| Pilot | Comparison | Difference (95% CI) | P value, logistic part | P value, negative binomial part | |
|---|---|---|---|---|---|
| Hospitalizations, all-cause | Rate per 1000 patients per month (95% CI)* | ||||
| Pre-intervention | 7.0 | 7.0 | NA** | NA | NA |
| Intervention year 1 | 7.3 | 8.8 | −1.5 (−3.1, 0.2) | 0.056 | 0.40 |
| Intervention year 2 | 7.4 | 9.2 | −1.8 (−3.3, −0.2) | <0.001 | 0.070 |
| Intervention year 3 | 8.5 | 10.2 | −1.7 (−3.2, −0.03) | 0.075 | 0.37 |
| Hospitalizations, ambulatory care-sensitive | |||||
| Pre-intervention | 0.5 | 0.5 | NA | NA | NA |
| Intervention year 1 | 0.5 | 0.7 | −0.2 (−0.6, 0.2) | 0.174 | 0.41 |
| Intervention year 2 | 0.8 | 0.9 | −0.1 (−0.5, 0.4) | 0.46 | 0.081 |
| Intervention year 3 | 0.8 | 1.0 | −0.2 (−0.6, 0.3) | 0.28 | 0.50 |
| ED visits, all-cause | |||||
| Pre-intervention | 23.9 | 23.9 | NA | NA | NA |
| Intervention year 1 | 24.5 | 27.5 | −3.0 (−6.6, 0.5) | 0.55 | 0.028 |
| Intervention year 2 | 26.3 | 28.4 | −2.1 (−5.6, 1.1) | 0.074 | 0.92 |
| Intervention year 3 | 29.5 | 34.2 | −4.7 (−8.7, −0.9) | 0.27 | 0.005 |
| ED visits, ambulatory care-sensitive | |||||
| Pre-intervention | 13.5 | 13.5 | NA | NA | NA |
| Intervention year 1 | 13.5 | 15.0 | −1.4 (−3.8, 1.1) | 0.60 | 0.31 |
| Intervention year 2 | 14.5 | 15.6 | −1.2 (−3.8, 1.3) | 0.146 | 0.70 |
| Intervention year 3 | 16.2 | 19.4 | −3.2 (−5.7, −0.9) | 0.092 | 0.111 |
| Ambulatory visits, primary care | Rate per 1000 patients per month (95% CI)* | ||||
| Pre-intervention | 379.6 | 379.6 | NA** | NA | NA |
| Intervention year 1 | 357.0 | 304.2 | 52.8 (9.1, 99.4) | NA*** | 0.024 |
| Intervention year 2 | 357.1 | 250.0 | 107 (51.1, 178.5) | NA | 0.002 |
| Intervention year 3 | 349.0 | 271.5 | 77.5 (37.3, 120.5) | NA | 0.001 |
| Ambulatory visits, specialist | |||||
| Pre-intervention | 106.2 | 106.2 | NA | NA | NA |
| Intervention year 1 | 108.7 | 117.3 | −8.7 (−16.2, −1.2) | 0.27 | 0.01 |
| Intervention year 2 | 104.8 | 121.3 | −16.5 (−27.5, −5.9) | 0.34 | <0.001 |
| Intervention year 3 | 104.9 | 122.2 | −17.3 (−26.6, −8.0) | 0.23 | <0.001 |
Abbreviations: NA, Not Applicable; CI, confidence interval.
Point estimates for utilization and utilization differences are propensity-weighted recycled predictions from two-part logistic and negative binomial regression models adjusting for baseline utilization rates; patient gender, age, Charlson comorbidity score; health plan contributing each observation, and whether each patient was in an HMO product at the time of the observation. Confidence intervals are bootstrap estimates; p-values are from the regression models.
Due to the inclusion of fixed effects for practices, regression models do not estimate pre-intervention differences between pilot and comparison.
For primary care visits, only one-part negative binomial models converged (because, due to attribution methods, no patients had zero primary care visits in the pre-intervention period).