To the Editor: There appear to be regional differences in the prescribing of amino acid infant formula in Australia. This is possibly due to differing practices in use of this formula as a first-line treatment for cow’s milk allergy or as a strategy for preventing allergy. This has financial implications, as the cost to the Pharmaceutical Benefits Scheme (PBS) of amino acid formula is $371 per prescription, compared with $106 for hydrolysed protein formula.1

In infants at high risk of allergic disease who are unable to be completely breastfed, there is evidence that prolonged feeding with a formula based on hydrolysed cow’s milk protein rather than conventional cow’s milk formula reduces infant and childhood allergy.2,3 There is no clear evidence that amino acid formula should be substituted for extensively hydrolysed protein formula as a primary preventive strategy.3

The current PBS indication for hydrolysed protein formula is treatment of intolerance to both cow’s milk and soy protein, but not primary allergy prevention. Similarly, current PBS guidelines restrict the use of amino acid formulas to proven intolerance to cow’s milk, soy protein and protein hydrolysate. Among children who are allergic to cow’s milk, 10% or less are also sensitive to protein hydrolysate formula.4 Thus, if current guidelines were followed, one might expect nine times the use of hydrolysed protein formula compared with amino acid formula.

I obtained statistics on PBS items supplied for the period January 2003 to January 2004 from the Health Insurance Commission (www.hic.gov.au/statistics/dyn_pbs/forms/pbs_tab1.shtml) for hydrolysed protein formula (item numbers 2676W and 8259Q) and synthetic amino acid formula (item numbers 3066J, 8443J, 8574G and 8575H). These showed that 8374 hydrolysed protein formula items were supplied, half the number of amino acid formula items (16 886).

Numbers of amino acid formula items supplied per 1000 children aged 4 years and younger were calculated using population statistics from the Australian Bureau of Statistics census figures 2001. These are compared in the Box with numbers of paediatric physicians per 1000 children (obtained from the Royal Australasian College of Physicians 2004) and paediatric allergists (derived from the Australasian Society of Clinical Immunology and Allergy membership handbook 2003).

Prescribing practice varied markedly between states and territories. The Australian Capital Territory, New South Wales and Victoria had six to seven times more amino acid formula items per 1000 children than Western Australia. This did not appear related to numbers of paediatricians or paediatric allergists, as Western Australia had a similar number of paediatricians and more paediatric allergists per 1000 children than NSW and Victoria.

The differences found were unlikely to be related to variation in numbers of adult immunology/allergy specialists, who are unlikely to treat many infants aged under 2 years. Nor were they likely to be due to differing prevalence of combined milk, soy and protein hydrolysate intolerance, as the prevalence of allergic disease does not differ markedly between Australian states. For example, the prevalence of atopic eczema at age 6 years in four cities (Adelaide, Melbourne, Sydney and Perth) was very similar, ranging from 10.1% to 11.4%.5 It seems unlikely that 80% of cases of combined intolerance are being missed in Western Australia. The estimated cost to the PBS for amino acid formula for 2003–2004 of $7 107 627 was 10 times that of hydrolysed formula ($757 570).