Table 3.
Difference-in-Differences Logistic Regression Results: SIM Impact on 30-Day Hospital Readmissions among Adults with Diabetes
| Model 1 (Difference-in-Difference, Pre-Treatment Trend Adjustment, PS weights) n=3,391,434 |
Model 2 (Difference-in-Difference, no Pre-Treatment Trend Adjustment, PS weights) N=3,391,434 |
Model 3 (Model 1 with Medicare and Medicaid Populations Only) n=2,427,713 |
||||
|---|---|---|---|---|---|---|
| Variable | aOR | 95% CI | aOR | 95% CI | aOR | 95% CI |
| SIM × Post | 1.057** | 1.013, 1.103 | 0.965** | 0.937, 0.994 | 1.057* | 1.001, 1.106 |
| SIM × year trend | 0.970*** | 0.958, 0.983 | 0.970*** | 0.956, 0.983 | ||
| Race/ethnicity | ||||||
| Black | 0.941*** | 0.925, 0.957 | 0.941*** | 0.925, 0.957 | 0.956*** | 0.935, 0.976 |
| Hispanic | 0.885*** | 0.862, 0.907 | 0.884*** | 0.862, 0.907 | 0.901*** | 0.877, 0.926 |
| Other | 0.840*** | 0.814, 0.866 | 0.839*** | 0.814, 0.866 | 0.858*** | 0.826, 0.892 |
| Age | 1.003*** | 1.002, 1.004 | 1.003*** | 1.002, 1.004 | 1.001* | 1.002, 1.004 |
| Female | 0.917*** | 0.906, 0.927 | 0.917*** | 0.906, 0.927 | 0.915*** | 0.904, 0.927 |
| Length of stay | 1.037*** | 1.035, 1.039 | 1.037*** | 1.035, 1.039 | 1.030*** | 1.030, 1.035 |
| ED admission | 1.215*** | 1.190, 1.241 | 1.215*** | 1.190, 1.241 | 1.227*** | 1.198, 1.256 |
| Comorbidity count | 1.140*** | 1.135, 1.145 | 1.140*** | 1.135, 1.145 | 1.136*** | 1.131, 1.141 |
| Payer | ||||||
| Medicaid | 1.051*** | 1.024, 1.078 | 1.051*** | 1.024, 1.078 | ||
| Medicare-Medicaid | 1.107*** | 1.086, 1.128 | 1.108*** | 1.087, 1.129 | ||
| Private | 0.739*** | 0.725, 0.753 | 0.739*** | 0.725, 0.753 | ||
| Uninsured | 0.682*** | 0.644, 0.722 | 0.682*** | 0.644, 0.722 | ||
| Other | 0.816*** | 0.790, 0.842 | 0.816*** | 0.790, 0.843 | ||
| Goodness of Fit | ||||||
| AIC | 1394714 | 1394745 | 1099189 | |||
| BIC | 1395066 | 1395071 | 1099430 | |||
Note: Models 1, 2, and 3 are estimated using four-group propensity score weighting; models include year and hospital indicators (not shown). Standard errors are estimated by clustering at the hospital level. aOR: adjusted odds ratio; for interaction terms, it is the ratio of two adjusted odds ratios. CI=confidence interval. Reference group for race/ethnicity is white and for payer is Medicare. 165 observations were dropped in regression models due to perfect prediction within hospitals.
Source: Authors’ analysis of Healthcare Cost and Utilization Project’s State Inpatient Databases
*
p<0.10
**
p<0.05
***
p<0.01