Table 3.

Associations of MS disease course and disability with risk of serious infection stratified by disease modifying therapy, overall and by attained age.

	Overall			Attained age
				<40 yrs		40–60 yrs		>60 yrs
	Total N	N events	HR (95% CI)	N events	HR (95% CI)	N events	HR (95% CI)	N events	HR (95% CI)
Never DMT
MS clinical course
Relapsing-remitting	2601	229	1.49 (1.31; 1.70)	62	1.39 (1.07; 1.79)	126	1.52 (1.27; 1.82)	41	1.64 (1.20; 2.24)
Progressive	1667	454	3.76 (3.41; 4.14)	39	5.94 (4.29; 8.23)	232	3.98 (3.47; 4.57)	183	2.82 (2.42; 3.29)
MS EDSS score
0.0–5.5 (mild/moderate)	2706	197	1.10 (0.96; 1.27)	29	0.69 (0.48; 1.00)	108	1.16 (0.95; 1.40)	60	1.38 (1.07; 1.79)
6.0–9.5 (severe)	954	279	4.35 (3.85; 4.91)	28	7.52 (5.14; 11.00)	130	4.75 (3.98; 5.68)	121	3.72 (3.09; 4.47)
Ever DMT
MS clinical course
Relapsing-remitting	2592	250	2.22 (1.95; 2.53)	162	2.49 (2.11; 2.93)	83	1.91 (1.53; 2.38)	5	1.82 (0.75; 4.39)
Progressive	522	84	4.37 (3.52; 5.42)	20	3.81 (2.45; 5.94)	55	4.61 (3.52; 6.03)	9	3.49 (1.81; 6.74)
MS EDSS score
0.0–5.5 (mild/moderate)	2396	182	1.63 (1.41; 1.90)	103	1.64 (1.34; 2.01)	73	1.62 (1.28; 2.05)	6	1.93 (0.86; 4.30)
6.0–9.5 (severe)	434	64	5.18 (4.05; 6.63)	15	3.86 (2.31; 6.43)	43	6.32 (4.67; 8.55)	6	3.54 (1.59; 7.92)

Hazard ratios comparing rates of serious infections in MS patient groups by disease course and disability and stratified by disease modifying therapy with rates in matched individuals from the general population without MS (= reference). All hazard ratios are derived from flexible parametric models and are adjusted for the matching factors (age sex and region of residence) and for educational attainment and calendar period of cohort entry.

Abbreviations: MS = multiple sclerosis; EDSS = Expanded Disability Status Scale; HR = hazard ratio; CI = confidence interval; REF = reference category, DMT, disease modifying therapy. DMT is defined as Rituximab, Natalizumab, Alemtuzumab, Dimethyl Fumarate or Fingolimod.