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Selecting screening tools

From: Concurrent Substance Use and Mental Health Problems in Youth: Screening for Concurrent Substance Use and Mental Health Problems in Youth (© 2009, CAMH)

There is no shortage of research literature dedicated to special issues and sub-topics related to screening and assessment of mental and substance use disorders among children and adolescents. The following points are most critical to understanding the choices made in this project. They guided the review and synthesis of information on various tools and they will influence the choice and implementation of tools in clinical or preventive contexts:

  • screening and assessment are steps in a sequential, staged process
    • screening raises a red flag
    • screening can be a two-step process
  • unique contexts and requirements for youth
  • program setting will determine criteria (performance of a given test is dependent on the context in which it is implemented). The criteria include:
    • agency mandate 
    • characteristics of the target population 
    • purposes to which the results will be put
    • client engagement, motivation and the therapeutic alliance
    • availability of resources
    • policy and research requirements

Screening and assessment are steps in a sequential, staged process

Screening and assessment are components of a staged process that aims to identify and measure the mental health and substance use-related needs and behaviours of children and adolescents. It can be difficult to determine precisely where screening ends and assessment begins.

Screening raises a red flag

A screening process is intended to be an efficient way of raising a "red flag" about the possibility of a particular disorder or problem area, and a need for a more detailed assessment that informs service planning. In most service delivery settings it would be a waste of scarce resources to implement a full-blown mental health and/or substance use assessment for all children and adolescents presenting for help. Similarly, in a preventive context, it would be a waste of resources to implement preventive services for those who do not truly need them.

Screening provides what Grisso and colleagues (Grisso et al., 2005)2 refer to as "economical identification" whereas follow-up assessment refers to "more extensive and individualized identification of mental health [and substance use] needs of those youth whose screening results warrant future investigation" (Grisso et al., p. 12). The two processes may be aimed at essentially the same target conditions (i.e., mental health and substance use disorders) but screening does so much more tentatively.

Screening also tends to be done universally (i.e., virtually all clients) whereas assessment is a more selective and targeted process. Lastly, the results of the screening process imply the need for immediate action (typically additional assessment but perhaps also referral and linkage to other services). While assessment may identify immediate needs, it is usually more concerned with longer-term treatment planning and service coordination.

Screening and assessment tools

It is not the number of questions or administration time that make one tool a screener and another an assessment instrument. Some screening tools have the look and feel of more comprehensive assessment tools simply because they are lengthy and comprehensive in the coverage of disorders or problem domains. Some assessment tools may actually be briefer than some screening tools if the assessment tool focuses only on specific disorders, and the screening tool is multidimensional in its coverage. It is also important to distinguish between the screening or assessment tool and the screening or assessment process. Calling something a "screening tool" does not make it one–it depends on how it has been developed, for what purpose, and how it is linked to further assessment processes that will confirm or disconfirm the screening results.

Two-step screening

We have looked at a "two-staged" model of screening and assessment. It is also possible, however, to conceptualize the first stage–screening–as involving two distinct steps. Some mental health and substance use screening tools are designed to identify the possibility that the child or adolescent has any disorder, whereas other screening tools are much more specific, and aim in the one instrument to tentatively identify one or more specific disorders. So, a screening process may include two steps:

  1. applying a very brief tool to determine "generalized caseness"
  2. a longer, more comprehensive tool to determine what could be called "disorder-specific caseness."

For example, a screening protocol for adults might use the brief GAIN-Short Screener or the K6 in step one and, depending on the results, follow up with the longer, 131-item Psychiatric Diagnostic Screening Questionnaire in step two to tentatively identify one or more very specific disorders. The goal of a very brief screening tool followed by a more comprehensive tool working together would be to use subsequent, and even more costly, assessment resources judiciously and efficiently.


Figure 1: A Staged Approach to Screening and Assessment


Brief Description  

Stage 1: Screening–Tentative identification of generalized caseness 

Brief screen for possibility of any substance use or mental disorder 


Grey arrow pointing down

Stage 2: Screening–Tentative identification of disorder-specific caseness 

Longer screen for specific substance use or mental disorders 


Grey arrow pointing down

Stage 3: Assessment–Confirmation of specific disorders 

Diagnostic assessment and treatment planning 


Unique contexts and requirements for youth

Screening tools designed for adults will not necessarily be appropriate and useful when used with children and adolescents. Mental disorders of adolescents, including substance use disorders, are not just "less mature" versions of adult disorders (or "older" versions of childhood disorders). They vary at different stages in the life course, and these differences evolve over time.

The main implications of the developmental perspective for screening tools and processes are:

  • emotions or thoughts that might be considered "normal" at one age may be "abnormal" at another
  • some disorders of childhood and adolescence may continue into adulthood if untreated but other disorders will not (discontinuity). Discontinuity also applies to emotional states independent of a specific mental disorder, with the instability of mood in adolescence being particularly noteworthy. One implication is the need for periodic rather than one-time screening and assessment
  • the likelihood of identifying more than one mental disorder is thought to be much higher in children and adolescents compared to adults. This may be a function of how disorders are defined for children and adolescents, and also that psychopathology is just more complex
  • factors such as gender differences are particularly critical (e.g., boys more likely to experience externalizing disorders and girls more likely to have internalizing disorders). Gender differences also increase with age, with girls overtaking boys in terms of prevalence of mental disorder as they move into the later years of adolescence. Cultural and socio-economic differences are also important.

Program setting and needs will determine criteria

Agency mandate

The expectation and overall performance of a given test is also highly dependent on the context in which it is used. There are many doorways into mental health and/or substance use services and supports. These include specialized mental health and substance use services, primary care (including pediatric specialists and emergency services), family and children's services, social assistance, justice-related programs and institutions, and schools. The characteristics of the target population and the screening objectives vary with the treatment setting.

In most cases, when young people present to specialized substance use services a screening tool for substance use disorders is not needed. There is, however, a need for a screening tool that will help identify mental disorders. Similarly, a screening tool for substance use disorders is usually needed when children and adolescents present to mental health services. These specialized settings may be more motivated to implement the three-stage screening and assessment process identified above, and thus commit to the longer, more comprehensive screening tools that might not be practical for more generic health and social services.

Characteristics of the target population

The characteristics of the target population seen by various service delivery settings, and in particular, the age range of the population, will be critical to the selection of the screening tools. The younger the person, the greater the need to use tools that can be completed by a parent or perhaps a teacher. Most tools aimed specifically at adolescents are based on self-report, as is the case with adults.

Purpose or purposes to which the results will be put

Grisso and colleagues (2005) emphasize that a given service that is considering the implementation of a screening process for mental and/or substance use disorders should clearly articulate how the results of the screening process will be used. They identify three main objectives:

  • improving staff decision-making
  • fulfilling regulatory requirements and professional standards
  • managing resources.

Improving staff decision-making

Improving staff decisions is the most common reason for implementing a standard screening process. This goal relates back to the value of a two- or three-stage screening and assessment process as an aid to improved, and very individualized, treatment and support planning. While the goal in choosing a screening tool is to minimize the need for special qualifications or training, this will depend on how structured the tool is (i.e., how fixed or flexible the format for test administration), as well as the simplicity of tool itself (i.e., response categories and scoring procedures). Tools vary widely with respect to computerized versus manual scoring and the extent to which results may be "normed" for different subgroups, such as boys versus girls, or different age ranges. It is absolutely essential that the plan for using the results of a screening tool be prepared, documented in agency policy and procedures, widely communicated and adequately monitored and reinforced.

Regulatory requirements

Services may be required to screen for other types of problems (e.g., suicide risk or other safety needs). Services that have a long list of health and social problems to screen for will likely opt for brief screening tools for substance use and mental health problems.

Managing resources

Managing resources is the third area mentioned by Grisso and colleagues (2005). Examples include adjusting staff complements and skills to ensure coverage in particular topic areas, ensuring adequate linkages are in place with outside agencies for certain types of problems areas, and lobbying for additional funding.

Outcome monitoring

A fourth reason for screening, related in part to those articulated by Grisso and colleagues, is outcome monitoring. Some, but not all, screening tools are appropriate for this function. If the items are properly structured (e.g., aimed at symptoms or concerns that are recent rather than over the lifetime), and if the information that the tool provides is linked to the services that that client receives, it should be possible to link the screening function with outcome assessment.

Client engagement, motivation and the therapeutic alliance

Another aspect of the clinical application of a screening tool is the relationship between the question and answer format of a screening tool and the process of client engagement, motivation and therapeutic alliance. An effective screening process depends on having a good tool to use, but also on the competence of the staff in using it with clients in a non-threatening and engaging manner.

Availability of resources

Other contextual factors associated with choosing and implementing a screening tool include the availability of financial resources to acquire tools that are available only on a pay-per-use basis, the information infrastructure to support computerized administration, and adequate Internet access for online scoring and feedback.

The level of expertise required for administration, scoring and interpretation of screening tools varies significantly. The more comprehensive screening tools typically used in a three-stage screening and assessment model will require more training and expertise than the briefer tools commonly used in a two-stage model.

Policy and research requirements

Policy-related factors may be internal to the treatment service (e.g., adjusting internal policies related to the flow of clients through the internal delivery pathway) or external (e.g., calling for inter-agency agreements on how those with particular problems or disorders will be case-managed or referred). Internal policy issues also relate to the extent to which it is mandatory for all staff to use the screening tool(s) on a routine basis. Some staff will be "pro-tool" while others may strongly oppose their use, often because they feel that tools interfere with establishing good rapport with clients and their families. Although the factors underlying these differences in perception are not well-understood, the differences are critically important for systematic and sustainable use of any tool regardless of its psychometric performance.

At a regional or provincial level, a particular screening tool may be mandated for purposes of consistency in communication, public health surveillance, and/or performance monitoring.

Research objectives (e.g., monitoring trends over time in the characteristics of service recipients in relation to trends in the general population) may also influence the choice of screening tool. In this case policies should be in place that outline how the results can be used and whether, and how, others can access the results for purposes other than those for which the data were originally gathered.


2. Grisso, T., Vincent, G. & Seagrave, D. (Eds.) (2005). Mental Health Screening and Assessment in Juvenile Justice. New York: Guilford Press.