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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

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

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

 
  1. *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.
  2. **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.
  3. *Significantly different than ≥ 2 h/d (P = 0.004).
  4. **Significantly different than > once/d (P<0.0001).
  5. #Significantly different than ≥ 30 kg/m2 (P<0.0001).
  6. ##Significantly different than 49–54oN (P = 0.01).