TABLE 3.
Summary of articles and effect estimates as included in meta-analysis on circulating magnesium and risk of CAD1
| Study | Design | Follow-up, y | n total | n events or cases | Exposure assessment method | Exposure categorization2 | Outcome assessment | HR or RR3 (95% CI), low vs. high category | Covariate adjustments |
|---|---|---|---|---|---|---|---|---|---|
| ARIC study (current research) | Cohort | 30 | 14,446 | 2131 | Serum; metallo-chromic dye calmagite | Quintiles (mEq/L): Q1 0.60–1.50 (ref); Q2 1.55–<1.60; Q3 1.60–<1.70; Q4 1.70–<1.75; Q5 1.75–2.35 | Incident CAD = medical records; death certificates with next-of-kin interviews and physician questionnaire | HR Q1 vs. Q5: 1.28 (1.11, 1.47) | Age, sex, race-center, baseline BMI, education, physical activity, drinking status, ethanol intake (grams per week), smoking status, pack-years of smoking, diabetes, HDL cholesterol, total cholesterol, lipid-lowering medication use, SBP, antihypertensive medication use, eGFR, hormone therapy use (in women only) |
| NHANES Follow-up (13) | Cohort | 19 | 12,340 | 2637 | Serum; atomic absorption spectrophotometry | Quartiles (mEq/L): Quartile 1 <1.59 (ref); Quartile 2 1.59–<1.68; Quartile 3 1.68–<1.77; Quartile 4 ≥1.77 | Incident IHD = hospital records (ICD-9-CM codes 410–414) | HR* Q1 vs. Q4: 1.09 (0.93, 1.26) | Age, gender, race, education, smoking, serum cholesterol, SBP, antihypertensive medication, self-reported diabetes, BMI, leisure- and nonleisure time physical activity, alcohol consumption |
| PREVEND study (14) | Cohort | 11 | 6595 | 435 | Plasma; xylidyl blue | Quintiles (mmol/L): Q1 <0.77; Q2 0.77–0.79; Q3 0.80–0.82 (ref); Q4 0.83–0.85; Q5 >0.85 | Incident IHD = acute myocardial infarction (ICD-10 code I21), hospitalization for other acute IHD (I24), coronary artery bypass grafting, or percutaneous transluminal coronary angioplasty | HR Q1 vs. Q3: 1.06 (0.79, 1.43) | Age; smoking status; sex; BMI; ratio of total to HDL cholesterol; parental history of IHD; alcohol consumption; plasma calcium, sodium, and potassium concentrations |
| Framingham Offspring study (15) | Cohort | 20 | 3531 | 554 | Serum; colorimetric assay | Quartiles (mmol/L): Quartile 1 0.41–<0.80; Quartile 2 0.80–<0.84; Quartile 3 0.84–<0.89; Quartile 4 0.89–1.45 | Incident CVD = angina pectoris, coronary insufficiency, MI, stroke or TIA, HF, intermittent claudication, or death secondary to CVD | HR* Q1 vs. Q4: 1.10 (0.86, 1.40) | Age, sex, BMI, diabetes, SBP, total:HDL cholesterol, smoking, hemoglobin, albumin, eGFR |
| Nurses’ Health Study (16) | Nested case-control | n/a | 916 | 458 | Plasma; colorimetric assay | Quartiles (mg/dL): Quartile 1 ≤2.0; Quartile 2 2.1–2.1; Quartile 3 2.2–2.3; Quartile 4 ≥2.4 | Incident CAD = nonfatal MI (WHO criteria) or fatal CAD (autopsy or hospital records or primary cause of death) | RR* Q1 vs. Q4: 1.64 (1.04, 2.59) | Matching factors (age, smoking status, month of blood draw, fasting status), BMI, exercise, alcohol intake, family history of MI, eGFR, menopausal therapy, multivitamin use, intake of omega‐3 fats, polyunsaturated:saturated fat ratio, trans fat, dietary cholesterol, cereal fiber, calcium, potassium, vitamin D |
Study quality assessed using the Newcastle-Ottawa Scale (24): NHANES Follow-up = 9; PREVEND study = 9; Framingham Offspring study = 9; Nurses’ Health Study = 9. ARIC, Atherosclerosis Risk in Communities; CAD, coronary artery disease; CVD, cardiovascular disease; eGFR, estimated glomerular filtration rate; HF, heart failure; ICD, International Classification of Diseases; IHD, ischemic heart disease; MI, myocardial infarction; n/a, not applicable; PREVEND, Prevention of Renal and Vascular End-Stage Disease; SBP, systolic blood pressure; TIA, transient ischemic attack.
To convert magnesium (milliequivalents per liter) to millimoles per liter or milligrams per deciliter, multiply by 0.5 and by 1.22, respectively.
HR* or RR* indicates that we inverted (23) the published HR or RR and corresponding 95% CI such that the highest category became the referent group to be consistent with the ARIC analyses.