Vitamin D deficiency and the risk of anemia: a meta-analysis of observational studies

Figures & data

Figure 1. Flow chart of study selection.

Table 1. Baseline characteristics of the included studies.

Study	Country	Study period	Study design	Sample size	Age
Sim et al.16 2010	USA	2004–2006	Cross-sectional	554	65 years
Perlstein et al.17 2011	USA	1991–1994	Cohort	2610	≥60 years
Yoo et al.18 2012	Korea	NA	Case-control	447	19–91 years
Chang et al.19 2013	China	Jan–Dec 2011	Cross-sectional	884	6 months–14 years
Coutard et al.20 2013	France	Jan–Aug 2011	Case-control	186	85 years
Golbahar et al.21 2013	Bahrain	2010–2011	Cross-sectional	420	18–60 years
Jin et al.22 2013	Korea	Aug 2010–Jul 2011	Case-control	82	3 and 24 months
Study	VDD diagnostic criteria	Definition of anemia	Variable adjustment	Study quality
Sim et al.16 2010	<30 ng/mL	Hb <11 g/dL	Age, gender, ESA use, eGFR <60 mL/min/1.73 m^2	6
Perlstein et al.17 2011	<20 ng/mL	Male: Hb <13 g/dL	Age, gender, ethnicity	7
		Female: Hb <12 g/dL
Yoo et al.18 2012	<20 ng/mL	Male: Hb <13 g/dL	Age, gender	5
		Female: Hb <12 g/dL
Chang et al.19 2013	<20 ng/mL	Hb <11 g/dL (0.5–4.99 years)	Age, gender, season of blood sampling	5
		Hb <11.5 g/dL (5–11.99 years)
		Hb <12.0 g/dL (12–14 years)
Coutard et al.20 2013	<20 ng/mL	Male: Hb <13 g/dL	Gender, albuminemia, EPO level	6
		Female: Hb <12 g/dL
Golbahar et al.21 2013	<30 ng/mL	Male: Hb <13 g/dL	Age, calcium, hemoglobin, PTH levels	5
		Female: Hb <12 g/dL
Jin et al.22 2013	<20 ng/mL	Hb ≤11 g/dL	Age, gender, season, serum iron level, breastfeeding	6

Note: NA = not available, ESA = erythrocyte-stimulating agents, PTH = parathyroid hormone, EPO = erythropoietin, eGFR = estimated glomerular filtration rate.

Figure 2. Forest plot showing risk estimates from our included studies estimating the association between VDD and risk for anemia.

Table 2. Summary of pooled odds ratios for association between VDD and anemia.

Subgroup	Number of studies	Pooled OR (95% CI)	Q-test for heterogeneity p value (I^2)
Geographical region
Asia	4	2.04 (1.07, 3.86)	0.001 (82.9%)
United States	2	1.60 (1.31, 1.95)	0.623 (0.0%)
Europe	1	11.62 (4.93, 27.35)	–
Study design
Case-control study	3	3.98 (0.91, 17.43)	0.000 (91.6%)
Cross-sectional study	3	1.87 (1.08, 3.23)	0.005 (80.8%)
Cohort study	1	1.54 (1.21, 1.97)	–
Age
Adults	5	2.33 (1.43, 3.80)	0.000 (86.7%)
Children	2	2.24 (0.54, 9.29)	0.009 (85.5%)
VDD diagnostic criteria
<20 ng/mL	5	2.31 (1.26, 4.25)	0.000 (86.2%)
<30 ng/mL	2	2.32 (1.26, 4.29)	0.022 (81.0%)

Figure 3. Results of sensitivity analysis for the current meta-analysis.

Figure 4. Begg’s funnel plot for publication bias evaluating the association between VDD and anemia.

Sim JJ, Lac PT, Liu IL, et al. Vitamin D deficiency and anemia: A cross-sectional study. Ann Hematol. 2010;89:447–452

 PubMed Web of Science ®Google Scholar

Perlstein TS, Pande R, Berliner N, Vanasse GJ. Prevalence of 25-hydroxyvitamin D deficiency in subgroups of elderly persons with anemia: Association with anemia of inflammation. Blood. 2011;117:2800–2806

 PubMed Web of Science ®Google Scholar

Yoo EH, Cho HJ. Prevalence of 25-hydroxyvitamin D deficiency in Korean patients with anemia. Blood. 2012;120:21

 Google Scholar

Chang L, Liu X, Shi H, Dai W, Wang H, Jiang Y. Association of 25-hydroxyvitamin D with Hb and lead in children: A Chinese population-based study. Public Health Nutr. 2014;17: 827–832

 PubMed Web of Science ®Google Scholar

Coutard A, Garlantezec R, Estivin S, Andro M, Gentric A. Association of vitamin D deficiency and anemia in a hospitalized geriatric population: Denutrition as a confounding factor. Ann Hematol. 2013;92:615–619

 PubMed Web of Science ®Google Scholar

Golbahar J, Altayab D, Carreon E, Darwish A. Association of vitamin D deficiency and hyperparathyroidism with anemia: A cross-sectional study. J Blood Med. 2013;4:123–128

 Google Scholar

Jin HJ, Lee JH, Kim MK. The prevalence of vitamin D deficiency in iron-deficient and normal children under the age of 24 months. Blood Res. 2013;48:40–45

 Google Scholar