What is the treatment approach for chronic inducible urticaria?

Chronic Inducible Urticaria: Diagnosis and Treatment

Chronic inducible urticaria (CIndU) is a subtype of chronic urticaria characterized by the appearance of wheals and/or angioedema in response to specific physical or environmental triggers, requiring a stepwise treatment approach starting with high-dose second-generation H1 antihistamines and potentially escalating to omalizumab for refractory cases. 1, 2

Definition and Classification

• CIndU is defined by recurrent wheals, angioedema, or both that persist for more than 6 weeks and are reproducibly triggered by specific stimuli 1
• CIndU is divided into physical urticarias (triggered by physical stimuli) and non-physical urticarias (triggered by specific environmental factors) 1

Physical Urticarias:

• Dermographism (triggered by stroking or scratching the skin) 1
• Delayed pressure urticaria (appears after sustained pressure on the skin) 3
• Cold urticaria (triggered by cold exposure) 4
• Heat urticaria (triggered by heat exposure) 3
• Solar urticaria (triggered by sunlight) 3
• Vibratory angioedema (triggered by vibration) 3

Non-Physical Urticarias:

• Cholinergic urticaria (triggered by increased core body temperature, often during exercise or emotional stress) 4
• Contact urticaria (triggered by skin contact with allergens or chemicals) 3
• Aquagenic urticaria (triggered by water contact) 1

Diagnostic Approach

• Diagnosis requires a detailed history focusing on the specific triggers that induce symptoms 1
• Provocation testing is essential to confirm the diagnosis and identify the specific trigger 3
• For physical urticarias, standardized challenge tests should be performed to reproduce symptoms under controlled conditions 2
• The Urticaria Control Test (UCT) is recommended to assess disease control in all forms of chronic urticaria, including CIndU 3
• Individual weals in CIndU typically last less than 24 hours, distinguishing it from urticarial vasculitis where lesions persist beyond 24 hours 5

Treatment Algorithm

First-Line Treatment:

• Second-generation H1-antihistamines at standard doses are recommended as initial therapy 6
• If inadequate response after 2-4 weeks, increase dose up to 4 times the standard dose 6

Second-Line Treatment:

• For patients with inadequate response to high-dose antihistamines, consider adding:
  • H2-antihistamines 6
  • Leukotriene receptor antagonists 6
  • Brief courses of systemic corticosteroids for severe flares (not for long-term use) 5

Third-Line Treatment:

• Omalizumab (300mg every 4 weeks) is FDA-approved for chronic spontaneous urticaria and can be used off-label for treatment-resistant CIndU 7
• Response to omalizumab varies among CIndU subtypes - cold urticaria often responds well, while symptomatic dermographism may be more resistant 8

Fourth-Line Treatment:

• For refractory cases, consider cyclosporine (up to 5mg/kg body weight) with appropriate monitoring of blood pressure and renal function 5
• Immunomodulatory agents may be necessary for severe, treatment-resistant cases 1

Management Strategies

• Trigger avoidance is the cornerstone of management when specific triggers can be identified 1
• Physical desensitization may be helpful in some forms of CIndU, particularly cold urticaria 1
• Regular assessment of disease activity and impact on quality of life should guide treatment decisions 3
• The UCT should be used to monitor treatment response, with a score ≥12 indicating well-controlled disease 3

Important Considerations

• CIndU is often more resistant to standard antihistamine doses compared to chronic spontaneous urticaria 8
• Some forms of CIndU (particularly cold urticaria) can potentially progress to anaphylaxis in severe cases 3
• The FDA label for omalizumab specifically notes it is not indicated for treatment of other forms of urticaria beyond chronic spontaneous urticaria, making its use in CIndU off-label 7
• Treatment should be continued until complete symptom control is achieved and maintained for at least 3-6 months before considering dose reduction 5

Special Populations

• In adolescents (12 years and older), the treatment approach is similar to adults 7
• For pregnant women, second-generation antihistamines (particularly loratadine and cetirizine) are preferred due to their established safety profile 5