Table 1.
Systematic review study characteristics
| Author and year | Study name and location | Study design | Cases | Total N (cohorts) or controls or sub-cohort | Years of follow-up | Sex (% men) | Age range (at baseline for cohorts) | Exposures measured | Outcome | Adjusted covariates | Statistic | NOS score |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Arendt 2013 | Denmark | Cohort | 445 | 333,667 | Median 3.5 | 41% | IQR 40.2–69.2 | Plasma B12 | Kidney | Age, sex, calendar year | SIR | 4.0 |
| Aune 2010 | Uruguay | Case–control | 114 | 2032 | N/A | 66% |
23–89 (cases) 22–89 (controls) |
Dietary B9 | Kidney | Age, sex, BMI, smoking, alcohol, energy intake, calcium, iron, fibre, mate drinking, intake of vitamins B6, C, and E, and carotenoids, education, income, urban/rural residence, interviewer | OR | 6.0 |
| Bock 2018 | The US Kidney Cancer Study (USA) | Case–control | 1142 | 1154 | N/A | 55% | 20–79 | Dietary B1, B2, B3, B6, B9, B12 | RCC | Age, sex, BMI, smoking, alcohol, energy intake, hypertension, family history, education, region, race | OR | 6.0 |
| Bosetti 2006 | Italy | Case–control | 767 | 1534 | N/A | 64% |
24–79 (cases) 22–79 (controls) |
Dietary B1, B2, B3, B6, B9 | RCC | Age, sex, BMI, smoking, alcohol, family history, education, centre, period of interview | OR | 8.0 |
| Brock 2012 | Iowa, USA | Case–control | 323 | 1827 | N/A | 67% | 40–85 | dietary B9 | RCC | Age, sex, BMI at age 40, smoking, alcohol, energy intake, fatty spreads consumption, hypertension, proxy status | OR | 7.0 |
| Cho 2013 | NHS (USA) | Cohort | 225 | 77,208 | 24 | 0% | 30–55 | Total intake B6, B9, B12, methionine | RCC | Age, BMI, smoking, alcohol, energy intake, fruit and vegetable consumption, hypertension, diabetes, parity calendar time | RR | 5.5 |
| Cho 2013 | HPFS (USA) | Cohort | 211 | 47,886 | 22 | 100% | 40–75 | Total intake B6, B9, B12, methionine | RCC | Age, BMI, smoking, alcohol, energy intake, fruit and vegetable consumption, hypertension, diabetes, calendar time | RR | 5.5 |
| Gibson 2010 | ATBC (Finland) | Nested case–control | 224 | Not reported | Not reported | 100% | 50–69 | Serum B2, B6, B9 B12, homocysteine | RCC | All nutrients: age, BMI and smoking; B9 only: protein and fat intake; B6, B2, and homocysteine only: serum B9; B12 only: protein, leisure time physical activity and serum B9; alcohol checked but not included as not found to be a confounder | OR | 7.0 |
| Hu 2003 | NECSS (Canada) | Case–control | 1110 | 4708 | N/A | 51% | 20–70+ | B-complex supplements | RCC | Age, BMI, smoking, alcohol, education, province | OR | 7.0 |
| Johansson 2014 | EPIC (Europe) | Nested case–control | 556 | 556 matched; 553 unmatched | Not reported | Matched 56%; unmatched 68% | Not reported | Plasma B2, B6, B9, B12, methionine, homocysteine | RCC | Age, sex, waist-to-hip ratio, smoking, plasma cotinine, alcohol, hypertension, education, country | OR | 8.5 |
| Johansson 2014 | MCCS (Australia) | Nested case–control | 144 | 144 | Not reported | Both, % men not specified | 40–79 | Plasma B6 | RCC | Age, sex, waist-to-hip ratio, smoking, plasma cotinine, alcohol, hypertension, education, country | OR | 9.0 |
| Nicodemus 2004 | Iowa Women's Health Study (USA) | Cohort | 124 | 34,637 | 15 | 0% | 55–69 | Dietary B1, B2, B6 | Kidney | Age | RR | 5.0 |
| Prineas 1997 | Iowa Women's Health Study (USA) | Cohort | 62 | 35,192 | 8 | 0% | 55–69 | Dietary B1, B2, B6 | RCC | Age | RR | 4.0 |
| Schouten 2016 | NLCS (The Netherlands) | Case–cohort | 498 | 3980 | 20.3 | 49% | 55–69 | Dietary B9 | RCC | Age, sex, BMI, smoking, alcohol, energy intake, intake of methionine and B2 and B6, hypertension | HR | 8.0 |
| Tavani 2012 | Italy | Case–control | 767 | 1534 | N/A | 64% | Not reported | Dietary B9 | Kidney | Age, sex, BMI, smoking, alcohol, energy intake, education, study centre, year of interview, physical activity at work | OR | 5.0 |
NHS, Nurses’ Health Study; HPFS, The Health Professionals Follow-up Study; ATBC, Alpha-Tocopherol Beta-Carotene Cancer Prevention Study; NECSS, National Enhanced Cancer Surveillance System; EPIC, European Prospective Investigation into Cancer and Nutrition; MCCS, Melbourne Collaborative Cohort Study; NLCS, The Netherlands Cohort Study on Diet and Cancer