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Soaring autism rate caused by shift in diagnostic habits

By Emma Wilkinson

The massive rise in autism cases over the past decade has been caused by a shift in diagnostic habits ­ and not by MMR vaccine, according to a new study of records from 250 GP practices across the UK.

The analysis of data on boys aged two to five from the General Practice Research Database concluded that the incidence of autism has soared from 1.6 per 10,000 born in 1993 to 9.5 per 10,000 born in 1999.

But this rise was accompanied by a decline of a similar scale in diagnoses of

other developmental disorders.

The researchers, from the Boston University School of Medicine, said the findings suggested the overall incidence of developmental disorders had remained roughly stable but that GPs and specialists were labelling an increasing proportion as autism.

This latest boost in the

drive to convince parents of MMR safety comes at a welcome time for GPs, with MMR uptake set to become a PCT star ratings indicator from April. This move is expected to put practices under renewed pressure to bolster uptake of the vaccine.

The new study, published in Pharmacotherapy (January), also found there were no differences in the medical, drug or vaccination histories of boys diagnosed with autism between 1992 and 2000 and the histories of matched boys without the condition. However, boys with autism were more likely to have sensory disorders such as hearing loss.

The researchers said behavioural disorders were now much more likely to lead to a diagnosis of autism than a decade ago.

They added: 'The incidence of diagnosed autism has risen greatly since the late 1980s but MMR vaccination is not the cause.'

An accompanying editorial said the research 'completed the jigsaw puzzle' and meant parents and health professionals could have confidence in the safety of MMR.

Dr George Kassianos, RCGP immunisation spokes-man and a GP in Bracknell, Berkshire, said the findings 'confirm what GPs have always thought'.

He said every additional piece of evidence supporting MMR safety made GPs feel more 'comfortable' when reassuring parents.

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