Table 3: Predictors of urticaria in the co-twin of an affected twin, in twin pairs, 20–51 years of age.

Crude HR P value Adjusted HR P value   (95% CI) (95% CI) Zygosity          DZ 1.00   1.00    MZ 1.57 (0.71–3.47) 0.267 1.42 (0.63–3.18) 0.394 Sex          Males 1.00   1.00    Females 1.86 (0.78–4.44) 0.160 1.86 (0.78–4.45) 0.165 Age at onset 0.98 (0.93–1.03) 0.328 0.98 (0.93–1.03) 0.346

DZ: dizygotic twins; MZ: monozygotic twins. HR: hazard ratio; CI: confidence interval. Adjusted HR is multivariably adjusted.