A retrospective evaluation of azathioprine in severe childhood atopic eczema, using thiopurine methyltransferase levels to exclude patients at high risk of myelosuppression.
BACKGROUND
Atopic eczema is a chronic inflammatory skin disease, which in most children can be adequately controlled using topical therapy. However, in a small number of children it is necessary to use systemic treatments to gain an acceptable level of disease control.


OBJECTIVE
To evaluate azathioprine as a treatment for severe atopic eczema in children, and the value of pretreatment thiopurine methyltransferase (TPMT) levels in the identification of patients at high risk of myelosuppression.


METHODS
Between January 1997 and May 2000, 91 children had erythrocyte TPMT assays with the intention of treating their atopic eczema with azathioprine. This study is based on retrospective examination of data taken from the hospital notes of these children, who had attended Great Ormond Street Hospital for Children and St John's Institute of Dermatology, London.


RESULTS
The distribution of TPMT values corresponded closely to that previously described in adults. Forty-eight children were commenced on treatment with azathioprine. Twenty-eight had an excellent response to treatment, 13 had a good response and seven had a poor response. No patient developed neutropenia.


CONCLUSIONS
Azathioprine may prove a very valuable treatment for severe atopic eczema in children. We consider its short-term adverse effect profile in children with normal TPMT activity to have been entirely acceptable with our treatment protocol. As result, we now feel confident to initiate therapy at dose levels of 2.5-3.5 mg kg(-1) in those with a normal TPMT level, and to reduce the frequency with which we undertake tests of bone marrow and liver function.
Murphy
L-A
LA
Department of Dermatology, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH, UK.
Atherton
D
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D001379:Azathioprine / Q000009:adverse effects / Q000627:therapeutic use*; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003876:Dermatitis, Atopic / Q000188:drug therapy* / Q000201:enzymology; D004359:Drug Therapy, Combination; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects / Q000627:therapeutic use*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008780:Methyltransferases / Q000097:blood*; D018579:Patient Selection; D011239:Prednisolone / Q000627:therapeutic use; D012189:Retrospective Studies; D018570:Risk Assessment
D015415:Biomarkers; D007166:Immunosuppressive Agents; D011239:Prednisolone; D008780:Methyltransferases; C022745:thiopurine methyltransferase; D001379:Azathioprine