. Author manuscript; available in PMC: 2023 Oct 9.

Published in final edited form as: Mult Scler. 2018 Jun 22;25(8):1162–1169. doi: 10.1177/1352458518783343

Table 3.

Risk of MS and ambient UVR exposure by age-specific period and season.

Age	Ambient Winter UVR	No. cases	HR	95%CI			Ambient Summer UVR	No. cases	HR	95%CI			Ambient Annual UVR	No. cases	HR	95%CI
Lifetime Average	<22	44	2.00	1.21	-	3.30	<185	45	1.25	0.77	-	2.03	<103	39	1.50	0.91	-	2.49
	22-31	46	1.80	1.10	-	2.95	185-195	33	0.96	0.57	-	1.61	103-112	40	1.22	0.74	-	2.01
	31-49	34	1.34	0.79	-	2.26	195-232	44	0.85	0.52	-	1.38	112-141	44	1.09	0.67	-	1.78
	>49	24	Ref.				>232	26	Ref.				>141	25	Ref.
	p-trend		0.004				p-trend		0.15				p-trend		0.03

≤12	<22	56	1.59	0.95	-	2.67	<185	56	1.18	0.73	-	1.90	<103	52	1.26	0.78	-	2.06
	22-31	41	1.17	0.68	-	2.00	185-195	40	0.88	0.53	-	1.46	103-112	46	0.93	0.57	-	1.53
	31-49	31	1.10	0.63	-	1.93	195-232	28	0.71	0.41	-	1.23	112-141	26	0.69	0.39	-	1.20
	>49	20	Ref.				>232	24	Ref.				>141	24	Ref.
	p-trend		0.02				p-trend		0.30				p-trend		0.09

13-19	<22	55	1.55	0.94	-	2.57	<185	52	1.19	0.73	-	1.96	<103	50	1.46	0.88	-	2.44
	22-31	40	1.13	0.67	-	1.93	185-195	41	0.98	0.59	-	1.64	103-112	44	1.07	0.64	-	1.81
	31-49	32	1.12	0.64	-	1.94	195-232	32	0.88	0.51	-	1.50	112-141	33	1.04	0.6	-	1.80
	>49	21	Ref.				>232	23	Ref.				>141	21	Ref.
	p-trend		0.03				p-trend		0.45				p-trend		0.16

20-39	<22	44	1.57	0.97	-	2.53	<185	43	1.05	0.67	-	1.65	<103	43	1.32	0.84	-	2.08
	22-31	40	1.35	0.83	-	2.21	185-195	37	1.03	0.65	-	1.63	103-112	38	1.02	0.64	-	1.62
	31-49	34	1.24	0.75	-	2.05	195-232	30	0.79	0.49	-	1.29	112-141	31	0.89	0.54	-	1.45
	>49	27	Ref.				>232	35	Ref.				>141	33	Ref.
	p-trend		0.05				p-trend		0.65				p-trend		0.24

40-64	<22	35	1.31	0.79	-	2.15	<185	32	1.15	0.68	-	1.94	<103	31	1.38	0.81	-	2.35
	22-31	23	0.87	0.50	-	1.51	185-195	19	0.85	0.47	-	1.55	103-112	25	1.03	0.59	-	1.81
	31-49	17	0.68	0.37	-	1.24	195-232	27	1.01	0.58	-	1.74	112-141	23	0.94	0.53	-	1.67
	>49	28	Ref.				>232	25	Ref.				>141	24	Ref.
	p-trend		0.61				p-trend		0.87				p-trend		0.74

MS: multiple sclerosis; UVR: ultraviolet radiation; HR: hazard ratio; CI: confidence interval; USRT: US Radiologic Technologists.

All analyses adjusted for birth cohort (<1945, 1945-1950, 1950-1955 and >1955), race (White, non-White) and sex (male, female). Cox proportional hazards analysis using attained age as time scale. Exposure categories based on the distribution of doses for the USRT study population during the age period 20–39 years, the time closest, and prior, to the age at diagnosis for multiple sclerosis. Participants missing UVR data for one or more addresses are excluded. Categorical values modeled as continuous for trend tests. Results not shown for ages 65+ because only 1 MS cases diagnosed during that period. UVR in units of J/m².