Healthcare resource utilization following switch or discontinuation in multiple sclerosis patients on disease modifying drugs

Figures & data

Table 1. Baseline characteristics of multiple sclerosis population.

Patient characteristic	All MS patients(n = 27,513)		Interferon-β1a IM(n = 2,019)		Interferon-β1b SC(n = 576)		Glatiramer acetate(n = 2,081)		Interferon-β1a SC(n = 1,096)
	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Age, years (mean, SD)	43.23	9.73	43.39	9.82	43.22	9.73	43.38	9.51	42.67	9.94
	n	%	n	%	n	%	n	%	n	%
Age, categorized (n, %)
0–17	28	0.49	13	0.23	3	0.05	8	0.14	4	0.07
18–24	172	2.98	62	1.07	18	0.31	45	0.78	47	0.81
25–34	940	16.29	306	5.30	93	1.61	347	6.01	194	3.36
35–44	1,869	32.38	671	11.63	172	2.98	696	12.06	330	5.72
45–54	2,038	35.31	707	12.25	222	3.85	718	12.44	391	6.77
55–64	725	12.56	260	4.50	68	1.18	267	4.63	130	2.25
65+	—	—	—	—	—	—	—	—	—	—
Gender (n, %)
Male	1,262	21.86	427	7.40	154	2.67	424	7.35	257	4.45
Female	4,510	78.14	1,592	27.58	422	7.31	1,657	28.71	839	14.54
Geographic region (n, %)
East	1,028	17.81	368	6.38	91	1.58	409	7.09	160	2.77
South	1,120	19.40	377	6.53	98	1.70	393	6.81	252	4.37
Midwest	2,671	46.28	967	16.75	321	5.56	916	15.87	467	8.09
West	953	16.51	307	5.32	66	1.14	363	6.29	217	3.76
Plan type (n, %)
Consumer directed health care	6	0.10	4	0.07	—	—	1	0.02	1	0.02
Health maintenance organization	2,512	43.52	874	15.14	322	5.58	948	16.42	368	6.38
Indemnity plan	200	3.47	76	1.32	27	0.47	45	0.78	52	0.90
Point of service plan	870	15.07	260	4.50	82	1.42	351	6.08	177	3.07
Preferred provider organization	2,143	37.13	789	13.67	140	2.43	723	12.53	491	8.51
Other or unknown	41	0.71	16	0.28	5	0.09	13	0.23	7	0.12
Index year (n, %)
1996	11	0.19	5	0.09	6	0.10	—	—	—	—
1997	15	0.26	5	0.09	5	0.09	5	0.09	—	—
1998	119	2.06	63	10.90	27	0.47	29	0.50	—	—
1999	222	3.85	132	2.29	28	0.49	62	10.70	—	—
2000	483	8.37	209	3.62	79	1.37	195	3.38	—	—
2001	502	8.70	225	3.90	87	1.51	190	3.29	—	—
2002	638	11.05	175	3.03	99	1.72	237	4.11	127	2.20
2003	1,656	28.69	553	9.58	182	3.15	529	9.16	392	6.79
2004	1,679	29.09	510	8.84	52	0.90	667	11.56	450	7.80
2005	447	7.74	142	2.46	11	0.19	167	2.89	127	2.20
Drug exposures during baseline (n, %)
Any MS treatment before index	910	15.77	98	1.70	115	1.99	322	5.58	375	6.50
Interferon-β1a IM	541	9.37	—	—	65	1.13	22	3.85	254	4.40
Interferon-β1b SC	127	2.20	25	0.43	—	—	74	1.28	28	0.49
Glatiramer acetate	187	3.24	52	0.90	42	0.73	—	—	93	1.61
Interferon-β1a SC	58	1.00	18	0.31	10	0.17	30	0.52	—	—
Natalizumab	4	0.07	3	0.05	—	—	—	—	1	0.02

n, number of patients with characteristic; SD, standard deviation; MS, multiple sclerosis; MRI, magnetic resonance imaging; NEC, necrotizing enterocolitis; SC, subcutaneous; IM, intramuscular.

Table 2. Cox proportional hazards model of time to treatment change or discontinuation.

Change treatment
Predictor	Hazard ratios	95% hazard ratio CI
Index drug
Glatiramer acetate	0.619	0.51	0.751
Interferon-β1b SC	1.249	0.969	1.612
Interferon-β1a SC	0.884	0.71	1.1
Interferon-β1a IM	ref
Prior use of MS drugs
Yes	2.46	2.06	2.9520
No	ref
Gender
Female	1.41	1.15	1.72
Male	ref
Age
0–34	1.63	1.34	1.9860
35–44	1.16	0.97	1.40
45–54	ref
55–64	0.71	0.53	0.95
Index year
1998–2000	0.75	0.57	0.97
2001–2002	ref
2003–2006	0.82	0.68	0.9890
Costs
Cost of emergency services	1.11	1.04	1.1980
Cost of MRI	1.05	1.01	1.1020
Cost of outpatient services	1.01	1.00	1.0180
Discontinuation
Variable	Hazard ratios	95% hazard ratio CI
Index drug
Glatiramer acetate	1.101	0.99	1.224
Interferon-β1b SC	2.458	2.141	2.822
Interferon-β1a SC	1.05	0.918	1.202
Interferon-β1a IM	ref
Health insurance provider
HMO	0.89	0.81	0.9810
Other	ref
Prior use of MS drugs
Yes	0.77	0.67	0.8750
No	ref
Gender
Female	0.99	0.89	1.10
Male	ref
Age
0–34	1.24	1.10	1.3950
35–44	1.02	0.92	1.14
45–54	ref
55–64	0.98	0.86	1.13
Region
South	1.18	1.06	1.31
Other	ref
Index year
1998–2002	ref
2003–2006	1.46	1.31	1.6250
Costs
Cost of MRI	0.87	0.84	0.8960

HMO, health maintenance organization; ref, reference level; SC, subcutaneous; IM, intramuscular.

Table 3. Cost ($) of medical services associated with treatment change or discontinuation.

Medical service	Continue initial treatment(n = 3,199)		Change treatment(n = 656)		Discontinue treatment(n = 1,917)
	Mean	SD	Mean	SD	Mean	SD
Total cost of services in 18-month period ($)
Outpatient – any diagnosis	6,723.68	12,348.14	10,267.00	18,702.78	8,360.01	17,656.50
Outpatient – MS diagnosis	3,480.07	9,419.74	6,473.84	15,718.04	4,329.56	12,123.96
Emergency room – any diagnosis	176.61	680.53	370.79	1,334.38	281.86	1,099.63
Emergency room – MS diagnosis	66.67	416.59	141.01	784.87	101.13	523.63
Inpatient – any diagnosis	1,613.42	8,524.09	3,752.17	17,487.28	3,135.12	12,510.82
Inpatient – MS diagnosis	1,087.79	6,041.03	2,505.61	9,582.92	1,824.05	8,083.88
MRI – any diagnosis	885.47	1,563.97	1,141.66	1,792.10	774.38	1,495.72
MRI – MS diagnosis	687.89	1,366.75	842.02	1,533.68	553.81	1,267.03
Pharmacy costs	19,919.84	12,557.02	17,730.40	11,352.34	7,823.07	11,140.99
Non-pharmacy medical costs	9,399.17	16,861.29	15,531.62	28,950.58	12,551.38	24,320.70
Total medical and pharmacy costs	29,319.01	20,748.54	33,262.02	31,043.89	20,374.45	27,756.15

n, number of patients; SD, standard deviation; MS, multiple sclerosis; MRI, magnetic resonance imaging.

Table 4. Linear regression model of total non-pharmacy medical costs associated with treatment change or discontinuation.

Change treatment
Predictor	Parameter estimate	Standard error	p-value
Intercept	13,862	1,408.09	< 0.0001
Health insurance provider
HMO	–1,882.31	678.68	0.0056
Other	ref
Gender
Female	–1,102.23	748.16	0.14
Male	ref
Age
0–34	–1,821.83	880.29	0.0380
35–44	–519.50	736.02	0.48
45–54	ref
55–64	1,664.05	992.95	0.09
Index year
1998–2000	–2,689.21	1,044.40	0.01
2001–2002	ref
2003–2006	1,555.33	837.99	0.06
Region
East	1,100.75	775.34	0.16
Other regions	ref
Index drug
Interferon-β1a IM	ref
Interferon-β1b SC	2,788.12	1,287.77	0.03
Glatiramer acetate	–870.33	720.44	0.23
Interferon-β1a SC	–2,564.46	906.18	0.0047
Baseline costs
Total medical costs	0.05	0.03	0.0417
Total pharmacy cost	0.24	0.12	0.0390
Cost of outpatient services	0.61	0.06	< 0.0001
Treatment persistence
Persist with initial drug	–5,497.99	817.20	< 0.0001
Changed treatment	ref
Discontinuation
Predictor	Parameter estimate	Standard error	p-value
Intercept	11,524	914.58	< 0.0001
Health insurance provider
HMO	–2,488.82	569.87	< 0.0001
Other	ref
Prior use of MS drugs
Yes	3,560.77	951.40	0.0002
No	ref
Gender
Female	161.47	650.80	0.80
Male	ref
Age
0–34	–3,598.27	774.23	< 0.0001
35–44	–1,378.20	654.22	0.04
45–54	ref
55–64	2,273.89	860.19	0.01
Index year
1998–2000	–3,002.90	816.79	0.00
2001–2006	ref
Region
East	1,305.00	692.71	0.06
Other Regions	ref
Index drug
Interferon-β1a IM	ref
Interferon-β1b SC	1,829.42	996.61	0.07
Glatiramer acetate	–749.11	643.75	0.24
Interferon-β1a SC	–657.59	826.10	0.43
Baseline costs
Total medical cost	0.06	0.02	0.0128
Total pharmacy cost	–0.24	0.10	0.0156
Cost of outpatient services	0.69	0.06	< 0.0001
Treatment persistence
Persist with initial drug	–2,882.94	562.74	< 0.0001
Discontinued treatment	ref

HMO, health maintenance organization; ref, reference level.