Table 2. Descriptive characteristics of the 11 studies contributing to the genome-wide meta-analysis.
| Study | n | Sex (% male) | Age (years) |
Cotinine (ng/ml)a |
Medium | Method | ||
|---|---|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | |||||
| ALSPAC | 258 | 50.4 | 17.8 | 0.4 | 182.1 | 107.2 | Plasma | Immunoassay |
| CARDIA | 387 | 47.8 | 25.3 | 3.4 | 202.0 | 137.8 | Plasma | Radioimmunoassay |
| FinnTwin | 145 | 46.2 | 23.0 | 1.5 | 206.6 | 107.5 | Serum | Mass spectrometry |
| FINRISK | 218 | 59.8 | 48.4 | 11.6 | 223.6 | 167.7 | Serum | Mass spectrometry |
| Framingham | 93 | 43.0 | N/A | N/A | 101.3 | 55.6 | Plasma/serum | Mass spectrometry |
| GenMets | 485 | 57.8 | 47.3 | 11.2 | 490.1 | 250.6 | Serum | Immunoassay |
| MESA | 189 | 57.5 | 59.6 | 8.9 | 4818.2 | 4105.5 | Urine | Immunoassay |
| NESDA | 808 | 36.5 | 41.5 | 12.4 | 260.9 | 224.4 | Plasma | Immunoassay |
| NTR | 897 | 44.1 | 43.6 | 13.9 | 278.5 | 269.7 | Plasma | Immunoassay |
| TwinsUK | 676 | 8.9 | 48.1 | 13.7 | 175.3 | 63.6 | Plasma | Mass spectrometry |
| YFS | 392 | 55.4 | 33.8 | 6.2 | 200.6 | 108.9 | Serum | Mass spectrometry |
aCotinine mean and standard deviation values refer to raw values prior to standardisation (i.e., conversion to Z-scores). Further study details available in Text S1. SD: standard deviation.