Table 1.
Characteristics of empirical studies on social determinants of DNA methylation
| k | % | ||
|---|---|---|---|
| Initial Study DesignA | Case-control | 5 | 7% |
| Cohort | 60 | 90% | |
| Mixed design in multi-national study | 2 | 3% | |
| Original survey design - longitudinal | 43 | 64% | |
| Epigenetic subsample examined longitudinally | 2 | 5% | |
| Initial Sampling FrameA | Convenience | 27 | 40% |
| Probability-based | 37 | 55% | |
| Representativeness maintained in epigenetic subsample | 14 | 38% | |
| Mixed sampling frames in multi-national studies | 3 | 4% | |
| Region of Study | North America | 41 | 61% |
| United Kingdom | 9 | 13% | |
| Other Western European nations | 6 | 9% | |
| Asia | 4 | 6% | |
| Central and South America | 2 | 3% | |
| Middle East | 1 | 1% | |
| Africa | 1 | 1% | |
| Multi-national | 3 | 4% | |
| Sample Size | <100 | 15 | 22% |
| 100–300 | 20 | 30% | |
| 301–600 | 13 | 19% | |
| 601–1000 | 7 | 10% | |
| >1000 | 12 | 18% | |
| Ages includedB | 18 – 34 years | 26 | 39% |
| 35 – 60 years | 45 | 67% | |
| 61+ years | 15 | 22% | |
| Sex Composition | Female only | 13 | 19% |
| Both Sexes | 48 | 72% | |
| Racial/Ethnic Composition | North American Samples (k=41): | ||
| White only | 3 | 7% | |
| Black only | 12 | 29% | |
| Latinx only | 1 | 2% | |
| Diverse | 21 | 51% | |
| Unspecified | 4 | 10% | |
| European Samples (k=15): | |||
| White only | 4 | 20% | |
| Unspecified | 11 | 67% | |
| Other regions and multinational samples (k= 11): | |||
| Mono-ethnic | 2 | 18% | |
| Diversity across multinational sample | 2 | 18% | |
| Unspecified | 7 | 64% |
A.
Initial design and sampling frame refers to the larger study from which the epigenetic sample was drawn. See sub-bullets for specifics on epigenetic subsamples drawn from larger cohort designs.
B.
Categories are not mutually exclusive, and therefore will not sum to 100%.