Table 3. Characteristics of studies included in the meta-analysis.
| Source | Participants (n) | Follow-up (years) | Person-years of follow-up | No of cases | Age at baseline (years) | Male (%) | Exposure assessment | Exposure categories | Outcome assessment | Adjusted variables | Measures of association |
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Cohort studies | |||||||||||
| Dibaba TD, 2014, USA | 66 806 | 6.8 | 451 560 | 151 | 50–76 | 49.5 | 120-item FFQ, plus supplement use | Three groups based on RDA: <75% RDA; 75–99% RDA; ⩾100% RDA | Pancreatic adenocarcinoma was identified based on the International Classification of Disease for Oncology, 3rd edition (ICD-O-3) | Age, gender, ethnicity, education, BMI, physical activity, smoking (pack-years smoked), alcohol intake, diabetes, family history of pancreatic cancer, NSAID use, and intakes of calcium, selenium, omega-3 fatty acids, and calories | HR (95% CIs) for total magnesium intake: highest versus lowest: 0.569 (0.338, 0.960). Per 100 mgper day increase: 0.806 (0.667, 0.980) |
| Molina-Montes et al, 2012, Europe | 477 202 | 11.3 | 1 591 205 (men); 3 671 100 (women) | 865 (396 in men and 469 in women) | 25–70 | 29.8 | Country-specific FFQ were used | Quintiles of energy-adjusted magnesium intake (mg per day) <292.9; 292.9–329.8; 329.9–360.8; 360.9–399.9; >399.9 | Linkage with regional or national population-based cancer registries and national mortality registries (ICD-O-3 was used) | Energy intake from fat source, energy intake from non-fat sources, smoking, height, weight, and self-reported diabetes | HR (95% CIs) for energy-adjusted magnesium intake: highest versus lowest: 0.84 (0.65, 1.10). Per 100 mg per day increase: 1.00 (0.82, 1.22) |
| Kesavan et al, 2010, USA | 47 893 | 20 | 851 476 | 300 | 40–75 | 100.0 | Semiquantitative FFQ was used, plus supplement and multivitamin use | Quintiles of total magnesium intake (median, mg per day) 263; 307; 343; 384; 457 | Self-report, and medical record with confirmed with complete histology | Age, BMI, height, history of diabetes (yes/no), physical activity (quintiles of metabolic equivalent task hours per week), smoking history (categories), total caloric intake (quintiles) | RR (95% CIs) for total magnesium intake: 0.94 (0.66, 1.32) |
Abbreviations: BMI=body mass index; CI=confidence interval; FFQ=food frequency questionnaire; HR=hazard ratio; ICD-O-3=International Classification of Disease 3rd edition, NA=not available; NSAIDs=non-steroidal anti-inflammatory drugs; OR=odds ratio; RDA=recommended dietary allowance; RR=relative risk; T=tertile.