TABLE 3.

Effect of OER Access Restriction on Costs: Difference-in-Difference Analysis

Comparison: Pre- vs. Post-Index Periods
Health Care Charges	Change in PPPM (Patients Remained in Plan in Postindex Period vs. All Patients in the Pre-index Period)			Difference in PPPM Change
	Control Year 2012a	Restriction Year 2013	Control Year 2014a	2013-2012	2014-2013	P Value 2013-2012	P Value 2014-2013
n	762	1,001	832
Total, $	-241	-117	79	124	196	0.461	0.303
Office visits, $	-370	-175	-40	195	135	0.221	0.495
All prescriptions, $	129	58	119	-70	61	0.048	0.072
LAO prescriptions	39	-10	-14	-48	-4	0.001	0.833
Nonopioid prescriptions	87	59	100	-28	41	0.299	0.187
SAO prescriptions	3	9	33	6	24	0.210	< 0.0001
Comparison: Remained vs. Disenrolled Patients
Health Care Charges	Change in PPPM Postrestriction Period (Remained, Disenrolled)			Change in PPPM (Difference in Difference)
	Control Year 2012a	Restriction Year 2013	Control Year 2014a	2013-2012	2014-2013	P Value 2013-2012	P Value 2014-2013
n (remained/disenrolled)	663/99	941/60	726/106
Total, $	11	658	616	646	-42	0.249	0.944
Office visits, $	26	392	448	366	56	0.471	0.916
All prescriptions, $	-14	265	168	280	-98	0.210	0.709
LAO prescriptions	56	144	14	87	-130	0.361	0.163
Nonopioid prescriptions	-83	108	121	191	13	0.263	0.953
SAO prescriptions	12	14	33	2	20	0.976	0.738

Note: All charges were adjusted to 2014 U.S. dollars using the Consumer Price Index.

^aTwo comparator cohorts were identified with January 1, 2012, and January 1, 2014, as their index dates.

LAO = long-acting opioid; OER = oxycodone HCl extended-release tablets; PPPM = per patient per month; SAO = short-acting opioid.