From: Genetic and environmental influence on lung function impairment in Swedish twins
Group | 1 | 2 | 3 | 4 | 5 | 6 | Total |
---|---|---|---|---|---|---|---|
Symptoms: twin1, twin2 | ++ | -- | -- | -- | -+ | -+ | |
Smoking > 10 PY: twin1, twin2 | -- | -+ | ++ | -- | ++ | ||
No of available | 834 | 12,008 | 7,708 | 4,158 | 1,050 | 758 | 26,516 |
No of invited | 394 | 128 | 164 | 106 | 86 | 152 | 1,030 |
No of participating | 130 | 56 | 79 | 43 | 42 | 42 | 392 |
Participation in % of available | 15.6 | 0.5 | 1.0 | 1.0 | 4.0 | 5.5 | 1.5 |