Non-invasive Diagnosis of Cold Urticaria

Study Overview
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Brief Summary
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The investigators subjected 63 patients (39 with typical Cold urticaria and 24 with atypical Cold urticaria ) and 15 healthy controls to TempTest® cold stimulation tests and critical temperature threshold assessments. Blood microcirculation photoplethysmography measurements were performed 5 min before and 10 min after the ice cube on the volar forearm.

Official Title
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Photoplethysmography for Non-invasive Diagnosis of Cold Urticaria

Conditions
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Urticaria Cold

Intervention / Treatment
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* Device: Cold stimulation tests / critical temperature threshold


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Cold urticaria Exclusion Criteria: -

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Typical ColdU<br>39 patients had typical ColdU confirmed by positive ICT and TempTest® CSTs. | Device: Cold stimulation tests / critical temperature threshold<br>* ICT was performed following a standard protocol. Briefly, a melting ice cube in thin plastic bag was placed on the volar surface of the patient forearm for 5 min, with macroscopic assessment of the test site 10 min later. TempTest® CSTs were done with TempTest® 4.0 (Courage & Khazaka, Cologne, Germany), which has a single Peltier element (length: 350 mm, width: 2 mm) that provides a continuous temperature gradient from 4°C to 44°C. The use of TempTest® allows for reproducible and standardized cold (and heat) provocation tests and the identification of CTTs. TempTest® CST results were also assessed 10 min after the end of cold exposure.<br>|
| Experimental: Atypical ColdU<br>24 patients had atypical ColdU with negative ICT and TempTest® CSTs. | Device: Cold stimulation tests / critical temperature threshold<br>* ICT was performed following a standard protocol. Briefly, a melting ice cube in thin plastic bag was placed on the volar surface of the patient forearm for 5 min, with macroscopic assessment of the test site 10 min later. TempTest® CSTs were done with TempTest® 4.0 (Courage & Khazaka, Cologne, Germany), which has a single Peltier element (length: 350 mm, width: 2 mm) that provides a continuous temperature gradient from 4°C to 44°C. The use of TempTest® allows for reproducible and standardized cold (and heat) provocation tests and the identification of CTTs. TempTest® CST results were also assessed 10 min after the end of cold exposure.<br>|
| Other: Control group<br>15 healthy controls (HCs) who had no history of pathological reactions associated with cold exposure, and all of them had negative CSTs | Device: Cold stimulation tests / critical temperature threshold<br>* ICT was performed following a standard protocol. Briefly, a melting ice cube in thin plastic bag was placed on the volar surface of the patient forearm for 5 min, with macroscopic assessment of the test site 10 min later. TempTest® CSTs were done with TempTest® 4.0 (Courage & Khazaka, Cologne, Germany), which has a single Peltier element (length: 350 mm, width: 2 mm) that provides a continuous temperature gradient from 4°C to 44°C. The use of TempTest® allows for reproducible and standardized cold (and heat) provocation tests and the identification of CTTs. TempTest® CST results were also assessed 10 min after the end of cold exposure.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Photoplethysmography amplitude | To compute the blood flow signal, we subtracted slowly time-varying background and frequency components out of the cardiovascular-related range of 0.3-7 Hz. The resulting well-matched, noise-free and intensity-corrected blood flow images are suited for PPG calculation by averaging the intensity pixel values of each frame. The PPG amplitude is proportional to the amount of arterial blood that reaches the visualized skin area and thus characterizes its blood perfusion. It is measured in arbitrary units (AU). We performed photoplethysmographic assessments of the volar forearm of all patients 5 minutes before and 10 minutes after the beginning and end of ice cube application. | 10 min after the end of cold exposure |