8 to − 3.2) | < 0.001 |
Cohort of severe burn patients who survived for more than 2 days of admission adjusted by the developed risk adjustment model | |||||
 Primary outcome | N (%) | Crude odds ratio (95% CI) | p value | Adjusted odds ratio (95% CI) | p value |
  In-hospital mortality | 956 (19.4) | 1.07 (1.05–1.09) | < 0.001 | 1.04 (0.98–1.10) | 0.174 |
 Secondary outcomes | Median [IQR] | Crude difference (95% CI) | p value | Adjusted difference (95% CI) | p value |
  Total healthcare costs per admission, USD | 26,832 [9224, 62,428] | 3871 (3604–4138) | < 0.001 | 6689 (5892–7487) | < 0.001 |
  Hospital-free days at 90 days, days | 35 [0, 68] | − 1.7 (− 1.8 to − 1.6) | < 0.001 | − 2.1 (− 2.4 to − 1.8) | < 0.001 |