Table 3.
Regression model results for primary and secondary outcomes using individual-level data (level 2)
| Outcome | Model | COPD admissions in analysis (n) | Change postindex date in comparator sites, estimate (95% CI) | Change postindex date in implementation sites, estimate (95% CI) | Group–time interaction, estimate (95% CI) | P value for interaction term |
| COPD readmission within 28 days | Unadjusted | 19 097 | OR=0.97 (0.84 to 1.11) | OR=0.94 (0.81 to 1.10) | OR=0.97 (0.79 to 1.20) | 0.804 |
| Adjusted* | 18 324 | OR=0.93 (0.81 to 1.07) | OR=0.95 (0.81 to 1.11) | OR=1.02 (0.83 to 1.26) | 0.865 | |
| All-cause readmission within 28 days | Unadjusted | 17 742 | OR=1.02 (0.91 to 1.14) | OR=0.86 (0.76 to 0.98) | OR=0.85 (0.71 to 1.01) | 0.060 |
| Adjusted* | 16 981 | OR=1.00 (0.88 to 1.12) | OR=0.88 (0.77 to 1.00) | OR=0.88 (0.74 to 1.05) | 0.156 | |
| COPD readmission within 90 days† | Unadjusted | 18 381 | IRR=0.99 (0.95 to 1.03) | IRR=0.98 (0.84 to 1.15) | IRR=0.99 (0.84 to 1.16) | 0.899 |
| Adjusted* | 17 634 | IRR=0.98 (0.95 to 1.01) | IRR=0.99 (0.86 to 1.13) | IRR=1.00 (0.87 to 1.16) | 0.971 | |
| Length of stay for COPD admission | Unadjusted | 19 343 | IRR=0.99 (0.94 to 1.04) | IRR=0.93 (0.88 to 0.97) | IRR=0.94 (0.88 to 1.01) | 0.071 |
| Adjusted* | 18 565 | IRR=0.98 (0.94 to 1.03) | IRR=0.93 (0.88 to 0.97) | IRR=0.94 (0.88 to 1.01) | 0.100 | |
| Number of emergency department attendances | Unadjusted | 15 646 | IRR=1.14 (1.04 to 1.26) | IRR=0.63 (0.56 to 0.70) | IRR=0.55 (0.47 to 0.63) | <0.001 |
| Adjusted* | 14 900 | IRR=1.12 (1.02, 1.24) | IRR=0.63 (0.56 to 0.71) | IRR=0.56 (0.48 to 0.65) | <0.001 | |
| In-hospital mortality for COPD admissions | Unadjusted | 19 343 | OR=0.79 (0.64 to 0.98) | OR=0.79 (0.63 to 0.99) | OR=1.00 (0.74 to 1.36) | 0.992 |
| Adjusted* | 18 565 | OR=0.78 (0.63 to 0.97) | OR=0.82 (0.65 to 1.03) | OR=1.05 (0.77 to 1.44) | 0.741 | |
| 90-day mortality† | Unadjusted | 17 664 | IRR=0.93 (0.78 to 1.10) | IRR=0.89 (0.73 to 1.08) | IRR=0.96 (0.74 to 1.24) | 0.734 |
| Adjusted | 16 944 | IRR=0.93 (0.80 to 1.08) | IRR=0.93 (0.79 to 1.11) | IRR=1.01 (0.80 to 1.26) | 0.946 |
*Adjusted for age, sex, ethnicity and IMD quintile.
†CI calculated using robust SEs; the Wald test was used to generate the p value for interaction.
COPD, chronic obstructive pulmonary disease; IMD, Index of Multiple Deprivation; IRR, incidence rate ratio.