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Table 2 Environmental factors are associated with vitamin D status

From: Prevalence and predictors of vitamin D deficiency in young African children

 

25(OH)D levels (nmol/L)a

Unadjusted regression analyses of 25(OH)D levels

Adjusted regression analyses of 25(OH)D levels

Adjusted logistic regression analyses 25(OH)D < 50 nmol/L

Medians (IQR)

Means (95% CI)

Beta (95% CI)

P

R2

Beta (95% CI)

P

OR (95% CI)

P

Age in years

-

-

− 0.05 (− 0.06, − 0.04)

< 0.0001

0.045

− 0.07 (− 0.08, − 0.07)

< 0.0001

1.69 (1.52, 1.89)

< 0.0001

Sex

 Males

77.7 (64.1, 94.5)

77.50 (76.52, 78.49)

Ref.

–

 

Ref.

–

Ref.

–

 Females

77.2 (63.0, 94.0)

76.45 (75.43, 77.48)

− 0.01 (− 0.03, 0.01)

0.15

0.0005

− 0.02 (− 0.03, 0.001)

0.066

1.32 (1.04, 1.68)

0.021

Country

 Kenya

81.0 (66.3, 101.6)

81.85 (80.42, 83.30)

Ref.

–

 

Ref.

–

Ref.

–

 Uganda

78.6 (65.1, 94.5)

78.27 (77.02, 79.54)

− 0.04(− 0.07, − 0.02)

0.0002

0.029

0.01 (− 0.02, 0.03)

0.51

0.50 (0.34, 0.74)

0.001

 Burkina Faso

78.4 (64.5, 91.3)

77.26 (74.98, 79.61)

− 0.06 (− 0.10, − 0.02)

0.003

 

− 0.05 (− 0.08, − 0.01)

0.012

0.81 (0.45, 1.44)

0.47

 The Gambia

71.2 (59.1, 84.2)

72.78 (71.15, 74.45)

− 0.15 (− 0.18, − 0.12)

< 0.0001

 

0.09 (0.05, 0.13)

< 0.0001

0.29 (0.17, 0.47)

< 0.0001

 South Africa

76.2 (60.6, 91.9)

70.39 (68.95, 71.86)

− 0.12 (− 0.14, − 0.09)

< 0.0001

 

− 0.15 (− 0.18, − 0.12)

< 0.0001

2.89 (1.94, 4.29)

< 0.0001

Seasonb

 Summer/short rains/dry

78.8 (64.8, 95.8)

78.77 (77.19, 80.39)

Ref.

–

 

Ref.

–

Ref.

–

 Autumn/dry

83.6 (67.1, 101.1)

82.72 (81.43, 84.02)

0.05 (0.02, 0.07)

0.0002

0.038

0.03 (0.01, 0.06)

0.014

0.65 (0.40, 0.96)

0.032

 Winter/long rains

73.3 (60.1, 87.0)

71.14 (69.96, 72.34)

− 0.10 (− 0.13, − 0.08)

< 0.0001

 

− 0.10 (− 0.12, − 0.07)

< 0.0001

2.55 (1.75, 3.72)

< 0.0001

 Spring/dry

76.3 (63.1, 91.4)

75.18 (73.55, 76.84)

− 0.05 (− 0.08, − 0.02)

0.002

 

− 0.05 (− 0.08, − 0.02)

0.002

1.60 (1.07, 2.38

0.022

Stuntingc

 Not stunted

77.1 (63.7, 91.0)

76.13 (75.08, 77.19)

Ref.

–

 

Ref.

–

Ref.

–

 Stunted

73.1 (61.2, 88.4)

73.58 (71.89, 75.31)

− 0.03 (− 0.06, − 0.01)

0.015

0.003

− 0.01 (− 0.04, 0.01)

0.34

1.05 (0.69, 1.58)

0.82

Underweightd

 Not underweight

77.2 (63.8, 91.7)

76.67 (75.72, 77.64)

Ref.

–

 

Ref.

–

Ref.

–

 Underweight

75.6 (61.9, 91.3)

74.90 (72.68, 77.18)

− 0.02 (− 0.06, 0.01)

0.15

0.0008

− 0.004 (− 0.04, 0.03)

0.81

0.88 (0.54, 1.40)

0.58

Wastinge>

 Not wasted

76.0 (62.9, 90.6)

75.32 (74.40, 76.26)

Ref.

–

 

Ref.

–

Ref.

–

 Wasted

79.2 (63.6, 94.5)

77.81 (74.45, 81.32)

0.03 (− 0.02, 0.08)

0.19

0.0008

0.04 (− 0.01, 0.08)

0.12

0.64 (0.29, 1.38)

0.25

Inflammationf

 Without inflammation

76.4 (62.7, 92.3)

75.53 (74.74, 76.3)

Ref.

–

 

Ref.

–

Ref.

–

 With inflammation

81.9 (68.0, 99.5)

82.11 (80.55, 83.69)

0.08 (0.06, 0.11)

< 0.0001

0.012

0.07 (0.05, 0.09)

< 0.0001

0.59 (0.43, 0.81)

0.001

Malariag

 Without malaria

77.1 (63.1, 92.4)

76.01 (75.26, 76.77)

Ref.

–

 

Ref.

–

Ref.

–

 With malaria

71.3 (58.9, 85.4)

71.63 (69.68, 73.63)

− 0.06 (− 0.09, − 0.03)

0.0001

0.004

− 0.04 (− 0.07, − 0.01)

0.02

1.02 (0.65, 1.61)

0.93

  1. Correlation coefficients and p values were obtained from linear regression analyses and odds ratios from logistic regression analyses. 25(OH)D levels were ln-transformed in linear regression analyses to make them normally distributed. Covariates in the multivariable linear regression models included age, sex, season, inflammation and study site, as appropriate
  2. 25(OH)D 25-hydroxyvitamin D, n/a not available, OR odds ratio, 95% CI 95% confidence interval
  3. aMedians (IQR) and geometric means are presented.bSeason was based on 3 monthly intervals. In South Africa, the seasons were summer, autumn, winter and spring; in Uganda and Kenya, there are two rainy seasons; and in Burkina Faso and The Gambia, there is a single rainy season. cStunting was defined as height-for-age Z score < − 2; dunderweight as weight-for-age Z score < − 2; ewasting as weight-for-height Z score < − 2; finflammation as CRP > 5 mg/L or ACT > 0.6 g/L and gmalaria as presence of P. falciparum parasites on blood film. Analyses by country are presented in Additional file 4: Table S3 (logistic regression) Additional file 5: Table S4 (unadjusted linear regression), and Additional file 6: Table S5 (adjusted linear regression)
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