Table 4:

Robustness Checks, DD-RD Estimates for Number of Drugs Prescribed or Continued During Physician Visits With Placebo Cut-off, NAMCS 2002–2004 and 2006–2009

	Age 63–66	Age 62–67		Age 61–68	Age 60–69		Age 59–70	Age 58–71
	(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
Number of Drugs Prescribed or Continued
Age 64 * Year 2006	−0.141	−0.418	−0.310	−0.541	−0.302	−0.719*	−0.341	−0.550
	(0.301)	(0.344)	(0.406)	(0.363)	(0.332)	(0.393)	(0.373)	(0.349)
R-squared	0.043	0.041	0.042	0.041	0.040	0.041	0.041	0.042
Age 64 * Year 2006	−0.233	−0.440	−0.407	−0.536	−0.423	−0.665*	−0.450	−0.609*
	(0.272)	(0.321)	(0.382)	(0.346)	(0.314)	(0.376)	(0.358)	(0.329)
R-squared	0.216	0.210	0.210	0.207	0.204	0.204	0.201	0.198
Order of Polynomial	1	2	3	3	3	4	4	4
Number of Drugs with a Generic Equivalent Prescribed or Continued
Age 64 * Year 2006	−0.064	−0.163	−0.054	−0.150	−0.159	−0.170	−0.156	−0.209
	(0.146)	(0.167)	(0.213)	(0.189)	(0.157)	(0.203)	(0.181)	(0.168)
R-squared	0.052	0.052	0.053	0.055	0.054	0.054	0.055	0.058
Age 64 * Year 2006	−0.084	−0.149	−0.082	−0.133	−0.187	−0.130	−0.166	−0.220
	(0.139)	(0.162)	(0.206)	(0.183)	(0.154)	(0.202)	(0.178)	(0.164)
R-squared	0.164	0.163	0.164	0.164	0.161	0.161	0.158	0.158
Order of Polynomial	1	2	3	3	3	4	4	4
Observation	10,538	15,772	15,772	21,072	26,474	26,474	31,898	37,400

^1.Control variables for regressions include a dummy for year 2006 or later, age 65 or over, a polynomial control for age in days and full interaction with the age 65 dummy and year2006 dummy, patient sex, race, Charlson index dummies, disease category by primary diagnosis codes, visit quarter, physician specialty type, whether it is a solo practice or not, electronic medical records utilization, metropolitan statistical area (MSA) status and dummy for revenue from Medicare patients above median.

^2.***Significant at the 1% level (two-tail test); ** Significant at the 5% level (two-tail test); * Significant at the 10% level (two-tail test).