Standard cold test misses 1 in 3 cold urticaria patients, study finds

The go-to diagnostic test for cold urticaria (ColdU) — the standard cold stimulation test (SCST) — is leaving a significant number of patients undiagnosed. A new multinational observational study found that roughly 1 in 3 patients with convincing cold-induced symptoms tested negative on the SCST, revealing a clinically distinct subgroup that has long been poorly understood.

The study analyzed 364 ColdU patients across 11 urticaria centers in nine countries. SCST-negative patients tended to be younger, had earlier disease onset, were more likely to have a family history of ColdU, and responded better to standard-dose antihistamines. Meanwhile, SCST-positive patients carried a heavier clinical burden — with higher rates of angioedema, breathing difficulties, and cardiovascular symptoms — and were more frequently prescribed adrenaline autoinjectors.

Key Takeaways:

• A negative SCST should not rule out ColdU — clinicians should review triggers, symptomatic sites, and consider modified provocation testing
• SCST-negative patients were 2.47x more likely to have a family history of ColdU and 2.23x more likely to have concomitant chronic spontaneous urticaria
• SCST-positive patients had nearly 3x the rate of breathing difficulties compared to SCST-negative patients (28.4% vs 10.7%)

Why it matters: Misdiagnosis or delayed diagnosis of ColdU can leave patients vulnerable to potentially life-threatening reactions. This study highlights a critical gap in current diagnostic practice and calls for a more comprehensive, symptom-driven approach beyond a single negative test result.