Results of sustained long-term use of interferon beta-1a in a community-based cohort of patients with relapsing multiple sclerosis

Figures & data

Table 1. Baseline characteristics and patient outcomes.

Variable	Mean (SD) or %	n
Age, mean years (SD)	51.0 (12.1)	364
Female, %	79.9	291
MS pattern, %
Relapsing Remitting MS (RRMS)	76.9	280
Clinically Isolated Syndrome (CIS)	23.1	84
Age at MS onset, mean years (SD)	41.6 (11.57)	364
Duration of disease, mean years (SD)	9.39 (7.02)	363
Number of relapses in 12 months prior, mean (SD)	1.06 (0.67)	364
Used other DMT prior to IFNβ1a, %	19.2	70
Time from diagnosis to start of IFNβ1a, %
<1 year	67.3	245
≥1 year	31.3	114
EDSS, mean (SD)
Baseline	2.37 (1.13)	364
End of observation	2.38 (1.39)	364
Change	0.018 (1.25)	364
Time to first on IFNβ1a relapse, mean years (SD)
Overall	5.58 (0.26)	364
RRMS	5.36 (0.30)	280
CIS	6.16 (0.51)	84
Annualized relapse rate, mean (SD)
Overall	0.30 (0.55)	364
RRMS	0.31 (0.56)	280
CIS	0.25 (0.48)	84
Relapsed while on IFNβ1a, %	44.0	160
Time on IFNβ1a, mean years (SD)	4.03 (2.56)	364
Discontinued IFNβ1a during observation, %	35.7	130
Reason for discontinuing IFNβ1a, %
Side-effects	30.8	40
Breakthrough disease evidenced by relapse	23.1	30
Breakthrough disease evidenced by MRI changes	12.3	16
Pregnancy	10.8	14
Cost of IFNβ1a	8.5	11
Transition to progressive MS	3.1	4
Other	11.5	15

Table 2. Cox proportional hazard model: Risk of on-IFNβ1a relapse (n = 361).

Variable	Hazard ratio	95% CI	p Value
EDSS at baseline	1.17	1.01–1.35	0.03
Age at MS onset (years)	0.97	0.96–0.98	<0.001
# of relapses in 12 months prior to start of IFNβ1a	1.44	1.14–1.81	<0.01
Time from diagnosis to start of IFNβ1a
<1 year (ref)
≥1 year	0.62	0.41–0.92	0.02

Table 3. Factors associated with having an on-IFNβ1a relapse (n = 364).

Variable	Adjusted Odds Ratio	95% CI	p Value
Age at MS onset (years)	0.96	0.94–0.98	<0.001
# of relapses in 12 months prior to start of IFNβ1a	1.62	1.14–2.29	<0.01
Time on IFNβ1a	1.10	1.00–1.22	0.05
Time from diagnosis to start of IFNβ1a
<1 year (ref)
≥1 year	0.50	0.24–1.03	0.06
EDSS at baseline	1.20	0.97–1.48	0.10
Prior DMT
No (ref)
Yes	1.00	0.53–1.92	0.99
Duration of MS (years)	1.00	0.96–1.05	0.82

Table 4. Reported adverse events.

Adverse event	n	% of total sample
Flu-like symptoms	260	71.4%
Cutaneous injection reactions	23	6.3%
Infection
Respiratory	152	41.8%
Urinary tract	51	14.0%
Flu	19	5.2%
Bacterial dermatitis	8	2.2%
Eye infection	4	1.1%
Herpes Zoster	4	1.1%
Herpes Simplex	1	0.3%
Other	17	4.7%
Depression
Diagnosed after baseline	14	3.8%
Worsened on IM IFNβ1a	27	7.4%
Suicidal thinking	8	2.2%
Suicide attempts	2	0.5%
Suicide death	1	0.3%
Hepatic dysfunction
LFT > 3 × ULN	4	1.1%
Cardiovascular
Hypertension	1	0.3%
Tachycardia	3	0.8%
Heart failure^a	1	0.3%
Cancer
Breast^b	3	0.8%
Colon	1	0.3%
Prostate	1	0.3%
Lung^c	1	0.3%
Basal Cell	1	0.3%

^aOne death.

^bTwo deaths.

^cOne death.

Table 5. Factors associated with discontinuation of IFNβ1a (n = 364).

Variable	Adjusted Odds Ratio	95% CI	p Value
ARR
ARR = 0 (ref)
ARR < 0.4	1.60	0.56–2.02	0.85
ARR ≥ 0.4	7.65	4.21–13.88	<0.001
Age at MS onset (years)	1.01	0.98–1.03	0.62
EDSS at baseline	1.00	0.82–1.30	0.78
# of relapses in 12 months prior to start of IFNβ1a	0.96	0.66–1.40	0.84
Time from diagnosis to start of IFNβ1a
<1 year (ref)
≥1 year	1.00	0.47–2.14	0.99
Prior DMT
No (ref)
Yes	1.47	0.74–2.93	0.27
Duration of MS (years)	1.00	0.95–1.04	0.84