Table 2: Predictors of urticaria in a sample of 575 Danish twins, 20–51 years of age.

Urticaria difference (%)Crude HR (95% CI)P valueAdjusted HR (95% CI)P value

Sex14.31.96 (1.39–2.80)0.0002.09 (1.46–2.99)0.000
BMI0.20.98 (0.94–1.02)0.249ns
Zygosity1.71.01 (0.72–1.42)0.963ns
Smoking ever4.10.81 (0.58–1.11)0.192ns
Asthma9.71.60 (1.14–2.25)0.007ns
Hay fever13.91.93 (1.38–2.71)0.0001.92 (1.36–2.72)0.000
Atopic dermatitis10.61.63 (1.15–2.30)0.0061.44 (1.02–2.06)0.041
Positive skin prick test7.41.45 (1.04–2.01)0.028ns
Serum total IgE19.21.31 (1.03–1.68)0.031ns

Urticaria difference is the absolute difference in prevalence between exposure groups; for example for sex the difference in the prevalence of urticaria between males and females is 14.3%. All numbers are (%) except BMI (difference in mean BMI between urticaria patients and non-urticaria patients) and serum total IgE (difference in mean serum total IgE (log-transformed) between urticaria patients and non-urticaria patients).
HR: hazard ratio; CI: confidence interval; BMI: body mass index. Adjusted HR is multivariably adjusted.