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Table 3 Performance of selected comorbidity measures in assessing the association between comorbidity and selected outcome measures (Victoria)

From: Australian Injury Comorbidity Indices (AICIs) to predict burden and readmission among hospital-admitted injury patients

Model LOSa LOSb Hospital costsc
AUC (95% CI) Model fit AIC McFadden’s Adjusted R2 Model fit AIC Adjusted R2 Model fit AIC
(i) Baseline model 0.748 (0.745–0.750) 145,468 0.080 579,331 0.312 304,799
(ii) Baseline model + selected comorbidities (individually modelled with binary representation) 0.760 (0.757–0.763) 142,523 0.088 572,274 0.359 297,352
(iii) Baseline model + selected comorbidities (modelled as a weighted summed score)3 0.760 (0.757–0.762) 142,582 0.088 572,673 0.357 297,674
(iv) Baseline model + comorbidity using CCI weights 0.752 (0.749–0.754) 144,554 0.083 577,080 0.328 302,263
(v) Baseline model + comorbidity using Quan weights 0.752 (0.749–0.754) 144,527 0.082 577,610 0.325 302,663
(vi) Baseline model + ECM 0.761 (0.759–0.764) 142,174 0.089 571,537 0.366 296,207
(vii) Baseline model + 23 comorbidities common to LOS and cost outcomes (binary representation)/Baseline model + 8 comorbidities common to readmission outcomes (binary representation) 0.760 (0.757–0.762) 142,603 0.088 448,263 0.358 297,494
Model All-cause 30-day readmissiond Non-planned 30-day readmissione
AUC (95% CI) Model fit AIC AUC (95% CI) Model fit AIC
(i) Baseline model 0.611 (0.606–0.615) 99,275 0.623 (0.618–0.628) 75,455
(ii) Baseline model + selected comorbidities (individually modelled with binary representation) 0.625 (0.621–0.630) 98,445 0.637 (0.632–0.642) 74,950
(iii) Baseline model + selected comorbidities (modelled as a weighted summed score)f 0.625 (0.620–0.629) 98,473 0.636 (0.631–0.642) 74,946
(iv) Baseline model + comorbidity using CCI weights 0.622 (0.617–0.626) 98,662 0.633 (0.628–0.638) 75,096
(v) Baseline model + comorbidity using Quan weights 0.620 (0.615–0.624) 98,824 0.631 (0.626–0.637) 75,174
(vi) Baseline model + ECM 0.626 (0.622–0.631) 98,457 0.639 (0.634–0.644) 74,912
(vii) Baseline model + 23 comorbidities common to LOS and cost outcomes (binary representation)/Baseline model + 8 comorbidities common to readmission outcomes (binary representation) 0.622 (0.617–0.626) 98,707 0.635 (0.630–0.640) 75,010
  1. Notes
  2. a Baseline model includes age, sex, injury severity, injury type, body region, geographic region, SEIFA deciles and country of birth; outcome = overnight stay discharge (logistic model)
  3. b Baseline model includes age, sex, injury severity, injury type, body region, SEIFA deciles and country of birth; outcome = LOS of non-same day discharges with 1–30 days stay (negative binomial model)
  4. c Baseline model includes age, sex, injury severity, injury type, body region, SEIFA deciles, geographic region (metropolitan and regional) and country of birth; outcome = hospital costs (Ln transformed linear model)
  5. d Baseline model includes age, sex, injury type, body region, geographic region and country of birth; outcome = all cause 30-day readmission (logistic model)
  6. e Baseline model includes age, sex, injury severity, injury type, body region, geographic region and SEIFA deciles; outcome = non-planned 30 day readmission (logistic model)
  7. f See Methods for weight calculation, excludes weights resulting from an OR < 1.2
  8. See Table 4 for selected comorbidities for each outcome
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