Table 2.
Preonset sun exposure measures and associations with hazard of MS conversion.
| Summer UVR measures and hazard of MS conversion | Winter UVR measures and hazard of MS conversion | ||||||
|---|---|---|---|---|---|---|---|
| Failures/person-years (rate) | HR (95% CI) |
Failures/person-years (rate) | HR (95% CI) |
||||
| Univariable | Adjusteda | Univariable | Adjusteda | ||||
| Summer UVR-load 6–10 years old (kJ/m2) | Winter UVR-load 6–10 years old (kJ/m2) | ||||||
| 0–228 >228–323 >323–383 >383–488 Trend: |
35/83.36 (0.42) 31/138.17 (0.22) 26/123.21 (0.21) 18/103.78 (0.17) |
1.00 (reference) 0.60 (0.36, 0.98) 0.56 (0.34, 0.91) 0.44 (0.25, 0.78) p = 0.004 |
1.00 (reference) 0.73 (0.43, 1.25) 0.75 (0.42, 1.34) 0.47 (0.25, 0.86) p = 0.020 |
0–31 >31–52 >52–100 >100–544 Trend: |
33/88.78 (0.37) 33/124.15 (0.27) 22/125.50 (0.18) 22/110.09 (0.20) |
1.00 (reference) 0.75 (0.46, 1.22) 0.53 (0.30, 0.92) 0.57 (0.33, 0.96) p = 0.017 |
1.00 (reference) 0.87 (0.50, 1.52) 0.60 (0.32, 1.15) 0.46 (0.23, 0.92) p = 0.025 |
| Summer UVR-load 11–15 years old (kJ/m2) | Winter UVR-load 11–15 years old (kJ/m2) | ||||||
| 0–229 >229–313 >313–360 >360–482 Trend: |
35/83.15 (0.42) 30/102.36 (0.29) 29/157.05 (0.19) 16/105.96 (0.15) |
1.00 (reference) 0.71 (0.43, 1.18) 0.48 (0.29, 0.79) 0.39 (0.21, 0.72) p = 0.001 |
1.00 (reference) 0.86 (0.51, 1.44) 0.62 (0.35, 1.09) 0.48 (0.25, 0.90) p = 0.012 |
0–33 >33–53 >53–104 >104–530 Trend: |
32/105.92 (0.30) 33/100.31 (0.33) 20/134.19 (0.15) 25/108.10 (0.23) |
1.00 (reference) 1.07 (0.66, 1.74) 0.55 (0.31, 0.99) 0.78 (0.47, 1.29) p = 0.093 |
1.00 (reference) 1.20 (0.69, 2.09) 0.63 (0.33, 1.19) 0.72 (0.39, 1.32) p = 0.14 |
| Summer UVR-load 16–20 years old (kJ/m2) | Winter UVR-load 16–20 years old (kJ/m2) | ||||||
| 0–188 >188–266 >266–337 >337–491 Trend: |
36/86.43 (0.42) 29/103.58 (0.28) 28/131.22 (0.21) 17/127.29 (0.13) |
1.00 (reference) 0.67 (0.41, 1.09) 0.55 (0.33, 0.92) 0.37 (0.21, 0.66) p < 0.001 |
1.00 (reference) 0.72 (0.42, 1.23) 0.75 (0.44, 1.29) 0.52 (0.28, 0.97) p = 0.054 |
0–28 >28–45 >45–80 >80–556 Trend: |
36/88.02 (0.41) 34/119.76 (0.28) 19/111.86 (0.17) 21/128.88 (0.16) |
1.00 (reference) 0.73 (0.46, 1.15) 0.47 (0.26, 0.84) 0.46 (0.27, 0.76) p = 0.001 |
1.00 (reference) 0.81 (0.48, 1.36) 0.52 (0.27, 1.00) 0.48 (0.27, 0.84) p = 0.008 |
| Summer UVR-load 21–25 years old (kJ/m2) | Winter UVR-load 21–26 years old (kJ/m2) | ||||||
| 0–148 >148–237 >237–329 >329–494 Trend: |
28/74.94 (0.37) 29/88.83 (0.33) 22/113.64 (0.19) 20/154.98 (0.13) |
1.00 (reference) 0.81 (0.46, 1.43) 0.54 (0.30, 0.99) 0.38 (0.21, 0.69) p = 0.001 |
1.00 (reference) 0.96 (0.53, 1.74) 0.68 (0.35, 1.31) 0.50 (0.26, 0.96) p = 0.020 |
0–24 >24–44 >44–85 >85–285 Trend: |
34/83.92 (0.41) 24/109.24 (0.22) 17/104.21 (0.16) 24/135.03 (0.18) |
1.00 (reference) 0.60 (0.35, 1.04) 0.45 (0.25, 0.83) 0.50 (0.30, 0.83) p = 0.006 |
1.00 (reference) 0.56 (0.31, 1.01) 0.46 (0.24, 0.88) 0.47 (0.27, 0.82) p = 0.010 |
| Summer UVR-load 26–30 years old (kJ/m2) | Winter UVR-load 26–30 years old (kJ/m2) | ||||||
| 0–143 >143–228 >228–329 >329–510 Trend: |
27/65.73 (0.41) 26/86.43 (0.30) 20/102.05 (0.20) 17/148.47 (0.12) |
1.00 (reference) 0.73 (0.42, 1.29) 0.53 (0.30, 0.95) 0.32 (0.17, 0.61) p < 0.001 |
1.00 (reference) 0.82 (0.44, 1.55) 0.58 (0.30, 1.10) 0.40 (0.19, 0.85) p = 0.012 |
0–21 >21–44 >44–70 >70–411 Trend: |
29/80.78 (0.36) 26/104.91 (0.25) 19/93.85 (0.20) 16/123.12 (0.13) |
1.00 (reference) 0.76 (0.44, 1.29) 0.62 (0.34, 1.14) 0.42 (0.23, 0.78) p = 0.005 |
1.00 (reference) 0.80 (0.43, 1.49) 0.69 (0.34, 1.41) 0.37 (0.19, 0.75) p = 0.005 |
| Summer UVR-load 31–35 years old (kJ/m2) | Winter UVR-load 31–35 years old (kJ/m2) | ||||||
| 0–136 >136–218 >218–328 >328–465 Trend: |
26/65.70 (0.40) 17/76.95 (0.22) 18/109.99 (0.16) 16/96.35 (0.17) |
1.00 (reference) 0.59 (0.31, 1.12) 0.47 (0.25, 0.87) 0.46 (0.25, 0.85) p = 0.009 |
1.00 (reference) 0.84 (0.41, 1.74) 0.79 (0.36, 1.72) 0.78 (0.37, 1.62) p = 0.50 |
0–22 >22–37 >37–69 >69–214 Trend: |
24/78.62 (0.31) 19/105.33 (0.18) 19/81.31 (0.23) 15/83.74 (0.18) |
1.00 (reference) 0.66 (0.35, 1.23) 0.82 (0.45, 1.49) 0.67 (0.37, 1.22) p = 0.30 |
1.00 (reference) 0.77 (0.39, 1.53) 0.92 (0.46, 1.82) 0.52 (0.26, 1.05) p = 0.12 |
| Summer UVR-load in 3 years before study entryb (kJ/m2) | Winter UVR-load in 3 years before study entry (kJ/m2) | ||||||
| 0–80 >80–90 >90–152 >152–290 Trend: |
28/103.52 (0.27) 32/62.88 (0.51) 29/92.00 (0.32) 20/178.92 (0.11) |
1.00 (reference) 1.60 (0.92, 2.76) 1.09 (0.65, 1.80) 0.44 (0.25, 0.78) p = 0.001 |
1.00 (reference) 1.74 (0.92, 3.29) 1.23 (0.71, 2.13) 0.56 (0.29, 1.05) p = 0.019 |
0–17 >17–27 >27–41 >41–125 Trend: |
32/120.02 (0.27) 33/64.41 (0.51) 22/112.22 (0.20) 22/140.66 (0.16) |
1.00 (reference) 1.63 (0.99, 2.67) 0.80 (0.46, 1.40) 0.63 (0.37, 1.05) p = 0.019 |
1.00 (reference) 1.51 (0.83, 2.75) 0.52 (0.22, 1.19) 0.28 (0.11, 0.71) p = 0.002 |
| UVR-load in summer in year of FDE (kJ/m2) | UVR-load in winter in year of FDE (kJ/m2) | ||||||
| 7–28 >28–47 >47–69 >69–96 Trend: |
33/46.32 (0.71) 28/92.25 (0.30) 26/151.17 (0.17) 19/133.64 (0.14) |
1.00 (reference) 0.52 (0.29, 0.91) 0.32 (0.19, 0.55) 0.26 (0.15, 0.47) p < 0.001 |
1.00 (reference) 0.56 (0.31, 1.01) 0.52 (0.24, 0.75) 0.34 (0.18, 0.64) p < 0.001 |
1–5 >5–9 >9–14 >14–53 Trend: |
38/71.14 (0.53) 23/128.92 (0.18) 23/112.29 (0.21) 22/111.03 (0.20) |
1.00 (reference) 0.43 (0.26, 0.73) 0.47 (0.27, 0.81) 0.46 (0.28, 0.74) p = 0.004 |
1.00 (reference) 0.47 (0.28, 0.82) 0.46 (0.25, 0.84) 0.36 (0.19, 0.66) p = 0.001 |
| UVR-load in summer 2 years before FDE (kJ/m2) | UVR-load in winter 2 years before FDE (kJ/m2) | ||||||
| 7–28 >28–50 >50–69 >69–96 Trend: |
32/46.07 (0.70) 29/106.24 (0.27) 27/143.46 (0.19) 20/135.22 (0.15) |
1.00 (reference) 0.49 (0.28, 0.84) 0.36 (0.21, 0.61) 0.29 (0.16, 0.52) p < 0.001 |
1.00 (reference) 0.49 (0.28, 0.85) 0.49 (0.28, 0.83) 0.36 (0.19, 0.68) p = 0.003 |
1–5 >5–9 >9–14 >14–53 Trend: |
40/76.92 (0.52) 23/123.15 (0.19) 25/120.84 (0.21) 20/110.08 (0.18) |
1.00 (reference) 0.45 (0.27, 0.76) 0.48 (0.29, 0.79) 0.44 (0.26, 0.74) p = 0.002 |
1.00 (reference) 0.43 (0.25, 0.75) 0.52 (0.29, 0.96) 0.33 (0.17, 0.62) p = 0.001 |
Results in bold denote statistical significance (p < 0.05). Results in italics are for tests of trend.
aAdjusted models for MS include adjustment for age, sex, and study site.
bTwo persons did not have data on their summer UVR-load in the 3 years preceding study entry.