6 Implications for the NHS
6.1 The guidance will affect only a small proportion of people with atopic eczema who have moderate or severe forms of the disease (see Section 2.3). It is not clear what proportion of people with moderate or severe disease currently experience an unsatisfactory clinical response to adequate use of the maximum strength and potency of topical corticosteroid that is appropriate for their age and the area being treated and who are at serious risk of developing important adverse effects from further topical corticosteroid use such as permanent skin atrophy. It is therefore unclear what proportion of people with moderate or severe atopic eczema would use tacrolimus or pimecrolimus under this guidance. For pimecrolimus, this is further complicated by the lack of information on the number of children with moderate atopic eczema that has not been controlled by topical corticosteroids and who are affected by the disease on the face and neck.
6.2 The cost per gram of topical corticosteroids (3–14p) is small compared with the cost per gram of tacrolimus (62–68p) and the cost per gram of pimecrolimus (59p). By varying estimates around the cost of topical corticosteroids and the quantity used, a crude calculation suggests that the additional cost per year per patient compared with topical corticosteroids would lie between £538 and £1192 for tacrolimus and between £511 and £1117 for pimecrolimus. However, these estimates assume that all other treatment costs, such as the number of visits to physicians, the incidence of adverse effects such as infections and the quantity of the topical immunomodulators required, compared with topical corticosteroids, would remain the same.
6.3 Using the above estimates, the additional spending in a Primary Care Trust (PCT) with a population of 100,000 people was calculated crudely, assuming different levels of uptake with tacrolimus and pimecrolimus. The calculations assumed the point prevalence of atopic eczema to be 13.4% (based on a prevalence study in the UK in 1996), that 14% of people with atopic eczema have moderate disease and that 2% of people with atopic eczema have severe disease. On the basis of these assumptions, the estimated additional annual spending in a PCT this size would be:
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between £11,500 and £25,600 if 1% of people currently using topical corticosteroids with moderate or severe disease need to switch to tacrolimus, and between £9600 and £21,000 if 1% of people with moderate disease need to switch to pimecrolimus (in this case, children with atopic eczema on the face or neck)
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between £23,100 and £51,100 if 2% of people currently using topical corticosteroids with moderate or severe disease need to switch to tacrolimus, and between £19,200 and £41,900 if 2% of people with moderate disease need to switch to pimecrolimus (in this case, children with atopic eczema on the face or neck)
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between £57,700 and £127,800 if 5% of people currently using topical corticosteroids with moderate or severe disease need to switch to tacrolimus, and between £47,900 and £104,800 if 5% of people with moderate disease need to switch to pimecrolimus (in this case, children with atopic eczema on the face or neck).
Given the number of assumptions involved in the calculations, these estimates should be interpreted cautiously. In addition, it is known that 610,000 prescriptions for tacrolimus with a total net ingredient cost of £2,260,300 and 21,650 prescriptions for pimecrolimus with a total net ingredient cost of £652,900 were issued in England during 2003. It has therefore been estimated that a PCT with a population of 100,000 would have spent around £4500 on prescriptions for tacrolimus and around £1300 on prescriptions for pimecrolimus during this time.