Table 2.
Difference-in-Difference Results Showing Changes in Gabapentin Prescribing After Implementing Regulation for Schedule V and PDMP Cohorts. Difference Values Based on Raw Gabapentin Prescribing Data 2013–2018, and DID Estimates Comparing Control and Intervention Groups After Accounting for Covariates
| Schedule V regulation cohort | Control states (n = 10) |
States exposed to policy (n = 3) |
Difference-in-differences estimate | |||||
|---|---|---|---|---|---|---|---|---|
| 2013 | 2018 | Difference | 2013 | 2018 | Difference | Estimate | 95% CI | |
| Total days per enrollee | 24.23 | 34.74 | 10.51 | 30.30 | 36.34 | 6.04 | − 8.37 | − 10.34 to − 6.39 |
| Claims per enrollee | 0.66 | 0.85 | 0.19 | 0.84 | 1.00 | 0.16 | − 0.10 | − 0.15 to − 0.05 |
| Total days per claim | 36.75 | 40.90 | 4.15 | 36.19 | 36.36 | 0.17 | − 4.85 | − 5.95 to − 3.74 |
| PDMP regulation cohort |
Control states (n = 39) |
States exposed to policy (n = 9) |
Difference-in-differences estimate | |||||
| 2013 | 2018 | Difference | 2013 | 2018 | Difference | Estimate | 95% CI | |
| Total days per enrollee | 19.07 | 27.38 | 8.31 | 18.94 | 26.84 | 7.90 | − 1.01 | − 1.74 to − 0.29 |
| Claims per enrollee | 0.51 | 0.65 | 0.14 | 0.51 | 0.66 | 0.15 | − 0.014 | − 0.03 to 0.006 |
| Total days per claim | 37.73 | 42.43 | 4.70 | 37.22 | 40.56 | 3.34 | − 0.89 | − 1.57 to − 0.20 |