Table 2.
Simple linear regression for square root transformed 25(OH)D weighted for the household population aged 12 to 79 years, Canada, 2007 to 2009
|
Variable |
β* ± SE |
25(OH)D** |
P |
Model |
|
|---|---|---|---|---|---|
| (95% CI) | r2 | ||||
| 91-Day UV-B (kJ /m2) |
0.04 ± 0.01 |
0.6 (0.2, 0.9) |
0.0002 |
0.03 |
|
| Sex |
|
|
|
0.01 |
|
| Female |
(Reference) |
67.1 (65.0, 69.1) |
|
|
|
| Male |
−0.30 ± 0.07 |
62.3 (60.1, 64.4) |
< 0.0001 |
|
|
| Age |
|
|
|
0.01 |
|
| 12-19 years |
0.14 ± 0.10 |
65.4 (62.3, 68.5) |
0.16 |
|
|
| 20-59 years |
(Reference) |
63.2 (60.6, 65.9) |
|
|
|
| 60-79 years |
0.41 ± 0.10 |
69.8 (66.7, 73.1) |
< 0.0001 |
|
|
| Ethnicity |
|
|
|
0.09 |
|
| White |
(Reference) |
68.4 (64.3, 72.8) |
|
|
|
| Non-White |
−1.27 ± 0.13 |
49.0 (46.0, 52.1) |
< 0.0001 |
|
|
| Sun Exposure |
|
|
|
0.01 |
|
| < 30 min/d |
(Reference) |
58.9 (55.9, 61.9) |
|
|
|
| ≥ 30 min/d and < 2 h/d |
0.34 ± 0.10* |
64.2 (61.2, 67.2) |
0.0003 |
|
|
| ≥ 2 h/d |
0.52 ± 0.09 |
67.0 (64.4, 69.7) |
< 0.0001 |
|
|
| Sunscreen Use |
|
|
|
0.01 |
|
| Never or rarely |
(Reference) |
64.1 (61.6, 66.6) |
|
|
|
| Sometimes |
0.11 ± 0.07 |
65.9 (63.8, 68.1) |
0.09 |
|
|
| Often or always |
0.32 ± 0.07 |
69.3 (67.0, 71.6) |
< 0.0001 |
|
|
| Vitamin D Supplementation |
|
|
|
0.01 |
|
| No |
(Reference) |
63.6 (61.1, 66.1) |
|
|
|
| Yes |
0.41 ± 0.13 |
70.2 (66.0, 74.6) |
0.002 |
|
|
| Milk Consumption |
|
|
|
0.03 |
|
| < Once/d |
(Reference) |
60.0 (57.8, 62.2) |
|
|
|
| Once/d |
0.36 ± 0.06** |
65.7 (63.9, 67.6) |
< 0.0001 |
|
|
| > Once/d |
0.75 ± 0.06 |
72.1 (70.1, 74.1) |
< 0.0001 |
|
|
| Salt Water Fish Consumption |
|
|
|
< 0.01 |
|
| < Once/week |
(Reference) |
63.8 (60.9, 66.8) |
|
|
|
| Once/week |
0.04 ± 0.08 |
64.5 (62.0, 67.0) |
0.60 |
|
|
| > Once/week |
0.17 ± 0.16 |
66.6 (61.7, 71.7) |
0.27 |
|
|
| Body Mass Index |
|
|
|
0.02 |
|
| < 25 kg/m2 |
(Reference) |
67.2 (64.1, 70.5) |
|
|
|
| ≥ 25 and < 30 kg/m2 |
−0.07 ± 0.08# |
66.1 (63.7, 68.6) |
0.38 |
|
|
| ≥ 30 kg/m2 |
−0.57 ± 0.09 |
58.2 (55.6, 60.8) |
< 0.0001 |
|
|
| Physical Activity Index |
|
|
|
0.02 |
|
| Inactive |
(Reference) |
60.8 (58.3, 63.4) |
|
|
|
| Moderately Active |
0.46 ± 0.07 |
68.2 (65.9, 70.6) |
< 0.0001 |
|
|
| Active |
0.54 ± 0.11 |
69.6 (66.1, 73.2) |
< 0.0001 |
|
|
| Cigarette Smoking |
|
|
|
< 0.01 |
|
| Non-Smoker |
(Reference) |
65.3 (63.0, 67.6) |
|
|
|
| Current Smoker |
−0.19 ± 0.12 |
62.3 (58.8, 65.9) |
0.10 |
|
|
| Alcohol Use |
|
|
|
0.01 |
|
| Non-Drinker |
(Reference) |
60.4 (56.7, 64.2) |
|
|
|
| Current Drinker |
0.33 ± 0.10 |
65.6 (62.6, 68.7) |
0.0006 |
|
|
| Season |
|
|
|
0.03 |
|
| January to March |
(Reference) |
58.6 (48.1, 70.0) |
|
|
|
| April to June |
0.36 ± 0.41 |
64.2 (51.9, 77.8) |
0.38 |
|
|
| July to September |
0.85 ± 0.42 |
72.2 (58.9, 87.0) |
0.04 |
|
|
| October to December |
0.38 ± 0.39 |
64.6 (52.8, 77.5) |
0.33 |
|
|
| Latitude |
|
|
|
0.02 |
|
| 43-44oN |
(Reference) |
63.0 (59.3, 66.7) |
|
|
|
| 45-47oN |
0.43 ± 0.24## |
70.0 (62.4, 78.1) |
0.07 |
|
|
| 49-54oN | −0.09 ± 0.12 | 61.5 (57.8, 65.3) | 0.44 |
*For 91-day UV-B, the estimated mean increase in square root transformed 25(OH)D for a 1 kJ/m2 increase in solar UV-B irradiance between 11 am and 4 pm at the CHMS collection sites averaged over the 91-days prior to blood draw; for other predictors, the estimated mean change in square root transformed 25(OH)D compared to the reference category.
**For 91-day UV-B, the estimated mean increase in back transformed 25(OH)D (nmol/L) for a 1 kJ/m2 increase in solar UV-B irradiance between 11 am and 4 pm at the CHMS collection sites averaged over the 91-days prior to blood draw; for other predictors,, the estimated mean change in back transformed 25(OH)D (nmol/L) compared to the reference category.
*Significantly different than ≥ 2 h/d (P = 0.004).
**Significantly different than > once/d (P<0.0001).
#Significantly different than ≥ 30 kg/m2 (P<0.0001).
##Significantly different than 49–54oN (P = 0.01).