Table 2.
Concordance and tetrachoric correlations
| Zygosity | Concordant pairs with THA due to OA n (%) | Discordant pairs with THA due to OA n (%) | Concordant pairs without THA n (%) | Total twin pairs in zygosity groups n (%) | Tertrachoric correlations (rho) |
|---|---|---|---|---|---|
| MZM | 10 (0.2) | 57 (1.2) | 4558 (98.6) | 4625 (100) | 0.70 |
| DZM | 5 (0.1) | 148 (1.8) | 8107 (98.1) | 8260 (100) | 0.33 |
| MZF | 9 (0.2) | 72 (1.5) | 4773 (98.3) | 4855 (100) | 0.66 |
| DZF | 5 (0.1) | 148 (1.9) | 7740 (98.0) | 7893 (100) | 0.33 |
| OSDZ | 7 (0.05) | 223 (1.25) | 17,602 (98.7) | 17,832 (100) | 0.41 |
DZF dizygotic females, DZM dizygotic males, MZF monozygotic females, MZM monozygotic males, OA Osteoarthritis, OSDZ opposite-sex dizygotic twin pairs, THA Total hip arthroplasty