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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)