. Author manuscript; available in PMC: 2013 Sep 1.

Published in final edited form as: J Ment Health Policy Econ. 2012 Sep;15(3):105–118.

Appendix Table 2.

The Impact of the Coverage Gap on Medication Use among Elderly Beneficiaries Diagnosed with Depression and Heart Failure Who Entered the Coverage Gap Period in 2007

Panel A. All Medications
		Unadjusted Data		Diff-in-Diff Coverage Gap Effects^†		% Change, Diff-in-Diff Effects/Pre-Gap Values

		Pre-Gap	Within-Gap	Estimate	95% CI	%	95% CI
*Probability of Using any Drug*
All	No-coverage	1.00	0.96	0.00	(−0.005, 0.009)	0.2	(−0.49, 0.88)
All	Generic-only	1.00	0.97	reference

Brand-name	No-coverage	1.00	0.91	0.01	(0.000, 0.019)	0.9	(−0.05, 1.88)
Brand-name	Generic-only	1.00	0.92	reference

Generics	No-coverage	0.99	0.94	0.00	(−0.005, 0.011)	0.3	(−0.53, 1.10)
Generics	Generic-only	1.00	0.96	reference

*No. of Monthly Prescriptions for any Drug*
All	No-coverage	7.08	6.17	−0.03	(−0.141, 0.087)	−0.4	(−1.99, 1.23)
All	Generic-only	7.97	6.81	reference

Brand-name	No-coverage	3.29	2.57	−0.03	(−0.089, 0.028)	−0.9	(−2.71, 0.84)
Brand-name	Generic-only	3.49	2.57	reference

Generics	No-coverage	3.76	3.56	0.01	(−0.070, 0.094)	0.3	(−1.86, 2.51)
Generics	Generic-only	4.43	4.19	reference

*Monthly Pharmacy Spending for any Drug*
All	No-coverage	429	357	−14.54	(−22.730, −6.347)	−3.4	(−5.30, −1.48)
All	Generic-only	468	374	reference

Brand-name	No-coverage	342	277	−8.44	(−15.845, −1.028)	−2.5	(−4.64, −0.30)
Brand-name	Generic-only	364	274	reference

Generics	No-coverage	86	79	−5.80	(−8.738, −2.864)	−6.7	(−10.13, −3.32)
Generics	Generic-only	103	99	reference

Panel B. Antidepressants
		Unadjusted Data		Diff-in-Diff Coverage Gap Effects^†		% Change, Diff-in-Diff Effects/Pre-Gap Values

		Pre-Gap	Within-Gap	Estimate	95% CI	%	95% CI
*Probability of Using an Antidepressant*
All	No-coverage	0.79	0.71	0.00	(−0.018, 0.014)	−0.2	(−2.24, 1.78)
All	Generic-only	0.82	0.74	reference

Brand-name	No-coverage	0.38	0.32	−0.01	(−0.019, 0.009)	−1.4	(−5.14, 2.39)
Brand-name	Generic-only	0.36	0.31	reference

Generics	No-coverage	0.55	0.49	0.00	(−0.013, 0.020)	0.6	(−2.35, 3.56)
Generics	Generic-only	0.59	0.54	reference

*No. of Monthly Prescription for Antidepressants*
All	No-coverage	0.75	0.68	−0.02	(−0.041, 0.006)	−2.3	(−5.43, 0.85)
All	Generic-only	0.84	0.74	reference

Brand-name	No-coverage	0.29	0.25	0.01	(−0.006, 0.021)	2.6	(−2.21, 7.39)
Brand-name	Generic-only	0.30	0.24	reference

Generics	No-coverage	0.46	0.43	−0.02	(−0.045, −0.004)	−5.4	(−9.77, −0.97)
Generics	Generic-only	0.54	0.51	reference

*Monthly Pharmacy Spending for Antidepressants*
All	No-coverage	40	33	0.13	(−1.500, 1.754)	0.3	(−3.76, 4.40)
All	Generic-only	44	35	reference

Brand-name	No-coverage	29	25	0.59	(−0.946, 2.128)	2.1	(−3.29, 7.40)
Brand-name	Generic-only	31	25	reference

Generics	No-coverage	11	8	−0.46	(−1.213, 0.285)	−4.2	(−10.93, 2.56)
Generics	Generic-only	14	11	reference

*Medication Possession Ratio(MPR) for Antidepressants*
All	No-coverage	0.56	0.49	0.00	(−0.015, 0.011)	−0.4	(−2.78, 2.01)
All	Generic-only	0.60	0.53	reference

Panel C. Heart Failure Medications
		Unadjusted Data		Diff-in-Diff Coverage Gap Effects^†		% Change, Diff-in-Diff Effects/Pre-Gap Values

		Pre-Gap	Within-Gap	Estimate	95% CI	%	95% CI
*Probability of Using a Heart Failure Drugs*
All	No-coverage	0.95	0.88	0.02	(0.005, 0.027)	1.7	(0.53, 2.81)
All	Generic-only	0.96	0.89	reference

Brand-name	No-coverage	0.74	0.55	0.02	(0.005, 0.040)	3.0	(0.69, 5.38)
Brand-name	Generic-only	0.74	0.56	reference

Generics	No-coverage	0.89	0.83	0.01	(−0.001, 0.026)	1.4	(−0.06, 2.89)
Generics	Generic-only	0.90	0.85	reference

*No. of Monthly Prescriptions for Heart Failure Drugs*
All	No-coverage	2.44	2.04	−0.02	(−0.072, 0.028)	−0.9	(−2.95, 1.16)
All	Generic-only	2.66	2.23	reference

Brand-name	No-coverage	0.92	0.57	−0.03	(−0.054, −0.001)	−3.0	(−5.87, −0.09)
Brand-name	Generic-only	0.98	0.58	reference

Generics	No-coverage	1.52	1.47	0.01	(−0.036, 0.048)	0.4	(−2.36, 3.13)
Generics	Generic-only	1.68	1.64	reference

*Monthly Pharmacy Spending for Heart Failure Drugs*
All	No-coverage	83	60	−2.72	(−4.826, −0.615)	−3.3	(−5.80, −0.74)
All	Generic-only	90	64	reference

Brand-name	No-coverage	29	25	−2.87	(−4.839, −0.894)	−4.6	(−7.81, −1.44)
Brand-name	Generic-only	31	25	reference

Generics	No-coverage	21	23	0.14	(−0.823, 1.113)	0.7	(−3.88, 5.25)
Generics	Generic-only	24	25	reference

*Medication Possession Ratio(MPR) for Heart Failure Drugs*
All	No-coverage	0.89	0.79	0.00	(−0.009, 0.013)	0.2	(−1.04, 1.44)
All	Generic-only	0.90	0.82	reference

^†

“Gap Effects” are adjusted estimates from the difference model with the inverse of propensity score as a weight. The estimates measure changes in outcomes between within-gap and pre-gap periods in a study group, relative to the changes in outcomes in the other group.

Abbreviations: LIS = low-income-subsidies; this is the comparison group. HF=heart failure.

Bold denotes statistically significant at α = 0.05.