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Do oral anti-histamines stop the itch of atopic dermatitis?

Three Part Question

In [children with atopic eczema] does the [use of oral antihistamines] [reduce the incidence of itching]?

Clinical Scenario

You are a paediatric SHO, on a night shift. You are called to the ward to see a 6 year old girl, who cannot get to sleep because her eczema is too itchy. The nurses want you to prescribe an anti-histamine, but you doubt the efficacy of this treatment. As it is a surprisingly quiet shift, you go off to do a literature search.

Search Strategy

Cochrane, PubMed, SUMSearch
PubMed: Search words "atopic dermatitis" AND "chlorpheniramine" OR "antihistamines".
Limits English, human, child < 18 years

Search Outcome

Cochrane: None
PubMed: 14 papers of which 2 were relevant.
SUMSearch: 1 paper already retrieved by Pubmed

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Munday J et al,
2002,
155 paediatric patients with atopic dermatitis causing nocturnal itching and scratching, randomised to placebo or chlorpheniramine. Age 1-12 years.RCT, Double blind, Multi-centre (1b)Cessation of nocturnal itching and scratching compared to any itching symptoms at all. Assessed over 4 week period with itching scores and diary cards1-5 years: Small reduction in symptoms in children age 1-5 years, but not statistically significant. ARR 18%, (95% CI 0.05, 0.41)

6-12 years: No difference in 6-12 years. ARR -12%, (95%CI 0.35, 0.11)
Unclear how patients randomised and concealment of group 4 patients not accounted for in final data analysis Patients from different centres had differing intensity of treatment prior to study Unvalidated 5 point rating scale
La Rosa M, et al,
1994,
22 children with atopic dermatitis, randomised to placebo or cetirizine Age 6-12 yearsRCT, Double blind (1b)Decrease in pruritis. Assessed over 4 and 8 week period with scoring system and clinical assessmentCitirizine reduced symptoms more than placebo over first week, but no percentage reduction given (P<0.02)
Pruritis scores the same at 4 weeks intervals
No data on randomisation details and concealment Small numbers Not specified who performed clinical assessments Results not specified, no confidence intervals, arbitrary scales on graphs for intensity of pruritis Percentage improvement figures were not given for both placebo and treatment groups, so not comparable

Comment(s)

Current teaching in the treatment of atopic dermatitis incorporates the use of oral anti-histamines to eliminate itch. These are thought to work on the H1 receptor to decrease histamine release and therefore eliminate itch. In addition the older anti-histamines have a sedative effect, encouraging a complete night's sleep. The study by La Rosa et al was a small study, with only 12 patients per group. It is therefore difficult to establish the statistical significance of their results. The authors did not provide the raw data, instead referring to isolated percentage changes which were difficult to interpret. The Munday study was a more comprehensive study, with larger numbers. However some of the patients were recruited from Poland and they had not received optimal eczema therapy prior to the onset of the trial. These patients then received steroid and emollient creams, so their improvement might have been a result of the improved eczema management, rather then the anti-histamines. Despite this, there was still no difference between the two groups. There are no good quality studies investigating the efficacy of oral anti-histamines. Neither of the two studies reviewed showed any significant reduction in symptoms, nor did they demonstrate a statistical difference. We feel that the case was not proven either way for the use of antihistamines, but due to the flaws pointed out above, further trials are needed in children.

Clinical Bottom Line

Oral anti-histamines have not been shown to decrease symptoms of itch in children with atopic eczema. We should endeavour to optimise conventional treatment with liberal use of emmolients and appropriate strength of topical steroids, which is efficacious in reducing symptoms.

References

  1. Munday J, Bloomfield R, Goldman M et al. Chlorpheniramine is no more effective than placebo in relieving the symptoms of childhood atopic dermatitis with a nocturnal itching and scratching component. Dermatology 2002;205(1):40-5.
  2. La Rosa M, Ranno C, Musarra I, et al. Double-blind study of cetirizine in atopic eczema in children. Ann Allergy 1994 Aug;73(2):117-22.