Risking over diagnosis

March 4, 2019 | Academic | ADHD, Insights

Pediatricians see a significantly higher percentage of referrals involving the youngest children in a school year for ADHD diagnoses and treatments.

Objective data can be used to remove this bias and prevent the overdiagnosis of children who are simply young for their year. ADHD decision making is already compromised by the complex nature of the disorder, associated conditions and reliance on subjective information which can be ambiguous and biased, leading to diagnostic delay and concern about under and overdiagnosis.

In the field of pediatric ADHD there is an additional complication as children are often compared against their peers (as in other health assessments and academic performance) and pupils who are considered as lower achievers or more “difficult” to manage by their teachers may also display some of the signs of inattention, impulsivity or hyperactivity which characterise ADHD. In fact, one of the main reasons children are referred for ADHD assessment is a difference in their behaviour compared to their classmates. In a referral process, teachers are tasked with using subjective rating scales to assess the behaviours associated with ADHD which is an important input to the diagnostic process.

However, when it comes to identifying potential ADHD, classmate comparisons are problematic as pupils in the same school year vary in age by 12 months. Research from Canada, Sweden and Taiwan shows that the youngest children in a school year are significantly more likely to be referred for assessment, receive a diagnosis, and be treated for ADHD than those who are up to 12 months older [1,2,3] .

At Qbtech we compared data from our market leading ADHD test product QbTest and found that younger children are 37% more likely to be tested – which is strongly supportive of the findings below.

Risking over diagnosis

These children may simply be displaying signs of relative immaturity, resulting in referral bias and increasing the risk of over-diagnosis.

QbTest reports are generated by comparing an individual’s results with benchmark data from people of the same gender and age without ADHD. This removes age and gender bias. Critically, when we look at QbTest performance for children who are young for their school year, we see no difference in Hyperactivity, Impulsivity or Inattention when compared to their older peers.

Adding an objective ADHD test to the pediatric assessment process will reduce the risk for over and under-diagnosing ADHD and lead to a more appropriate use of ADHD medicines in children.


[1] Chen, MH. et al. (2016). Influence of relative age on diagnosis and treatment of attention-deficit hyperactivity disorder in Taiwanese children. Journal of Pediatrics, 172, 162-167.

[2]Halldner, L. et al. (2014). Relative immaturity and ADHD: findings from nationwide registers, parent- and self-reports. Journal of Child Psychology and Psychiatry, 55, 897-904.

[3]Morrow, R. L. et al. (2012). Influence of relative age on diagnosis and treatment of attention-deficit/hyperactivity disorder in children. Canadian Medical Association Journal, 184, 755-762.

Related Blogs

01 Jun

Evaluating ADHD in primary care – objectively

1-minute summary: This case study shares the story of how the Sunlight Group Practice in the Wirral, Merseyside, is the...
05 Apr

Living with ADHD and the importance of early diagnosis

Kent Surrey and Sussex Academic Health Science Network (KSSAHSN), a part of the wider Academic Health Science Network (AHSN) have...
26 Jan

Dr. Theresa Cerulli on the importance of standardizing ADHD care

1-minute summary: Dr Theresa Cerulli has been specialising in ADHD for 20 years. In this interview, Dr Cerulli reflects on...