Comparison between base models and models with propensity score
Model | Key Variables Included/Excluded | LR χ2 (df) | Comparison | Difference in LR χ2 (df ) | P > χ2 | Significant Key Variables | Inference |
---|---|---|---|---|---|---|---|
1 | ACEI/ARB, diabetes, CHF, and hypertension | 184.4894 (df = 11) | – | – | – | ACEI/ARB, diabetes, and CHF | – |
2 | ACEI/ARB, diabetes, CHF, hypertension, and propensity score | 184.7427 (df = 12) | 2 versus 1 | 0.2533 (df = 1) | 0.61480 | ACEI/ARB | Possible high collinearity between propensity score and diabetes, CHF, and hypertension because diabetes and CHF are significant in the base model. Addition of all four variables (diabetes, CHF, hypertension, and propensity score) adds no value to the model. |
3 | ACEI/ARB and propensity score (excludes diabetes, CHF, and hypertension) | 180.9792 (df = 9) | 2 versus 3 | 3.7635 (df = 3) | 0.05238 | ACEI/ARB and propensity score | Confirms high collinearity between propensity score and diabetes, CHF, and hypertension. Addition of diabetes, CHF, and hypertension adds no value to the model when propensity score is already present. Supports the notion that propensity score may be used as a proxy for a disease index for these diseases. |
4 | Diabetes, CHF, hypertension, and propensity score (excludes ACEI/ARB) | 179.2128 (df = 11) | 2 versus 4 | 5.5299 (df = 1) | 0.01869 | None | ACEI/ARB has independent effect on AKI. Addition of ACEI/ARB significantly contributes to the model. |
5 | Propensity score (excludes ACEI/ARB, diabetes, CHF, and baseline hypertension) | 175.4759 (df = 8) | 3 versus 5 | 5.5033 (df = 1) | 0.01898 | Propensity score | ACEI/ARB has independent effect on AKI. Addition of ACEI/ARB significantly contributes to the model. |
4 versus 5 | 3.7369 (df = 3) | 0.05322 | Confirms high collinearity between propensity score and diabetes, CHF, and hypertension. Addition of diabetes, CHF, and baseline hypertension adds no value to the model when propensity score is already present. Supports the notion that propensity score may be used as a proxy for a disease index for these diseases. | ||||
6 | Diabetes, CHF, hypertension (excludes ACEI/ARB and propensity score) | 178.7873 (df = 10) | 1 versus 6 | 5.7021 (df = 1) | Diabetes, CHF, and hypertension | ACEI/ARB has independent effect on AKI. |