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Table 3 Multivariable linear regression for square root transformed 25(OH)D weighted for the household population aged 12 to 79 years, Canada, 2007 to 2009

From: Solar ultraviolet-B radiation and vitamin D: a cross-sectional population-based study using data from the 2007 to 2009 Canadian Health Measures Survey

Variable

β* ± SE

Mean 25(OH)D**

P

Partial

 

(95% CI)

 

r2***

91-Day UV-B

0.04 ± 0.01

0.5 (0.3, 0.8)

0.0001

0.03

Sex

   

0.01

 Female

(Reference)

54.2 (49.6, 58.9)

  

 Male

−0.31 ± 0.05

49.8 (48.3, 51.3)

< 0.0001

 

Age

   

0.01

 12-19 years

−0.13 ± 0.10

52.3 (49.6, 55.0)

0.16

 

 20-59 years

(Reference)

54.2 (49.6, 58.9)

  

 60-79 years

0.36 ± 0.09

59.6 (56.8, 62.4)

0.0001

 

Ethnicity

   

0.06

 White

(Reference)

54.2 (49.6, 58.9)

  

 Non-White

−1.10 ± 0.12

39.3 (36.5, 42.1)

< 0.0001

 

Sun Exposure

   

0.01

 < 30 min/d

(Reference)

54.2 (49.6, 58.9)

  

 ≥ 30 min/d and < 2 h/d

0.22 ± 0.07*

57.5 (55.4, 59.6)

0.002

 

 ≥ 2 h/d

0.42 ± 0.09

60.5 (57.7, 63.4)

< 0.0001

 

Vitamin D Supplementation

   

0.01

 No

(Reference)

54.2 (49.6, 58.9)

  

 Yes

0.44 ± 0.06

60.8 (59.1, 62.6)

< 0.0001

 

Milk Consumption

   

0.02

 < Once/d

(Reference)

54.2 (49.6, 58.9)

  

 Once/d

0.29 ± 0.05**

58.6 (57.0, 60.2)

< 0.0001

 

 > Once/d

0.58 ± 0.06

63.1 (61.3, 64.9)

< 0.0001

 

Body Mass Index

   

0.02

 < 25 kg/m2

(Reference)

54.2 (49.6, 58.9)

  

 ≥ 25 and < 30 kg/m2

−0.13 ± 0.07#

52.2 (50.3, 54.2)

0.05

 

 ≥ 30 kg/m2

−0.63 ± 0.05

45.3 (44.0, 46.7)

< 0.0001

 

Physical Activity Index

   

0.01

 Inactive

(Reference)

54.2 (49.6, 58.9)

  

 Moderately Active

0.30 ± 0.08

57.1 (55.4, 58.8)

0.0009

 

 Active

0.19 ± 0.06

58.6 (56.3, 61.1)

0.0002

 
  1. Model r2 = 0.21.
  2. *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.
  3. **For 9-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.
  4. ***Total variance in square root transformed 25(OH)D explained by each predictor, controlling for all other variables.
  5. *Significantly different than ≥ 2 h/d (P = 0.003).
  6. **Significantly different than > once/d (P<0.0001).
  7. #Significantly different than ≥ 30 kg/m2 (P<0.0001).