Table 1 Baseline characteristic of studies included in the systematic review and meta-analysis
From: Folate intake, serum folate levels, and prostate cancer risk: a meta-analysis of prospective studies
Study | Country | Study design | Assessment of exposure | Sample size | Age at baseline | Effect estimate | Comparison categories | Follow-up (year) | Covariates in fully adjusted model |
|---|---|---|---|---|---|---|---|---|---|
SJ Weinstein8 2006 | Finland | Cohort | FFQ | 27111 | 50-69 | RR | >378 μg/d versus <283 μg/d | 12.4 | Age, vitamin supplement use, energy intake |
VL Stevens9 2006 | US | Cohort | FFQ | 65836 | 50-74 | RR | >347 μg/d versus <204 μg/d | 9.0 | Age, race, education, total calories, total calcium, ethanol, family history of prostate cancer, vitamin B12, prostate-specific antigen screening, and history of diabetes |
JK Bassett10 2012 | Australia | Cohort | FFQ | 14620 | 40-69 | HR | 444 μg/d versus 215 μg/d | 15.0 | Country of birth, education, alcohol consumption, BMI, and daily intakes of lycopene and calcium |
BAJ Verhage11 2012 | Netherland | Cohort | FFQ | 58279 | 55-69 | HR | >259.1 μg/d versus <176.5 μg/d | 17.3 | Age |
N Roswall12 2013 | Denmark | Cohort | Self-administer questionnaire | 26856 | 50-64 | HR | >412.9 μg/d versus <280.5 μg/d | 17.0 | Intake of the three other micronutrients as well as dietary intake for the supplemental intake and supplemental intake for the dietary intake and further for height, weight, education, intake of red meat, alcohol consumption, selenium intake |
M Johansson13 2008 | Europe | Nest case control | Blood samples | 2043 | 58.7 | RR | >16.55 nmol/L versus <4.82 nmol/L | 5.0 | Body mass index, smoking status, alcohol intake, physical activity, marital status, and education level |
J Beilby14 2010 | Australia | Nest case control | Blood samples | 321 | 69.5 | OR | Tertiles 3 versus tertiles 1 | 6.0 | Age, administered vitamin A supplement |
S Vogel15 2013 | Norway | Nest case control | Blood samples | 6000 | 49.1 | OR | >17.5 nmol/L versus <10.9 nmol/L | 15.7 | Serum creatinine concentration, education, smoking, physical activity and body mass index. |
J Hultdin7 2005 | Sweden | Nest case control | Blood samples | 768 | 58.2 | OR | >10.3 nmol/L versus <5.85 nmol/L | 4.9 | Other 2 plasma variables, BMI and smoking |
SJ Weinstein16 2003 | Finland | Nest case control | Blood samples | 678 | 50-69 | OR | >10.79 nmol/L versus <6.87 nmol/L | 6-9 | Benign prostate hyperplasia |