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Table 1 Summary characteristics of studies included in the analysis of vitamin D deficiency and risk of AD

From: Vitamin D deficiency is associated with increased risk of Alzheimer’s disease and dementia: evidence from meta-analysis

References Year Country Study type Participants Average age (years) OR 95 % CI 25(OH)D (nmol/L) Adjustment
Afzal [10] 2014 Denmark Prospective cohort 2384 - 1.25 0.95–1.64 <25 Age, sex, month of blood sample, smoking status, body mass index, leisure time and work-related physical activity, alcohol consumption, income level, education, baseline diabetes mellitus, hypertension, cholesterol, high-density lipoprotein cholesterol, and creatinine
Afzal [10] 2014 Denmark Prospective cohort 4087 - 1.12 0.90–1.4 25–50 Age, sex, month of blood sample, smoking status, body mass index, leisure time and work-related physical activity, alcohol consumption, income level, education, baseline diabetes mellitus, hypertension, cholesterol, high-density lipoprotein cholesterol, and creatinine
Littlejohns [9] 2014 UK Prospective cohort 1615 73.6 ± 4.5 2.22 1.02–4.83 <25 Age, season of vitamin D collection, education, sex, BMI, smoking, alcohol consumption, and depressive symptoms
Littlejohns [9] 2014 UK Prospective cohort 1615 73.6 ± 4.5 1.69 1.06–2.69 25–50 Age, season of vitamin D collection, education, sex, BMI, smoking, alcohol consumption, and depressive symptoms
Buell [12] 2010 USA Cross-sectional 318 73.5 ± 8.1 2.65 0.99–7.16 ≤50 Age, race, sex, body mass index, and education, kidney function, multivitamin use, season, diabetes, hypertension, plasma homocysteine, and ApoE allele status