Critical temperature threshold measurement for cold urticaria: a randomized controlled trial of H(1) -antihistamine dose escalation

BACKGROUND

Cold urticaria is a rare but severe and potentially lethal condition. It is primarily treated symptomatically with H(1) -antihistamines. However, patients have a variable response to these drugs and, to date, it has not been possible to predict readily the response to therapy of individual patients.

OBJECTIVES

To assess the severity of the cold urticaria in naive patients and the response to therapy of patients treated with increasing doses of an H(1) -antihistamine by measurement of critical temperature thresholds (CTT) for producing weals on the forearm.

METHODS

This was a two-centre, hospital-based, double-blind, randomized, parallel-group study of patients with a confirmed diagnosis of cold urticaria of at least 6 months' duration. Patient groups received either a constant dose of desloratadine 5 mg daily for 6 weeks (n = 13), or escalating doses of desloratadine: 5 mg daily for the first 2 weeks, 10 mg daily for the second 2 weeks and 20 mg daily for the final 2 weeks (n = 15). Only one adverse event that appeared to be drug related was reported: mild fatigue after treatment with desloratadine 10 mg that lasted for about 3 weeks and resolved at the end of the study.

RESULTS

The desloratadine 5 mg daily dose produced a submaximal reduction of mean CTT which remained relatively constant over 6 weeks. Dose escalation increased efficacy, the reduction in mean CTT at four-times the standard daily dose being significantly greater (P = 0·03) than with the standard dose. Individually, no patient became symptom free (CTT < 4 °C) on 5 mg, while two became symptom free on 10 mg and a further three on 20 mg desloratadine daily.

CONCLUSIONS

Measurement of CTT allows for individualized risk management and therapy in patients with cold urticaria.

Effects of a pseudoallergen-free diet on chronic spontaneous urticaria: a prospective trial

BACKGROUND

Chronic spontaneous urticaria is a skin disorder that is difficult to manage and can last for years. 'Pseudoallergens' are substances that induce hypersensitive/intolerance reactions that are similar to true allergic reactions. They include food additives, vasoactive substances such as histamine, and some natural substances in fruits, vegetables and spices. Eliminating pseudoallergens from the diet can reduce symptom severity and improve patient quality of life.

AIM

To assess the effects of a pseudoallergen-free diet on disease activity and quality of life in patient's chronic spontaneous urticaria.

METHODS

Study subjects had moderate or severe chronic spontaneous urticaria that had not responded adequately to treatment in primary care. For 3 weeks, subjects followed a pseudoallergen-free diet. They kept a clinical diary, which recorded their wheal and pruritus severity each day, to yield a clinical rating of chronic spontaneous urticaria severity (the UAS4 score). The subjects also completed the DLQI, a validated quality-of-life instrument. Use of antihistamines and glucocorticoids was minimized, recorded, and analysed. Subjects were classified into nine response categories, according to the changes in symptom severity (UAS4), quality of life (DLQI) and medication usage.

RESULTS

From the 140 subjects, there were 20 (14%) strong responders and 19 (14%) partial responders. Additionally, there were nine (6%) subjects who made a substantial reduction in their medication without experiencing worse symptoms or quality of life.

CONCLUSIONS

Altogether the pseudoallergen-free diet is beneficial for one in three patients. The pseudoallergen-free diet is a safe, healthy and cost-free measure to identify patients with chronic spontaneous urticaria that will benefit from avoiding pseudoallergens.