The 10-item Autism Spectrum Quotient, known as the AQ-10, is an international screening method recommended by the National Institute for Health and Care Excellence (NICE).

The AQ-10 is a 10-point scale which is used in conjunction with other methods to make autism referrals and diagnoses. The patient will be asked to state whether they agree or disagree to statements such as “I find it difficult to work out other people’s intentions”. Their answers are then used to produce a score out of ten; a higher score represents more autistic traits.

This technique is widely used by health professionals globally. However, a recent report published in The Lancet Psychiatry, has found a “worrying discrepancy” between the clinical cut-off recommended by NICE and the research informing their guidance.

A score of 6 or above on this scale should signal that the patient needs to be referred to a specialist psychologist or psychiatrist. However, the report found that NICE guidelines have incorrectly been recommending a score of ‘more than 6 out of 10’. This error means that many people who scored 6 out of 10 may not have received the help and support that they require.

The psychologists who discovered the error were shocked at the findings, seeing as these guidelines have been in place for nearly a decade. The researchers said that the use of an inappropriately high cut-off score makes this autism screening tool less sensitive and therefore less accurate.

Erroneous guidelines will have contributed to missed autism referral

Lucy Waldren, lead author of the article from the Department of Psychology at Bath, said: "Our examination of the literature has discovered that the erroneous NICE guidelines have caused major confusion amongst researchers on which cut-off scores to use. We have found several examples of the incorrect value being applied. Participants in studies have also been inappropriately excluded based on their scores. And, even when the correct value was used, it has been incorrectly attributed to the NICE guidance.

"If researchers have followed the incorrect NICE guidelines and used the AQ-10 incorrectly in their studies, they may need to reanalyse and republish, or even consider retracting their findings."

The researchers say that the erroneous guidelines will have undoubtedly contributed to missed autism referrals, diagnoses and opportunities for intervention and support. Although the AQ-10 technique is not the sole method when it comes to diagnosing autism, it is a factor of the clinician’s decision-making process.

For this reason, the psychologists are calling for an urgent review of the NICE guidelines, so that pending diagnoses are not missed and that any errors in previous screenings can be corrected. In their paper, they recommend that clinicians and researchers use the cut-off score of “6 or above” instead of NICE’s “more than 6 out of 10” to inform their work.

Dr Punit Shah, Associate Professor of Psychology at the University of Bath and the GW4 Neurodevelopmental Neurodiversity Network, said: "This is a worrying finding as cut-off scores on screening tools underpin their accuracy. Although a difference of 1-point might not seem huge, a 1-point increased cut-off score on a 10-point scale is substantial and makes the instrument less psychologically sensitive. This means that many people going to their GPs who genuinely have autism - perhaps scoring 6 on the scale - are currently less likely to be referred to specialists for full diagnostic assessment. Diagnosis is of course crucial: without a diagnosis, people have less access to appropriate interventions and support, even certain benefits.

"It is impossible to put a number on exactly how many people will have been affected by this, but it is well known that delayed referrals and late diagnoses of autism have negative consequences for the mental health and wellbeing of autistic people and their families. We urgently need to do all we can to raise awareness of this issue, among GPs and other clinicians, while the NICE guidelines are corrected. NHS waiting times for autism assessments are already far too long and these flaws in screening procedures will be compounding this issue."