highly significantp = 2.9 × 10 −20
Highly significant differences were observed between the means of three variables—the Toronto sample had more PsA patients (93.0% vs. 58.3%, p = 2.9 × 10 −20 ), while the Michigan sample had a higher mean age (51.4 yrs vs. 46.0 yrs, p = 8.6 × 10 −7 ) and a higher percentage of patients with a family history of psoriasis (60.6% vs. 42.9 %, p = 4.5 × 10 −5 ).