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Table 3 Factors associated with ZPP (μmol/mol haem) measured in erythrocytes a

From: Diagnostic utility of zinc protoporphyrin to detect iron deficiency in Kenyan pregnant women

 

Univariate analysis

Multivariate analysis b

Δ c

(95% CI)

P

Δ c

(95% CI)

P

Gravidity

  

0.13

   

Primigravida

[Reference]

 

  

Secundigravida

23.4%

(–4.3% to 59.2%)

 

  

Multigravida

23.2%

(0.0% to 51.7%)

 

  

Gestational age

  

0.48

   

13–14 weeks

[Reference]

 

  

15–16 weeks

–4.6%

(–29.4% to 29.0%)

 

  

16–18 weeks

13.9%

(–15.3% to 53.2%)

 

  

19–21 weeks

6.1%

(–21.6% to 43.8%)

 

  

22–25 weeks

–5.0%

(–33.1% to 34.8%)

 

  

Anaemia

94.6%

(–67.5% to 126.2%)

<0.001

46.3%

(26.9% to 68.8%)

<0.001

Iron deficiencyd

87.6%

(–62.1% to 117.1%)

<0.001

41.0%

(21.5% to 63.5%)

<0.001

Plasma sTfR concentration, mg/L

48.3%

(–40.0% to 57.1%)

<0.001

34.2%

(25.6% to 43.3%)

<0.001

Plasma transferrin concentration, g/L

85.3%

(–63.2% to 110.4%)

<0.001

15.6%

(0.9% to 32.5%)

0.04

Plasma folate concentration, μg/L

0.6%

(–1.8% to 2.9%)

0.64

24.0%

(3.0% to 49.3%)

0.02

Plasma vitamin B12 concentration, 100pmol/L

–3.5%

(–6.4% to –0.7%)

0.02

  

Plasma total bilirubin concentration, μmol/L

–3.0%

(–4.8% to –1.1%)

0.002

–2.2%

(–3.7% to –0.7%)

0.005

Plasma LDH concentration, 10 IU/L

–0.4%

(–1.2% to 0.3%)

0.21

–0.1%

(–0.2% to 0.0%)

0.003

α +-thalassaemia genotype

  

0.87

   

Normal

[Reference]

 

  

Heterozygote

–5.9%

(–25.2% to 18.3%)

 

  

Homozygote

–4.7%

(–37.9% to 46.2%)

 

  

Plasmodium infection

      

Any Plasmodium spp., by any dipstick or PCR

–3.0%

(–17.5% to 14.1%)

0.71

  

Current or recent P. falciparum infectione

–10.2%

(–26.3% to 9.5%)

0.29

  

P. falciparum, by dipstick,e or PCR

–3.0%

(–17.5% to 14.1%)

0.71

  

P. falciparum, by PCR

–1.4%

(–16.3% to 16.3%)

0.87

  

HIV infection

–8.5%

(–24.6% to 11.0%)

0.37

  

Plasma CRP concentration, mg/L

–0.1%

(–0.6% to 0.5%)

0.82

  

Plasma AGP concentration, g/L

1.4%

(–24.0% to 35.2%)

0.92

  

Inflammationf

      

Plasma CRP concentration ≥10 mg/L

–2.1%

(–18.0% to 16.8%)

0.81

  

Plasma AGP concentration ≥1.0 g/L

3.2%

(–15.8% to 26.5%)

0.76

  

Plasma CRP concentration ≥10 mg/L, or AGP ≥1.0 g/L

–4.2%

(–19.0% to 13.2%)

0.61

  
  1. AGP, α 1-acid glycoprotein; CRP, C-reactive protein; sTfR, Soluble transferrin receptor; ZPP, Zinc protoporphyrin.
  2. aZPP values were normalised by log transformation; exponentiation of results yielded associations being expressed as percentage differences; bThe table shows only results for factors that were independently associated with whole blood ZPP and erythrocyte ZPP; because these final (parsimonious) models were obtained with backward elimination procedures, this resulted in different sets of factors being included for whole blood ZPP and erythrocyte ZPP; cDifference; dPlasma ferritin concentration <15 μg/L; eEither HRP2- or pLDH-based dipstick; fPlasma concentrations of CRP >10 mg/L and/or AGP >1 g/L.