Table 1.Characteristics of study population from the Healthy Twin Study
Subject characteristics |
All pairs (Sibling + twins)1
|
Monozygotic twins
|
Male |
Female |
Male |
Female |
No. of participants |
732 (38.85) |
1152 (61.15) |
332 (37.39) |
556 (62.61) |
Age (y) |
39.72 (8.21) |
39.04 (7.83) |
39.15 (7.50) |
37.78 (7.05) |
Education level |
|
|
|
|
Middle school or lower |
96 (13.11) |
155 (13.45) |
46 (13.86) |
53 (9.53) |
High school |
338 (46.17) |
583 (50.61) |
146 (43.98) |
290 (52.16) |
College or higher |
298 (40.71) |
414 (35.94) |
140 (42.17) |
213 (38.31) |
Equivalized household income |
|
|
|
|
≤252
|
177 (24.18) |
272 (23.61) |
55 (16.57) |
85 (15.29) |
25 - 753
|
434 (59.29) |
665 (57.73) |
210 (63.25) |
324 (58.27) |
>754
|
120 (16.39) |
215 (18.66) |
67 (20.18) |
147 (26.44) |
Occupation |
|
|
|
|
Manual |
278 (37.98) |
200 (17.36) |
118 (35.54) |
98 (17.63) |
Non-manual |
400 (54.64) |
414 (35.94) |
193 (58.13) |
218 (39.21) |
Others5
|
54 (7.38) |
538 (46.70) |
21 (6.33) |
240 (43.17) |
Smoking status |
|
|
|
|
Non-smoker |
172 (23.50) |
1025 (88.98) |
84 (25.38) |
498 (89.73) |
Ex-smoker |
179 (24.45) |
40 (3.47) |
86 (25.98) |
16 (2.88) |
Current smoker |
381 (52.05) |
83 (7.20) |
161 (48.64) |
41 (7.39) |
Smoking cessation attempted |
|
|
|
|
No |
103 (19.22) |
37 (31.90) |
34 (14.29) |
15 (27.78) |
Yes |
433 (80.78) |
79 (68.10) |
204 (85.71) |
39 (72.22) |
Successful smoking cessation |
|
|
|
|
No (not or less than 6 mo) |
374 (67.63) |
80 (66.67) |
159 (64.90) |
40 (71.43) |
Yes (more than 6 mo) |
179 (32.37) |
40 (33.33) |
86 (35.10) |
16 (28.57) |
Alcohol status |
|
|
|
|
Non-drinker |
82 (11.20) |
357 (30.99) |
52 (15.66) |
165 (29.73) |
Past-drinker |
34 (4.64) |
116 (10.07) |
13 (3.92) |
59 (81.94) |
Current-drinker |
616 (84.15) |
679 (58.94) |
267 (80.42) |
331 (59.64) |
Cigarettes/d6
|
16.95 (7.99) |
12.51 (38.04) |
16.17 (6.99) |
9.57 (6.05) |
Packs year6
|
16.42 (12.16) |
6.08 (6.33) |
14.89 (9.75) |
6.08 (5.18) |
FTND6
|
3.52 (2.39) |
2.29 (2.28) |
3.33 (2.18) |
2.59 (2.35) |
Table 2.Smoking indices and social determinants in sibling and monozygotic twin pairs (analyses between withinpair differences)
|
Difference (95% CI) per one grade increase in socio-economic status
|
|
Sibling + twin1 (n = 937 pairs)
|
Monozygotic twin (n = 442 pairs)
|
|
Smoking rate OR (95% CI) |
Smoking amount/d2 (β± 95% CI) |
Pack year3 (β± 95% CI) |
Smoking rate OR (95% CI) |
Smoking amount/d (β± 95% CI) |
Pack year (β± 95% CI) |
Education4
|
0.79 (0.62, 1.01) |
-0.87 (-2.69, 0.95) |
-2.05 (-4.74, 0.64) |
0.67* (0.51, 0.93) |
-1.13 (-2.52, -0.42) |
-2.90** (-4.77, -1.95) |
Income5
|
0.97 (0.77, 1.23) |
0.65 (-0.84, 2.14) |
-0.38 (-2.72, 1.97) |
1.30 (0.96, 1.75) |
-0.63 (-2.10, 0.12) |
-0.08 (-2.12, 0.96) |
Occupation6
|
0.97 (0.80, 1.19) |
-0.91 (-2.36, 0.54) |
0.74 (-1.44, 2.93) |
0.89 (0.69, 1.15) |
-2.48** (-3.52, -1.44) |
-8.70** (-10.29, -7.11) |
Table 3.Smoking cessation behaviors according to social determinants in sibling and monozygotic twin pairs (analyses by pair-wise differences)
|
Siblings + twins1 (n = 909 pairs)
|
Monozygotic twins (n = 436 pairs)
|
|
Attempted smoking cessation OR (95% CI) |
Successful smoking cessation (≥6 mo) OR (95% CI) |
FTND2 (β± 95% CI) |
Attempted smoking cessation OR (95% CI) |
Successful smoking cessation (≥6 mo) OR (95% CI) |
FTND (β± 95% CI) |
Education3
|
1.68 (0.79, 3.56) |
1.29 (0.68, 2.44) |
-0.70* (-1.28, -0.11) |
1.16 (0.42, 0.97) |
0.45* (0.21, 0.97) |
-0.18 (-0.25, 0.40) |
Income4
|
0.80 (0.44, 1.45) |
1.21 (0.70, 2.10) |
0.65* (0.15, 0.96) |
0.70 (0.25, 1.96) |
0.60 (0.28, 1.31) |
0.52* (0.09, 0.74) |
Occupation5
|
1.35 (0.73, 2.48) |
2.55** (1.50, 4.31) |
-0.28 (-0.77, 0.22) |
0.53 (0.15, 1.92) |
1.17 (0.35, 3.84) |
-1.29** (-1.80, -1.03) |
Table 4.Gender-specific smoking behavior patterns and social determinants in sibling pairs and twin pairs (analyses by within-pair differences in the two factors)
|
Siblings+twins1
|
Monozygotic twins
|
|
Smoking rate OR (95% CI) |
Smoking amount/d2 (β± 95% CI) |
Pack year3 (β± 95% CI) |
Smoking rate OR (95% CI) |
Smoking amount/d (β± 95% CI) |
Pack year (β± 95% CI) |
Male |
|
n=730 (365 pairs) |
|
|
n=331 (165 pairs) |
|
Education4
|
0.62** (0.45, 0.84) |
-1.21 (-3.91, 1.49) |
-2.00 (-6.78, 2.78) |
0.28** (0.18, 0.48) |
-1.03 (-2.54, 0.48) |
-2.99** (-4.81, -1.17) |
Income5
|
1.03 (0.77, 1.37) |
-1.35 (-4.56, 1.86) |
-6.55 (-12.35, 0.75) |
0.67 (0.37, 1.19) |
-0.28 (-1.93, 1.37) |
-0.85 (-2.87, 1.17) |
Occupation6
|
0.90 (0.69, 1.19) |
-2.47 (-4.72, 0.22) |
-2.66 (-7.19, 1.87) |
0.88 (0.43, 1.82) |
-2.63** (-4.43, -0.83) |
-6.75** (-8.96, -4.54) |
Female |
|
n=1144 (572 pairs) |
|
|
n=554 (277 pairs) |
|
Education |
0.95 (0.59, 1.53) |
-0.18 (-7.37, 7.23) |
1.81 (-6.03, 9.65) |
0.99 (0.63, 1.59) |
-1.51 (-5.86, 2.84) |
0.07 (-6.04, 6.19) |
Income |
1.01 (0.70, 1.47) |
-6.73 (-13.77, 0.31) |
5.05 (-2.75, 12.85) |
1.03 (0.70, 1.54) |
-3.11 (-6.50, 0.28) |
-3.19 (-6.91, 0.53) |
Occupation |
1.24 (0.90, 1.73) |
-0.08 (-5.14, 4.98) |
1.07 (-4.20, 6.34) |
1.11 (0.79, 1.56) |
-1.15 (-3.89, 1.59) |
2.79 (-1.40, 6.98) |
Table 5.Gender-specific smoking-cessation behavior and social determinants in sibling and twin pairs (using within-pair differences)
|
Siblings+twins1
|
Monozygotic twins
|
|
Attempted smoking cessation OR (95% CI) |
Successful smoking cessation (≥6 mo) OR (95% CI) |
FTND2 (β± 95% CI) |
Attempted smoking cessation OR (95% CI) |
Successful smoking cessation (≥6 mo) OR (95% CI) |
FTND (β± 95% CI) |
Male |
|
n=682 (341 pairs) |
|
|
n = 322 (161 pairs) |
|
Education3
|
1.07 (0.63, 1.81) |
1.51 (0.93, 2.46) |
-0.44 (-1.20, 0.32) |
1.10 (0.63, 1.94) |
0.77 (0.49, 1.22) |
-0.37 (-0.82, 0.08) |
Income4
|
0.85 (0.54, 1.35) |
0.85 (0.56, 1.30) |
0.04 (-0.52, 0.61) |
0.89 (0.52, 1.41) |
0.83 (0.55, 1.24) |
0.62 (-0.26, 1.50) |
Occupation5
|
1.00 (0.66, 1.53) |
1.62* (1.09, 2.42) |
-0.80 (-2.09, 0.49) |
1.18 (0.72, 1.94) |
1.13 (0.76, 1.67) |
-0.72* (-1.31, -0.13) |
Female |
|
n=1136 (568 pairs) |
|
|
n=550 (275 pairs) |
|
Education |
1.75 (0.40, 7.69) |
1.07 (0.25, 4.51) |
-0.64 (-3.07, 1.79) |
0.99 (0.30, 3.27) |
0.78 (0.49, 1.22) |
-0.13 (-1.11, 0.85) |
Income |
1.36 (0.41, 4.54) |
1.61 (0.35, 7.41) |
1.55 (-0.96, 4.06) |
0.98 (0.37, 2.59) |
0.83 (0.56, 1.24) |
-0.46 (-1.07, 0.15) |
Occupation |
0.67 (0.26, 1.69) |
0.57 (0.18, 1.80) |
1.15 (-0.67, 2.97) |
1.29 (0.55, 3.02) |
1.13 (0.77, 1.67) |
-0.44 (-1.09, 0.21) |