Table 1 Factors associated with longer duration or more difficult to treat chronic urticaria

Failure of a single labeled dose of an H₁receptor blocker to control chronic urticaria

Explore quality of life

Long duration (6 months or more) at time of presentation

Angioedema

Up to 40% of patients

Physical Urticaria

Inquire about and test where indicated

Autoimmunity diseases/test results*

Positive autologous serum or plasma intradermal skin test (some studies)

Use upmost caution with sera and plasma

Serum IgG anti-IgE or IgG anti-FcϵRI

Hypertension

Subclinical activation of the extrinsic coagulation pathway (Prothrombin fragments detected) or evidence of fibrinolysis (D-Dimer > 500 ng/mL)

Basophil activation (CD203c+)