Table 1.
Risk and protective factors of sudden cardiac death, in meta-analyses of observational studies.
| Reference | Risk/Protective factor | Exposed/Unexposed as in included MA | Protective/Risk factor or intervention | K | n/N | Metric | ES (95% CI) | p-value | PI include null value | I2 | SSE | ESB | LS sign | CE | CES | CES2 (n > 1,000) | AMSTAR 2 Quality |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| General population | |||||||||||||||||
| Cheng (24) | Early repolarization pattern (ERP) on ECG | ERP or not | Risk | 19 | 1,125/ 7,268 |
OR | 4.76 (3.62, 6.26) | 6.9 x 10−29 | No | 38.4% | No | NP | Yes | I | IV | I | Moderate |
| Aune (25) | Diabetes mellitus (DM) | DM or not | Risk | 14 | 3,510/ 280,737 |
RR | 2.02 (1.81, 2.25) | 4.54 x 10−37 | No | 0% | No | NP | Yes | I | I | I | Moderate |
| Aune (26) | Smoking | Current smoker or not | Risk | 4 | 1,061/ 203,386 |
RR | 2.08 (1.70, 2.53) | 4.85 x 10−13 | No | 17.5% | No | No | Yes | I | I | I | Moderate |
| Aune (27) | Physical activity | Physically active or not | Protective | 8 | 1,193/ 136,298 |
RR | 0.52 (0.45, 0.60) | 4.77 x 10−18 | No | 0% | No | NP | Yes | I | I | I | Critically low |
| Rattanawong (28) | Atrial fibrillation (AF) | AF or not | Risk | 28 | 3,258/ 75,465 |
RR | 2.04 (1.76, 2.35) | 2.83 x 10−22 | No | 43% | Yes | Yes | Yes | II | II | II | High |
| Pan (29) | Hypertension (HTN) | HTN or not | Risk | 9 | 1,211/ 837,795 |
RR | 2.1 (1.71, 2.58) | 1.89 x 10−12 | No | 56.7% | No | No | Yes | II | II | II | Moderate |
| Cheng (30) | Macrolides | Used or not | Risk | 11 | 58,810/ 6670,109 |
RR | 2.42 (1.60, 3.63) | 2.34 x 10−5 | Yes | 85.4% | No | No | Yes | III | NA | III | Moderate |
| Shi (31) | Depression | Depression or not | Risk | 4 | 2,399/ 83,659 |
HR | 1.98 (1.37, 2.88) | 3.1 x 10−4 | Yes | 59% | Yes | Yes | Yes | III | IV | III | Critically low |
| Chen (32) | Body mass index (BMI) | Overweight vs. normal BMI | Risk | 9 | 1,462/ 1188,730 |
RR | 1.21 (1.08, 1.35) | 0.001 | No | 7.7% | No | NP | Yes | III | III | III | Moderate |
| Heart failure or LV dysfunction population | |||||||||||||||||
| Barra (33) | Implanted Cardiac defibrillator (ICD) | Eligible or not for cardiac resynchronization therapy (CRT) | Intervention | 14 | 1,081/ 5,949 |
RR | 0.33 (0.24, 0.47) | 1.59 x 10−10 | No | 12.6% | No | NP | Yes | I | IV | I | Critically low |
| Coronary artery disease population | |||||||||||||||||
| Aune (25) | DM, in patients with coronary artery disease (CAD) | DM or not | Risk | 5 | 2,194/ 45,905 |
RR | 1.64 (1.36, 1.97) | 2.15 x 10−7 | Yes | 39.0% | Yes | No | Yes | II | II | II | Moderate |
| Rattanawong (28) | AF, in patients with CAD | AF or not | Risk | 4 | 1,352/ 19,542 |
RR | 1.56 (1.24, 1.96) | 1.7 x 10−4 | Yes | 34.7% | Yes | No | Yes | III | III | III | High |
| Hypertrophic cardiomyopathy population | |||||||||||||||||
| Rattanawong (28) | Atrial Fibrillation | Yes vs. No in patients with hypertrophic cardiomyopathy | Risk | 4 | 77/ 1,662 |
RR | 2.05 (1.22, 3.43) | 0.006 | Yes | 25.9% | No | Yes | Yes | IV | III | IV | High quality |
| Other populations | |||||||||||||||||
| Aune (25) | DM, in patients with AF, CAD, heart failure (HF), or hemodialysis | DM or not | Risk | 10 | 2,713/ 54,735 |
RR | 1.75 (1.51, 2.03) | 1.49 x 10−13 | No | 38.6% | Yes | Yes | Yes | II | II | II | Moderate |
CE, class of evidence; CES, class of evidence sensitivity analysis; CI, confidence interval; ES, effect size; ESB, excess significance bias; HR, hazard ratio; I2, heterogeneity; K, number of studies for each factor; LS, largest study with significant effect; MA, meta-analysis; n, number of cases; N, total number of cohorts per factor; NA, not assessable; NP, not pertinent, because the number of observed studies is less than the expected; NR, not reported; OR, odds ratio; PI, prediction interval; RR, risk ratio; SSE, small study effects.