Urticaria Diagnosis

• Diagnosis is based on patient’s history and physical examination

Chronic Spontaneous Urticaria

• Goals of diagnostic work-up include confirming the diagnosis and ruling out differential diagnoses, identifying underlying causes, conditions that affect disease activity (eg food, drugs [NSAIDs], stress, infections), comorbidities, and consequences of chronic spontaneous urticaria (anxiety, depression, sexual dysfunction, sleep disturbances), assessing predictors of disease course and treatment response, and monitoring disease activity (UAS, UAS7, AAS), impact (CU-Q2oL, AE-QoL) and control (UCT, AECT)
• Further tests are requested if indicated by the patient’s history, physical examination and basic tests, most notably in patients with chronic and/or on-and-off disease presentation

Chronic Inducible Urticaria

• Goals of diagnostic work-up include ruling out differential diagnoses, identifying subtype, and determining trigger thresholds

• Classified as acute or chronic, and as spontaneous (no definite triggering factor) or inducible (a specific definite triggering factor is identified)
  • A specific cause is more likely to be identified in acute cases
• Can be triggered by immunological or non-immunological mechanism

Acute Urticaria

• Lesions occurring ≤6 weeks in duration and usually without angioedema
• More common in children and young adults and tends to have a triggering event

Chronic Urticaria

• More common in adults (3rd and 4th decades of life), symptoms last >6 weeks
• A patient can have >1 form of chronic urticaria including >1 form of chronic inducible urticaria

Chronic Spontaneous Urticaria

• Presence of wheals, angioedema or both for >6 weeks due to factors that are not identifiable or idiopathic
• Known causes include autoimmunity type I (autoallergic) with IgE autoantibodies to self-antigens and autoimmunity type IIb with mast cell-directed activating autoantibodies 
• May recur after achieving months or years of full remission

Chronic Inducible Urticaria

• Cold urticaria
• Delayed pressure urticaria
• Heat urticaria
• Symptomatic dermographism
  • Daily lesions and recurrent episodic lesions are not differentiated
• Solar urticaria
• Vibratory angioedema
• Aquagenic urticaria
• Cholinergic urticaria
• Contact urticaria

Autoimmune Chronic Spontaneous Urticaria (ACU)

• Proposed gold standard for diagnosis of ACU (combination of all 3 parameters):
  • Positive bioassay (eg basophil histamine release assay [BHRA], basophil activation marker expression) and
  • Positive autoreactivity (eg positive autologous serum skin test [ASST]) and
  • Positive immunoassay for specific IgG autoantibodies against FcεRIα and/or anti-IgE

Chronic Urticaria

• Assess disease activity of chronic urticaria
  • Several guidelines recommend using the Urticaria Activity Score (UAS) system in assessing disease severity and treatment effectivity in patients with wheals

   

  URTICARIA ACTIVITY SCORE (UAS)
  Score	Wheals	Pruritus
  0	None	None
  1	Mild (<20 wheals/24 hours)	Mild (present but not annoying or troublesome)
  2	Moderate (20–50 wheals/24 hours)	Moderate (troublesome but does not interfere with normal daily activity or sleep)
  3	Intense (>50 wheals/24 hours or large confluent areas of wheals)	Intense (severe pruritus sufficiently troublesome to interfere with normal daily activity or sleep)
  Reference: The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Allergy. 2022 Mar;77(3):734-766.

   

  • Summation of scores of symptoms during a 7-day period (UAS7)
    • 0 = no wheals, no pruritus
    • 1 = mild wheals (<20 wheals within 24 hours) + mild pruritus (nontroublesome) 
    • 2 = moderate wheals (20-50 wheals within 24 hours) + moderate pruritus (troublesome but does not interfere with daily activities or sleep) 
    • 3 = intense wheals (>50 wheals within 24 hours or large confluent wheals) + intense pruritus (severely troublesome, interferes with daily activities and sleep)
  • The Chronic Urticaria Quality of Life questionnaire (CU-Q2oL) is the recommended quality of life tool to assess the quality of life impairment specific to chronic spontaneous urticaria 
  • The Angioedema-specific Quality of Life tool (AE-QoL), Urticaria Control Test (UCT), Angioedema Control Test (AECT) and Angioedema Activity Score (AAS) may also be used to assess patient's quality of life and disease status, which may help in treatment decisions

Chronic Inducible Urticaria

• Provocation threshold measurements are used to assess disease activity and control, while the UCT is used to determine how well the disease is prevented from recurring

• Look for typical lesions of urticaria
  • Wheals which typically are fleeting, lasting within 30 minutes-24 hours, have a central swelling of variable size surrounded by erythema and associated with itching, sometimes burning sensation
  • Angioedema characterized by a sudden evident swelling of the lower dermis and subcutis or mucous membranes, that is sometimes painful which may last up to 72 hours
  • Lesions may appear on any part of the body

Dermographism/Dermatographism

• Stroke the arm to test for dermographism/dermatographism
• Discontinue antihistamine therapy for at least 2-3 days and immunosuppressive therapy for at least a week before testing

Acute Urticaria 

• Routine laboratory work-ups are not required except when the cause of the urticaria points to a type I food hypersensitivity or other triggering factors like medications (eg nonsteroidal anti-inflammatory drugs [NSAIDs])