Table 1. Characteristics of the study populations.
| Clinical Characteristic | NFBC86 | NFBC66 | YFS | FINRISK 1997 |
| Number of participants (women/men) | 3,976 (1,997/1,979) | 4,671 (2,321/2,350) | 2,171 (1,155/1,016) | 1,846 (995/851) |
| Age (y) | 16 (—) | 31 (—) | 31.9 (4.9) | 32.3 (4.5) |
| BMI (kg/m2) | 21.2 (3.4) | 24.6 (4.0) | 25.0 (4.4) | 24.7 (4.0) |
| Systolic blood pressure (mm Hg) | 116 (13) | 125 (13) | 117 (13) | 125 (14) |
| Total cholesterol (mmol/l) | 4.2 (0.9) | 5.3 (1.2) | 5.0 (1.0) | 5.0 (1.0) |
| HDL cholesterol (mmol/l) | 1.5 (0.3) | 1.7 (0.4) | 1.6 (0.4) | 1.6 (0.3) |
| Triglycerides (mmol/l) | 0.9 [0.7–1.1] | 1.0 [0.7–1.4] | 1.1 [0.9–1.6] | 0.9 [0.7–1.3] |
| Plasma glucose (mmol/l) | 5.0 [4.7–5.2] | 5.0 [4.7–5.3] | 5.0 [4.7–5.3] | 4.8 [4.5–5.1] |
| Insulin (IU/l) | 9.5 [7.3–12] | 7.5 [6.2–9.4] | 6 [5]–[9] | 4.7 [3.3–6.6] |
| Physical activity index (h/wk) | 30 [18]–[43] | 11 [4]–[20] | 13 [3]–[31] | — |
| Alcohol usage (g/d) | — | 4 [1]–[11] | 5 [0–15] | 4 [0–11] |
| Smoking prevalence (percent) | 12% (11–13) | 40% (39–42) | 24% (22–26) | 28% (26–30) |
| Prevalence of overweight (percent) | 9% (8–10) | 31% (30–32) | 32% (30–33) | 32% (30–34) |
| Prevalence of obesity (percent) | 3% (2–3) | 8% (7–9) | 12% (11–13) | 9% (8–10) |
| Association of gene score for elevated BMI with observed BMI (β ± standard error, kg/m2) | 0.91±0.10 | 1.21±0.11 | 0.92±0.17 | 1.14±0.17 |
| p = 8×10−21 | p = 1×10−28 | p = 7×10−8 | p = 6×10−11 | |
| F-statistic = 88 | F-statistic = 125 | F-statistic = 29 | F-statistic = 39 | |
| Variation in observed BMI explained by the gene score for elevated BMI | 2.2% | 2.6% | 1.3% | 2.1% |
Values are mean (SD), median [interquartile range], or percentage (95% confidence interval) for normally distributed, skewed, and categorical variables, respectively. The gene score for predisposition to elevated BMI was derived based on weighting each genetic variant in the score by effects established previously in genome-wide meta-analysis [34].