Table 1. Probandwise Concordance Rates and Tetrachoric Correlations.
| Twin pair | Concordant HS negative | Discordant | Concordant HS positive | Prevalence of HS, % | Probandwise concordance | Tetrachoric correlation (95% CI) |
|---|---|---|---|---|---|---|
| MZ pairs | 1295 | 22 | 5 | 1.2 | 0.31 | 0.76 (0.74-0.78) |
| Female pairs | 954 | 19 | 5 | 1.5 | 0.34 | 0.77 (0.74-0.79) |
| Male pairs | 341 | 3 | 0 | 0.4 | NA | 0.67 (0.61-0.72)a |
| DZ pairs | 996 | 24 | 1 | 1.3 | 0.08 | 0.36 (0.31-0.41) |
| Female pairs | 410 | 16 | 0 | 1.9 | NA | 0.24 (0.15-0.33)a |
| Male pairs | 165 | 2 | 0 | 0.6 | NA | 0.66 (0.56-0.74)a |
| Opposite-sex pairs | 421 | 6 | 1 | 1.9 | 0.25 | 0.70 (0.65-0.75) |
Abbreviations: DZ, dizygotic; HS, hidradenitis suppurativa; MZ, monozygotic; NA, not applicable.
a
To correct for continuity, cells with a count of 0 were replaced with 1/30th of the discordant cell count to calculate tetrachoric correlations.