Table 3.
Observed Difference-in-Differences in the Primary and Secondary Outcomes of Interest during the Implementation of Medicare Part D
| Outcome Variable | 2005 | 2006 | Differences | DD | t-Value | p-Value |
|---|---|---|---|---|---|---|
| Out-of-pocket costs for prescription drugs | ||||||
| Elderly | 854.33 | 598.88 | −255.45 | −229.05 | −4.49 | <.0001 |
| Near elderly | 461.43 | 435.03 | −26.40 | |||
| Number of prescription refills | ||||||
| Elderly | 21.98 | 23.88 | 1.89 | 1.19 | 1.51 | .1311 |
| Near elderly | 15.43 | 16.13 | 0.70 | |||
| Number of emergency department use | ||||||
| Elderly | 0.1706 | 0.1941 | 0.0235 | 0.0522 | 1.57 | .1181 |
| Near elderly | 0.1302 | 0.1015 | −0.0287 | |||
| Number of hospitalization | ||||||
| Elderly | 0.1407 | 0.1574 | 0.0167 | 0.0257 | 1.15 | .2531 |
| Near elderly | 0.0887 | 0.0797 | −0.0091 | |||
| Preference-based health utility score | ||||||
| Elderly | 0.7798 | 0.7798 | −0.0001 | 0.0008 | −1.18 | .2378 |
| Near elderly | 0.8043 | 0.8034 | −0.0009 | |||
| Prescription drug costs paid by Medicare | ||||||
| Elderly | 127.47 | 831.48 | 704.00 | 704.00 | 8.75 | <.0001 |
| Near elderly | 0.00 | 0.00 | 0.00 | |||
| Prescription drug costs paid by private insurance | ||||||
| Elderly | 446.88 | 146.75 | −300.13 | −351.57 | −5.49 | <.0001 |
| Near elderly | 656.90 | 708.34 | 51.44 | |||
| Total prescription drug costs | ||||||
| Elderly | 1520.17 | 1621.10 | 100.92 | 84.76 | 0.90 | .3704 |
| Near elderly | 1130.56 | 1146.72 | 16.16 | |||
| Total emergency department use costs | ||||||
| Elderly | 82.86 | 90.97 | 8.11 | 4.25 | 0.13 | .8954 |
| Near elderly | 93.22 | 97.08 | 3.86 | |||
| Total hospitalization costs | ||||||
| Elderly | 1723.43 | 1659.18 | −64.25 | −184.34 | −0.34 | .7369 |
| Near elderly | 1125.75 | 1245.84 | 120.09 | |||
| Has usual third-party payer | Round 1 | Round 2 | Round 3 | Round 4 | Round 5 | |
| Elderly | 39.89% | 43.71% | 48.78% | 65.01% | 65.61% | |
| Near elderly | 40.68% | 47.45% | 47.88% | 54.41% | 56.21% | |
| Prescription drugs paid by Medicare (%) | ||||||
| Elderly | 4.25% | 3.74% | 6.50% | 17.40% | 19.32% | |
| Near elderly | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | |
Elderly: Medicare beneficiaries, 65 years or older, excluding those under Medicaid and those with government subsidies as well as those with inconsistent report on drug coverage (N = 556, with 491 for utility score values).
Near elderly: the corresponding respondents with age between 55 and 63 in 2005 (N = 549, with 484 for utility score values).
Source: MEPS Panel 10 longitudinal data file, 2005–2006.