Why is UK and Australia high risk results for DS different?

[Worried1994]

Hi,

just wondering if anyone knows why the high risk Down syndrome probability is different in the UK and Australia?

UK considers anything 1:150 (150 or below) high risk

Australia considers anything 1:300 (300 or below) high risk

Not sure. But there is hardly any difference between the rates in both countries.

I didn't know this. I can only guess its related in part to funding (eg offering future tests) and a value judgement on what's an acceptable risk. I don't think there is a universal medical definition of high risk.

I wonder if Australia offers the NIPT as standard?

The 1:150 being the trigger for the option of an invasive test was based on the risk of miscarriage for amniocentesis (although I believe this also may be out of date because of better imaging etc) - i.e it wasn't considered appropriate to offer a test where the risk of miscarriage outweighed the odds of a positive diagnosis.

If you were offering a non-invasive test first then that would change the calculation since it would be based on resources and not risk of miscarriage.

@ditalini that's a really good point about weighing against the invasive test risk

I’m in London and it’s different in different trusts. In the hospital where I had my first two high risk was 1:150. I’m a couple of miles down the road and they class high risk and offer NIPT if you are below 1:500.