TABLE 1.

Demographics Pre-DMT Initiation

	Overall		Persistent in Initiation Year		Nonpersistent in Initiation Year		P Valuea
	N	%	N	%	N	%
Total	2,407	—	1,800	74.78	607	25.22
Gender							0.259
Male	621	25.80	450	25.00	171	28.17
Female	1,785	74.16	1,349	74.94	436	71.83
Age group							0.923
0-35	404	16.78	297	16.50	107	17.63
36-44	745	30.95	558	31.00	187	30.81
45-54	843	35.02	635	35.28	208	34.27
55+	415	17.24	310	17.22	105	17.30
Payer type							0.239
Commercial	1,504	62.48	1,135	63.06	369	60.79
Medicaid or Medicare	42	1.74	29	1.61	13	2.14
Self-insured	861	35.77	636	35.33	225	37.07
Insurance type							0.498
Health maintenance organization	288	11.97	213	11.83	75	12.36
Indemnity	100	4.15	75	4.17	25	4.12
Preferred provider network	1,831	76.07	1,382	76.78	449	73.97
Point of service	154	6.40	105	5.83	49	8.07
Consumer driven	13	0.54	9	0.50	4	0.66
Unknown	21	0.87	16	0.89	5	0.82
Region							0.216
East	743	30.87	557	30.94	186	30.64
Midwest	716	29.75	551	30.61	165	27.18
South	696	28.92	502	27.89	194	31.96
West	252	10.47	190	10.56	62	10.21
MS-related symptoms b
Visual	454	18.86	326	18.11	128	21.09	0.105
Movement disorders	662	27.50	507	28.17	155	25.54	0.209
Facial neuralgia	52	2.16	35	1.94	17	2.80	0.210
Dizziness	220	9.14	157	8.72	63	10.38	0.221
Fatigue	52	2.16	38	2.11	14	2.31	0.775
Paralysis	111	4.61	84	4.67	27	4.45	0.824
Headache	33	1.37	25	1.39	8	1.32	0.897
Muscle	245	10.18	178	9.89	67	11.04	0.418
Speech	42	1.74	31	1.72	11	1.81	0.884
Skin disturbance	432	17.95	319	17.72	113	18.62	0.620
Movement aids c
Walker	80	3.32	64	3.56	16	2.64	0.274
Wheelchair	77	3.20	21	1.17	56	9.23	0.673
Prior DMT use (yes)d	1,426	59.24	1,111	61.72	315	51.89	< 0.001
Charlson Comorbidity Index (mean, SD)	3.43	1.85	3.41	1.84	3.48	1.91	0.467
Relapse count	0.57	1.14	0.55	1.09	0.62	1.27	0.239

^a P value difference between persistent and nonpersistent natalizumab initiators within initiation year; chi-squared distributional test for categorical variables; t-test used for continuous variables.

^b Symptom codes identified in Table 1 published in Curkendall et al.³³

^c Movement aid codes identified in Appendix B (available in online article).

^d Prior DMT use was defined as any claim for interferon beta 1a IM, interferon beta 1a SC, interferon beta 1b SC, or glatiramer acetate during the 12-month period prior to index date.

DMT = disease-modifying therapy; ICD-9-CM = International Classification of Diseases, Ninth Revision, Clinical Modification; IM = intramuscular; SC = subcutaneous; SD = standard deviation.