The impact of persistence with therapy on inpatient admissions and emergency room visits in the US among patients with multiple sclerosis

Figures & data

Table 1. Patient demographics, insurance plans, and cost-sharing index stratified by persistent vs non-persistent and adherent vs non-adherent status.

	Total	Persistent	Non-persistent	Adherent	Non-adherent
	(n = 16,218)	(n = 10,494)	(n = 5724)	(n = 13,971)	(n = 2247)
Age, mean (SD), years	44.5 (10.8)	44.7 (10.8)	44.0 (10.9)^a	44.6 (10.8)	43.6 (10.8)^a
18–34 years, %	19.4	18.5	21.2^a	19.2	21.1^a
35–44 years, %	30.2	30.2	30.1	29.7	33.0
45–54 years, %	30.9	31.3	30.2	31.2	29.2
55–64 years, %	17.3	17.8	16.4	17.7	14.6
≥65 years, %	2.2	2.3	2.1	2.2	2.1
Male, %	22.9	24.4	20.2^a	23.6	18.9^a
Urban residence, %	86.2	86.2	86.2	86.1	87.0
Geographic region, %
Northeast	21.5	21.9	20.7^a	21.9	18.7^a
North central	25.1	26.0	23.6	25.6	22.2
South	33.7	32.9	35.3	33.3	36.7
West	18.4	18.1	18.8	18.0	20.9
Unknown	1.3	1.2	1.5	1.3	1.6
Commercial primary payer, %	96.4	96.4	96.2	96.4	96.4
Health plan type, %
PPO or comprehensive	61.0	61.0	61.0^b	61.3	59.5^a
HMO or EPO	16.2	15.7	17.1	15.3	21.5
POS, CDHP, or HDHP	15.0	15.3	14.4	15.4	12.2
Unknown	7.8	8.1	7.4	8.0	6.9
Capitated healthcare plan, %	6.3	6.0	6.8^b	5.9	8.5^a
Index year, %
2009	36.8	35.4	39.5^a	36.6	38.2
2010	34.4	34.5	34.0	34.3	34.6
2011	28.8	30.1	26.5	29.1	27.2
Cost-sharing index for 30-day supply of MS study drug, mean (SD), $	66 (89)	66 (90)	67 (86)	66 (90)	66 (82)
Cost share is ≤$25, %	23.9	24.9	22.2^a	24.4	21.0^a
Cost share is $26–$50, %	30.1	30.0	30.3	29.8	32.0
Cost share is $51–$100, %	21.6	21.8	21.3	21.8	20.3
Cost share is ≥$101, %	15.6	15.9	15.0	15.6	15.8
Cost share is missing, %	8.7	7.4	11.2	8.4	10.9

^ap < 0.001.

^bp ≤ 0.05.

CDHP, Consumer-driven health plan; EPO, Exclusive provider organization; HDHP, High-deductible health plan; HMO, Health maintenance organization; MS, Multiple sclerosis; POS, Point-of-service; PPO, Preferred provider organization.

Table 2. Patient conditions and utilization during the 6-month pre-index period stratified by persistent vs non-persistent and adherent vs non-adherent status.

	Total	Persistent	Non-persistent	Adherent	Non-adherent
	(n = 16,218)	(n = 10,494)	(n = 5724)	(n = 13,971)	(n = 2247)
Deyo Charlson Comorbidity Index, mean (SD)	0.3 (0.8)	0.3 (0.8)	0.3 (0.8)	0.3 (0.8)	0.3 (0.8)
Optic neuritis, %	8.8	9.4	7.6^a	9.2	6.4^a
Bladder dysfunction, %	3.4	3.5	3.3	3.6	2.8
Neuropathic pain, %	10.2	10.9	8.7^a	10.4	8.5^b
Other chronic pain, %	31.0	31.7	29.8^b	31.8	26.3^a
Depression, %	11.9	10.9	13.6^a	11.7	13.0
Anxiety, %	5.2	5.1	5.4	5.2	5.2
Treatment-naive, %	79.9	77.4	84.4^a	78.6	87.6^a
Corticosteroid use, %^c	37.9	38.7	36.4^b	38.6	33.3^a
Inpatient admission, %	12.9	13.0	12.9	13.1	12.1
MS-related inpatient admission, %	5.2	5.3	5.1	5.4	4.1^b
ER visit, %	22.0	21.8	22.5	22.4	19.6^b
MS-related ER visit, %	2.4	2.4	2.5	2.5	2.3
Total healthcare costs, mean (SD), $	12,610 (15,643)	13,045 (14,752)	11,811 (17,130)^a	13,000 (15,595)	10,183 (15,724)^a
Total MS-related healthcare costs, mean (SD), $	6237 (9256)	6783 (9314)	5237 (9067)^a	6550 (9362)	4294 (8317)^a

^ap < 0.001.

^bp < 0.05.

^cOral, self-injectable, or intravenous.

ER, Emergency room; MS, Multiple sclerosis.

Figure 1. Unadjusted proportions of patients with an inpatient admission or ER visit during the 1-year follow-up period. (A) Persistent and non-persistent patients. (B) Adherent and non-adherent patients.

Table 3. Persistence and adherence during 1-year follow-up period stratified by presence of inpatient admission or ER visit during 1-year follow-up period.

	Total	Patients with inpatient admission during follow-up	Patients with no inpatient admission during follow-up	Patients with ER visit during follow-up	Patients with no ER visit during follow-up
	(n = 16,218)	(n = 1620)	(n = 14,598)	(n = 4036)	(n = 12,182)
Time persistent on index drug during follow-up, days
Mean (SD)	290.1 (111.6)	260.2 (120.8)	293.4 (110.0)^a	273.9 (117.5)	295.5 (109.1)^a
Minimum	1	1	1	1	1
25th Percentile	201	144	210	171	218
Median	365	365	365	365	365
75th Percentile	365	365	365	365	365
Maximum	365	365	365	365	365
Discontinuation rate during follow-up^c
Patients who discontinued, %	35.3	48.4	33.8^a	42.3	33.0^a
Sum of PYs	12,891	1155	11,736	3028	9863
Rate per 100 PY (95% CI)	44.4 (43.2–45.6)	67.9 (63.1–72.6)	42.1 (40.9–43.3)	56.3 (53.7–59.0)	40.7 (39.5–42.0)
MPR during persistent period
Mean (SD)	0.92 (0.13)	0.92 (0.13)	0.92 (0.14)^b	0.92 (0.13)	0.92 (0.14)
Minimum	0.00	0.00	0.00	0.00	0.00
25th Percentile	0.90	0.87	0.90	0.89	0.90
Median	0.99	0.99	1.00	0.99	1.00
75th Percentile	1.00	1.00	1.00	1.00	1.00
Maximum	1.00	1.00	1.00	1.00	1.00
Adherent Patients, %^d	86.1	85.4	86.2	85.5	86.4

^ap < 0.05.

^bp < 0.001.

^cDiscontinuation is defined as a gap of >60 days without index drug. Time to discontinuation is defined as last day with drug on hand prior to gap >60 days.

^dAdherent patients were those with an MPR ≥0.80.

ER, Emergency room; MPR, Medication possession ratio; PY, Person-year.

Table 4. Adjusted odds ratios of having an inpatient admission or ER visit during the 1-year follow-up period.

	Inpatient admission		ER visit
	AOR (95% CI)	AOR (95% CI)	AOR (95% CI)	AOR (95% CI)
Adherent vs Not adherent	0.83 (0.71–0.97)		0.86 (0.77–0.95)
Persistent vs Not persistent		0.50 (0.45–0.56)		0.64 (0.60–0.69)
Covariates
Male gender	0.97 (0.86–1.11)	1.00 (0.88–1.14)	0.84 (0.77–0.92)	0.85 (0.78–0.93)
Age 65+ vs 18–34	3.65 (2.72–4.89)	3.81 (2.84–5.12)	1.26 (0.99–1.62)	1.29 (1.00–1.65)
Age 55–64 vs 18–34	2.21 (1.86–2.64)	2.29 (1.91–2.73)	1.06 (0.94–1.19)	1.07 (0.95–1.21)
Age 45–54 vs 18–34	1.56 (1.32–1.84)	1.60 (1.36–1.89)	0.86 (0.77–0.96)	0.87 (0.78–0.97)
Age 35–44 vs 18–34	1.12 (0.94–1.33)	1.15 (0.97–1.36)	0.91 (0.81–1.01)	0.92 (0.82–1.02)
Urban vs rural location	0.99 (0.85–1.16)	0.99 (0.85–1.16)	0.94 (0.84–1.05)	0.94 (0.84–1.05)
West vs Northeast	0.89 (0.74–1.07)	0.88 (0.73–1.06)	0.84 (0.74–0.95)	0.84 (0.74–0.95)
South vs Northeast	1.02 (0.88–1.19)	1.01 (0.87–1.18)	0.95 (0.86–1.06)	0.95 (0.85–1.05)
North Central vs Northeast	1.10 (0.94–1.29)	1.11 (0.94–1.30)	1.03 (0.93–1.16)	1.04 (0.93–1.16)
HMO/EPO vs Comprehensive/PPO	0.89 (0.76–1.04)	0.89 (0.76–1.05)	0.99 (0.90–1.11)	1.00 (0.90–1.11)
POS/CHDP/HDHP vs PPO/Comprehensive	0.92 (0.78–1.07)	0.92 (0.79–1.08)	1.01 (0.91–1.12)	1.01 (0.91–1.13)
Unknown health plan vs PPO/Comprehensive	1.09 (0.89–1.34)	1.11 (0.90–1.36)	1.11 (0.96–1.28)	1.12 (0.97–1.30)
CCI	1.16 (1.10–1.22)	1.16 (1.10–1.22)	1.13 (1.08–1.18)	1.13 (1.08–1.18)
Pre-period corticosteroid use	1.16 (1.04–1.30)	1.17 (1.05–1.31)	1.11 (1.02–1.19)	1.11 (1.03–1.20)
Treatment-naïve	1.21 (1.04–1.40)	1.16 (1.01–1.35)	1.05 (0.95–1.16)	1.03 (0.93–1.14)
Pre-period hospitalization	2.01 (1.73–2.32)	2.00 (1.73–2.31)	1.05 (0.94–1.18)	1.04 (0.93–1.17)
Pre-period ER visit	1.49 (1.32–1.68)	1.47 (1.30–1.66)	2.40 (2.20–2.61)	2.39 (2.19–2.60)
Pre-period total expenditures (log)	1.19 (1.12–1.26)	1.21 (1.14–1.27)	1.10 (1.06–1.14)	1.11 (1.07–1.15)

AOR, Adjusted odds ratio; CDHP, Consumer-driven health plan; EPO, Exclusive provider organization; ER, Emergency room; HDHP, High-deductible health plan; HMO, Health maintenance organization; POS, Point-of-service; PPO, Preferred provider organization.