Table.
Pairwise distribution of twins with osteoporotic fracture in Finnish twin cohort*
| Detail | Total No of pairs | Fracture cases | Overall cumulative fracture risk† (95% CI) | Discordant pairs (D) | Concordant pairs (C) | Pairwise concordance‡ (95% CI) | Probandwise concordance§ (95% CI) | Relative fracture risk¶ (95% CI) |
|---|---|---|---|---|---|---|---|---|
| All pairs | ||||||||
| Male MZ | 1087 | 89 | 0.041 (0.033 to 0.050) | 73 | 8 | 0.099 (0.044 to 0.185) | 0.180 (0.072 to 0.29) | 4.39 (2.70 to 7.16) |
| Male DZ | 2623 | 181 | 0.035 (0.030 to 0.039) | 173 | 4 | 0.023 (0.006 to 0.057) | 0.044 (0.002 to 0.086) | 1.28 (0.64 to 2.56) |
| Female MZ | 1221 | 161 | 0.066 (0.057 to 0.077) | 133 | 14 | 0.095 (0.053 to 0.155) | 0.174 (0.095 to 0.25) | 2.64 (1.83 to 3.81) |
| Female DZ | 2618 | 355 | 0.068 (0.061 to 0.075) | 303 | 26 | 0.079 (0.052 to 0.114) | 0.146 (0.096 to 0.20) | 2.16 (1.65 to 2.83) |
| Birth year 1919 or earlier | ||||||||
| Male MZ | 218 | 44 | 0.101 (0.073 to 0.129 | 30 | 7 | 0.189 (0.080 to 0.352) | 0.318 (0.14 to 0.50) | 3.15 (1.88 to 5.28) |
| Male DZ | 389 | 53 | 0.068 (0.052 to 0.088) | 45 | 4 | 0.082 (0.023 to 0.196) | 0.151 (0.02 to 0.28) | 2.22 (1.11 to 4.41) |
| Female MZ | 323 | 90 | 0.139 (0.113 to 0.166) | 74 | 8 | 0.098 (0.043 to 0.183) | 0.178 (0.07 to 0.28) | 1.28 (0.78 to 2.07) |
| Female DZ | 655 | 194 | 0.148 (0.129 to 0.167) | 158 | 18 | 0.102 (0.058 to 0.147) | 0.186 (0.11 to 0.26) | 1.25 (0.91 to 1.73) |
| Birth year 1920–45 | ||||||||
| Male MZ | 869 | 45 | 0.026 (0.019 to 0.035) | 43 | 1 | 0.023 (0.001 to 0.120) | 0.044 (−0.04 to 0.13) | 1.72 (0.43 to 6.86) |
| Male DZ | 2234 | 128 | 0.029 (0.024 to 0.034) | 128 | 0 | 0.000 (0.000 to 0.028) | 0.000 | 0.00 |
| Female MZ | 898 | 71 | 0.040 (0.031 to 0.050) | 59 | 6 | 0.092 (0.035 to 0.190) | 0.169 (0.051 to 0.29) | 4.28 (2.43 to 7.51) |
| Female DZ | 1963 | 161 | 0.041 (0.035 to 0.048) | 145 | 8 | 0.052 (0.023 to 0.100) | 0.099 (0.036 to 0.16) | 2.42 (1.49 to 3.95) |
All subjects with osteoporotic fracture, as identified from Finnish hospital discharge register in 1972–96, were included. †Overall cumulative fracture risk is calculated by dividing number of fracture cases by total number of individuals—for example, on first row of table 89/2×1087=0.041. ‡Pairwise concordance is calculated by formula of C/C+D—for example, on first row of the table 8/81=0.099. §Probandwise concordance is calculated by formula of 2C/(2C+D)—for example, on first row of table 2×8/(2×8+73)=0.180. ¶Relative fracture risk is calculated by dividing probandwise concordance by overall cumulative fracture risk—for example, on first row of table 0.180/0.041=4.39. MZ=monozygotic; DZ=dizygotic.