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1. Indentification

1.2 Screening and Identification

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Clinical Questions

1. Should screening for ADHD occur at a population level?
2. Should screening for ADHD occur in high-risk populations?

Clinical practice gaps, uncertainties and need for guidance

There is evidence that ADHD is underdiagnosed internationally and in Australia (Asherson et al., 2012; Deloitte Access Economics, 2019; Ginsberg, Quintero, Anand, Casillas, & Upadhyaya, 2014; Sciberras, Streatfeild, et al., 2020). Failing to provide people with a diagnosis of ADHD, and therefore failing to offer effective treatment, carries a high cost (Asherson et al., 2012; Deloitte Access Economics, 2019; Ginsberg et al., 2014; Sciberras, Streatfeild, et al., 2020). Early identification of people with ADHD is needed to allow for early intervention to occur as early in life as possible, to reduce impacts on functioning and maximise positive outcomes.

Whether to screen for ADHD at a population level needs to be considered. This includes exploring the sensitivity and specificity of screening tools, and the benefits and costs of screening in identifying true cases and false positive cases to the healthcare system, individuals and their families.

It is also well established that certain groups are at much higher risk of developing ADHD (see question 2.3). Costs of screening high-risk groups are therefore likely to be less than screening the general population, but screening may be similarly limited by the sensitivity and specificity of tools, and costs and burden to the healthcare system of screening. Guidance is thus required as to whether screening for ADHD should occur at a population level or within high-risk populations.

Summary of narrative review

Screening can include population-based screening, where the screening test is offered to all individuals within a target group (such as all children attending primary school), or targeted risk screening is performed in high-risk groups. Surveillance involves the ongoing gathering of information to identify a condition. A screening test may involve risk scores on a rating scale, observation of signs and symptoms or laboratory tests.

There are various screening tools for ADHD (Box 1). These include clinician observation, self-report, parent-report, teacher report or other informant-report. For children and adolescents, screening tools include (but are not limited to) the Conners’ Rating Scales and Strengths and Difficulties Questionnaires, and for adults, the Adult ADHD Self-Report Scale (ASRS). The reliability and validity of such tests need to be carefully established to prevent positive screening for individuals who do not have ADHD (false positives), which would increase healthcare costs while ensuring accurate identification of true cases so individuals with ADHD do not go undetected in the screening process (false negatives).

Sensitivity, or the true positive rate, is the proportion of people with ADHD who are correctly identified. Specificity, or the true negative rate, is the proportion of people without ADHD who are correctly identified as such. Acceptable levels of sensitivity and specificity are usually both set at around 80%, which may depend on the population being screened and the associated costs and benefits of different levels. Thus, if sensitivity is 80%, this means 20% of true cases of ADHD are missed. A specificity of 80% means that 20% of positive screeners will not actually have ADHD. Often, as the sensitivity of a measure increases, the specificity decreases, resulting in a high number of false positives.

Box 1 shows examples of commonly used rating scales used for screening for ADHD. These are provided for illustrative purposes only and are not an exhaustive list. The sensitivity and specificity of each rating scale in the proposed setting should be carefully reviewed by the clinician before use.

Box 1 Example ADHD screening rating scales.

Young children

  • Achenbach System of Empirically Based Assessment – Attention Problems scale
  • Child Behaviour Checklist DSM Oriented ADHD subscale

 

Children and adolescents

  • Achenbach System of Empirically Based Assessment – Attention Problems scale
  • Child Behaviour Checklist – DSM Oriented ADHD subscale
  • Strengths and Difficulties Questionnaires (Hyperactivity subscale)
  • Conners’ 3 short form
  • Swanson, Nolan and Pelham (SNAP) scale
  • ADHD Rating Scale
  • Vanderbilt ADHD Diagnostic Rating Scale

Adults

  • WHO Adult ADHD Self Report Scale (ASRS) (Part A)
  • Conners’ Adult ADHD Rating Scale – Short
  • Wender Utah Rating Scale (WURS) – Short

Children and Adolescents

A recent systematic review and meta-analysis (Mulraney et al., 2021) explored screening tools for ADHD in children and adolescents. They found none of the screening tools met acceptable levels of sensitivity and specificity (defined as both over 80%). Their meta-analysis comparing high-risk with community-based study populations found no significant difference in both sensitivity and specificity. Thus, current screening tools for children and adolescents do not meet acceptable sensitivity and specificity rates for universal screening. While ADHD is likely underdiagnosed and undertreated in Australia, there is a lack of accurate ADHD screening tools to enable cost-effective population-based screening in children and adolescents.

Adults

In adults, a number of ADHD screening tools exist (Taylor, Deb, & Unwin, 2011), including the World Health Organization-developed Adult ADHD Self-Report Scale (ASRS) and the Wender Utah Rating Scale (WURS). The ASRS was explored in one study with sensitivity and specificity rates below 80% (Kessler et al., 2005) for the general population.

One study of individuals with ADHD and randomly selected controls from the population found both sensitivity and specificity levels at 80% and above for both the ASRS and WURS. There was better performance by the longer WURS than the ASRS for specificity at higher sensitivity levels (Brevik, Lundervold, Haavik, & Posserud, 2020). Other studies of the DSM-5 version of the ASRS, ASRS-5 have found both specificity and sensitivity levels above 80% in non-clinical controls (Baggio et al., 2021; Ustun et al., 2017).

There have been various studies of ADHD screening tools in higher-risk groups. In individuals with major depression, the ASRS-v1.1 showed both specificity and sensitivity below the required levels (Dunlop, Wu, & Helms, 2018). There was acceptable sensitivity but no specificity in studies of substance use disorders (Daigre & Ramos-Quiroga, 2009; Van de Glind et al., 2013) and incarcerated women (Konstenius, Larsson, Lundholm, Philips, van de Glind, Jayaram-Lindström, et al., 2015).

A modified version of the Barkley Adult ADHD Rating Scale (BAARS-IV) did have the required sensitivity and specificity levels in adult prison inmates (Young, González, et al., 2016). Studies of the ASRS-5 found acceptable sensitivity but not specificity in individuals with bipolar disorder and/or borderline personality disorder (Baggio et al., 2021) and other clinical groups (Ustun et al., 2017).

False negatives may also be an issue in substance abuse disorders such as alcohol abuse (Luderer et al., 2019). Thus, the screening measures may have difficulties differentiating adult ADHD from other psychiatric conditions that have similar or overlapping symptoms.

Population-level screening

It is acknowledged that there may be frequent underdiagnosis of ADHD in a range of education (primary, secondary or tertiary) and health settings. However, based on the levels of screening test accuracy noted above, universal screening for ADHD should not occur at the population level (for example, in preschools, primary and secondary schools and universities/TAFEs).

High-risk group screening

While there is an increased risk of ADHD in certain high-risk groups (see 2.1), accurate screening tools are lacking for some groups. Commonly used ADHD screening measures may result in low specificity (for example, high false positives) in high-risk groups such as those with other mental health conditions with overlapping symptoms. However, the cost associated with allowing people with ADHD in high-risk groups to remain undiagnosed and untreated likely outweighs the costs of screening in this subpopulation.

Services and clinicians should be aware of the risk of identifying false positives and the implications for their services, such as additional assessment costs, and the benefits of identifying people with ADHD, should they choose to implement screening. Positive screening should be followed by further assessment for ADHD. Additional research on screening tools needs to be conducted to establish higher levels of sensitivity and specificity.

Importantly, ADHD screening tools have not been validated in some high-risk groups, such as Aboriginal and Torres Strait Islander peoples, individuals with acquired brain injury and those with suicidal ideation. The reliability and validity of using existing ADHD screening tools in these groups is unknown.

Recommendations

Clinical considerations for implementation of the recommendations

A high number of people screening positive for ADHD places a burden on the healthcare system to assess, diagnose and treat these individuals. In the absence of an accurate screening tool, ‘false positives’ increase the burden on assessment services, resulting in wasted resources and associated costs.

The reliability and validity of screening instruments need to be improved to avoid unnecessary costs for the assessment of false positives and failure to identify true positives. Services should conduct screening in high-risk groups based on their own cost-benefit analysis of the measures they choose for screening.

Screening has not been studied in subgroups such as Aboriginal and/or Torres Strait Islander peoples or cultural and linguistically diverse communities, and this lack of evidence is likely to affect health equity. People with ADHD within these subgroups or in groups with lower socio-economic status may remain under-diagnosed.

See Technical Report, section 2.4 for further details

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