Table 7.
Change in postonset sun exposure measures and 25(OH)D and associations with MS conversion and relapse hazard.
| MS conversion failures/person-years (rate) | MS conversion HR (95% CI) |
Relapse failures/person-years (rate) | Relapse HR (95% CI) |
|||
|---|---|---|---|---|---|---|
| Univariable | Adjusteda | Univariable | Adjustedb | |||
| Total study change in time in sun during week—summer (h/day) | ||||||
| −4, −2 h/day −1, 0, +1 h/day +2, + 4 h/day Trend: |
7/30.45 (0.23) 49/319.31 (0.15) 1/33.57 (0.03) |
1.47 (0.77, 2.82) 1.00 (reference) 0.21 (0.03, 1.31) p = 0.011 |
1.62 (0.76, 3.45) 1.00 (reference) 0.24 (0.04, 1.33) p = 0.020 |
20/65.96 (0.30) 172/667.91 (0.26) 11/90.01 (0.12) |
1.01 (0.66, 1.55) 1.00 (reference) 0.52 (0.24, 1.12) p = 0.088 |
1.13 (0.70, 1.83) 1.00 (reference) 0.46 (0.23, 0.92) p = 0.029 |
| Total study change in summer weekday UVR-load (kJ/m2) | ||||||
| −2 UVR load increments −1, 0, +1 UVR load increments +2, +3 UVR load increments Trend: |
2/1.32 (1.51) 36/212.5 (0.17) 17/132.16 (0.13) |
7.47 (4.01, 13.89) 1.00 (reference) 0.76 (0.42, 1.37) p = 0.15 |
7.24 (2.93, 17.89) 1.00 (reference) 0.63 (0.33, 1.20) p = 0.054 |
8/10.30 (0.78) 121/463.36 (0.26) 70/293.40 (0.24) |
2.16 (1.11, 4.20) 1.00 (reference) 0.96 (0.64, 1.44) p = 0.43 |
1.49 (0.76, 2.90) 1.00 (reference) 0.86 (0.60, 1.24) p = 0.20 |
| Total study change in time in sun during weekend—summer (h/day) | ||||||
| −4, −2 h/day −1, 0, +1 h/day +2, +4 h/day Trend: |
6/25.61 (0.23) 48/285.97 (0.17) 3/71.75 (0.04) |
1.40 (0.56, 3.49) 1.00 (reference) 0.25 (0.08, 0.78) p = 0.008 |
2.07 (0.78, 5.54) 1.00 (reference) 0.21 (0.06, 0.71) p = 0.001 |
39/68.15 (0.57) 145/620.53 (0.23) 19/135.19 (0.14) |
2.02 (1.06, 3.84) 1.00 (reference) 0.64 (0.35, 1.18) p = 0.011 |
2.23 (1.22, 4.09) 1.00 (reference) 0.59 (0.34, 1.04) p = 0.002 |
| Total study change in summer weekend UVR-load (kJ/m2) | ||||||
| −2 UVR load increments −1, 0, +1 UVR load increments +2, +3 UVR load increments Trend: |
0 31/136.58 (0.23) 24/209.46 (0.12) |
– 1.00 (reference) 0.50 (0.29, 0.85) p = 0.010 |
– 1.00 (reference) 0.58 (0.33, 1.02) p = 0.060 |
2/5.50 (0.36) 113/383.79 (0.29) 84/377.77 (0.22) |
0.91 (0.53, 1.56) 1.00 (reference) 0.78 (0.49, 1.23) p = 0.30 |
2.71 (1.42, 5.16) 1.00 (reference) 0.92 (0.62, 1.36) p = 0.55 |
| Total study change in time in sun during holidays—summer (h/day) | ||||||
| −4, −2 h/day −1, 0, +1 h/day +2, +4 h/day Trend: |
10/36.72 (0.27) 44/279.28 (0.16) 3/67.33 (0.05) |
1.73 (0.91, 3.30) 1.00 (reference) 0.28 (0.08, 0.98) p = 0.002 |
2.24 (1.14, 4.41) 1.00 (reference) 0.24 (0.06, 0.92) p < 0.001 |
51/110.63 (0.46) 130/564.51 (0.23) 22/148.73 (0.15) |
1.71 (1.00, 2.94) 1.00 (reference) 0.70 (0.36, 1.39) p = 0.020 |
1.75 (1.07, 2.86) 1.00 (reference) 0.65 (0.36, 1.18) p = 0.004 |
| Total study change in summer holiday UVR-load (kJ/m2) | ||||||
| −2 UVR load increments −1, 0, +1 UVR load increments +2, +3 UVR load increments Trend: |
0 35/136.43 (0.26) 19/197.12 (0.10) |
– 1.00 (reference) 0.38 (0.22, 0.66) p = 0.001 |
– 1.00 (reference) 0.37 (0.20, 0.67) p = 0.001 |
0 129/380.56 (0.34) 67/345.64 (0.19) |
– 1.00 (reference) 0.62 (0.41, 0.96) p = 0.033 |
– 1.00 (reference) 0.65 (0.45, 0.94) p = 0.021 |
| Total study change in time in sun during week—winter (h/day) | ||||||
| −4, −2 h/day −1, 0, +1 h/day +2, +4 h/day Trend: |
6/41.44 (0.15) 47/317.56 (0.15) 4/24.33 (0.16) |
0.97 (0.44, 2.13) 1.00 (reference) 1.14 (0.43, 3.03) p = 0.81 |
1.38 (0.60, 3.18) 1.00 (reference) 0.90 (0.31, 2.65) p = 0.51 |
15/72.70 (0.21) 176/705.91 (0.25) 12/45.25 (0.27) |
0.81 (0.49, 1.36) 1.00 (reference) 1.13 (0.45, 2.81) p = 0.48 |
1.11 (0.70, 1.77) 1.00 (reference) 1.07 (0.42, 2.69) p = 0.93 |
| Total study change in winter weekday UVR-load (kJ/m2) | ||||||
| −2 UVR load increments −1, 0, +1 UVR load increments +2, +3 UVR load increments Trend: |
0 36/215.45 (0.17) 19/130.58 (0.15) |
– 1.00 (reference) 0.88 (0.51, 1.52) p = 0.66 |
– 1.00 (reference) 0.62 (0.32, 1.17) p = 0.14 |
2/5.50 (0.36) 119/493.59 (0.24) 78/267.97 (0.29) |
1.05 (0.56, 1.97) 1.00 (reference) 1.11 (0.65, 1.89) p = 0.71 |
2.82 (1.49, 5.36) 1.00 (reference) 0.95 (0.57, 1.57) p = 0.76 |
| Total study change in time in sun during weekend—winter (h/day) | ||||||
| −4, −2 h/day −1, 0, +1 h/day +2, +4 h/day Trend: |
3/17.99 (0.17) 52/337.52 (0.15) 2/27.81 (0.07) |
1.11 (0.32, 3.80) 1.00 (reference) 0.48 (0.11, 2.09) p = 0.36 |
1.39 (0.41, 4.70) 1.00 (reference) 0.32 (0.06, 1.62) p = 0.099 |
11/49.77 (0.22) 187/724.03 (0.26) 5/50.08 (0.10) |
0.82 (0.46, 1.48) 1.00 (reference) 0.44 (0.15, 1.24) p = 0.33 |
1.00 (0.59, 1.71) 1.00 (reference) 0.46 (0.18, 1.22) p = 0.16 |
| Total study change in winter weekend UVR-load (kJ/m2) | ||||||
| −2 UVR load increments −1, 0, +1 UVR load increments +2, +3 UVR load increments Trend: |
0 34/209.04 (0.16) 21/136.99 (0.15) |
– 1.00 (reference) 0.93 (0.55, 1.56) p = 0.78 |
– 1.00 (reference) 0.96 (0.54, 1.72) p = 0.90 |
0 122/484.95 (0.25) 77/282.11 (0.27) |
– 1.00 (reference) 0.99 (0.52, 1.86) p = 0.96 |
– 1.00 (reference) 1.04 (0.60, 1.79) p = 0.90 |
| Total study change in time in sun during holidays—winter (h/day) | ||||||
| −4, −2 h/day −1, 0, +1 h/day +2, +4 h/day Trend: |
6/35.05 (0.17) 46/304.72 (0.15) 5/43.57 (0.12) |
1.13 (0.49, 2.60) 1.00 (reference) 0.76 (0.28, 2.10) p = 0.53 |
1.14 (0.47, 2.75) 1.00 (reference) 0.56 (0.17, 1.80) p = 0.29 |
15/77.18 (0.19) 176/743.91 (0.27) 12/102.78 (0.12) |
0.70 (0.42, 1.17) 1.00 (reference) 0.45 (0.23, 0.89) p = 0.19 |
0.87 (0.56, 1.35) 1.00 (reference) 0.50 (0.27, 0.95) p = 0.087 |
| Total study change in winter holiday UVR-load (kJ/m2) | ||||||
| −2 UVR load increments −1, 0, +1 UVR load increments +2, +3 UVR load increments Trend: |
1/1.04 (0.96) 34/197.39 (0.17) 17/122.65 (0.14) |
4.31 (2.54, 7.32) 1.00 (reference) 0.80 (0.45, 1.41) p = 0.29 |
2.18 (1.03, 4.59) 1.00 (reference) 0.60 (0.28, 1.27) p = 0.10 |
4/16.63 (0.24) 125/443.37 (0.28) 66/260.25 (0.25) |
0.69 (0.34, 1.41) 1.00 (reference) 0.87 (0.55, 1.38) p = 0.68 |
0.90 (0.42, 1.94) 1.00 (reference) 0.84 (0.55, 1.28) p = 0.43 |
| Change in as-measured 25(OH)D during study—50 nmol/L cutoff | ||||||
| Low all High, then low High all Low, then high Trend: |
7/35.37 (0.20) 7/46.92 (0.15) 32/255.83 (0.13) 14/89.85 (0.16) |
1.00 (reference) 0.79 (0.31, 2.02) 0.67 (0.30, 1.49) 0.83 (0.36, 1.96) p = 0.68 |
1.00 (reference) 0.44 (0.15, 1.26) 0.52 (0.25, 1.12) 0.59 (0.24, 1.45) p = 0.57 |
13/84.71 (0.15) 9/71.70 (0.13) 131/511.92 (0.26) 43/205.43 (0.21) |
1.00 (reference) 0.71 (0.30, 1.69) 1.43 (0.75, 2.75) 1.31 (0.64, 2.65) p = 0.23 |
1.00 (reference) 0.76 (0.34, 1.70) 1.36 (0.76, 2.42) 1.14 (0.61, 2.13) p = 0.48 |
| Change in as-measured 25(OH)D during study—80 nmol/L cutoff | ||||||
| Low all High, then low High all Low, then high Trend: |
32/249.89 (0.13) 4/35.02 (0.11) 7/59.80 (0.12) 17/83.26 (0.20) |
1.00 (reference) 0.93 (0.29, 2.96) 0.94 (0.45, 1.94) 1.61 (0.88, 2.95) p = 0.19 |
1.00 (reference) 0.80 (0.23, 2.77) 0.95 (0.45, 1.98) 1.52 (0.79, 2.90) p = 0.30 |
93/446.95 (0.21) 233/81.08 (0.28) 21/116.29 (0.18) 59/229.44 (0.26) |
1.00 (reference) 1.08 (0.52, 2.26) 0.80 (0.44, 1.47) 1.28 (0.77, 2.14) p = 0.51 |
1.00 (reference) 1.07 (0.57, 2.01) 0.74 (0.42, 1.29) 1.08 (0.70, 1.65) p = 0.99 |
| Change in deseasonalized 25(OH)D during study—50 nmol/L cutoff | ||||||
| Low all High, then low High all Low, then high Trend: |
6/32.84 (0.18) 7/47.73 (0.15) 32/246.29 (0.13) 15/101.11 (0.15) |
1.00 (reference) 0.84 (0.31, 2.29) 0.75 (0.32, 1.78) 0.86 (0.34, 2.13) p = 0.77 |
1.00 (reference) 0.52 (0.19, 1.47) 0.58 (0.25, 1.35) 0.52 (0.19, 1.41) p = 0.35 |
12/73.56 (0.16) 9/72.50 (0.12) 130/505.75 (0.25) 45/221.95 (0.20) |
1.00 (reference) 0.68 (0.28, 1.65) 1.38 (0.69, 2.75) 1.24 (0.60, 2.55) p = 0.30 |
1.00 (reference) 0.78 (0.35, 1.72) 1.26 (0.69, 2.33) 1.09 (0.58, 2.05) p = 0.63 |
| Change in deseasonalized 25(OH)D during study—80 nmol/L cut-off | ||||||
| Low all High, then low High all Low, then high Trend: |
30/225.35 (0.13) 6/34.37 (0.18) 8/66.84 (0.12) 16/101.41 (0.16) |
1.00 (reference) 1.34 (0.53, 3.37) 0.92 (0.45, 1.89) 1.21 (0.66, 2.22) p = 0.65 |
1.00 (reference) 1.36 (0.60, 3.07) 0.83 (0.38, 1.78) 1.03 (0.52, 2.05) p = 0.94 |
100/419.35 (0.24) 25/82.70 (0.30) 23/122.35 (0.19) 48/249.36 (0.19) |
1.00 (reference) 1.04 (0.51, 2.10) 0.73 (0.41, 1.31) 0.84 (0.49, 1.45) p = 0.42 |
1.00 (reference) 0.98 (0.55, 1.75) 0.67 (0.40, 1.11) 0.73 (0.46, 1.15) p = 0.11 |
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.
bAdjusted models for relapse include adjustment for age, sex, and immunomodulatory medication use, and stratified on study site.
UVR, ultraviolet radiation; 25(OH)D, 25-hydroxyvitamin D.