Strengths and Difficulties Questionnaire

The Strengths and Difficulty Questionnaire (SDQ) is a brief child mental health questionnaire for children and adolescents ages 2 through 17 years old, developed by the UK child psychiatrist Robert N Goodman. Detailed information about the SDQ can be found on the SDQ website, and is also possible to access versions of the SDQ in many languages from this site.

What the SDQ covers

It exists in several versions to meet the needs of researchers, clinicians and educationalists. Each version includes between one and three of the following components:

A. 25 items on symptoms related to mental health and behaviour

All versions of the SDQ ask about 25 attributes, some positive and others negative. These 25 items are divided between 5 scales:

  1. emotional symptoms (5 items) added together to generate a total difficulties score (based on 20 items)
  2. conduct problems (5 items)
  3. hyperactivity/inattention (5 items)
  4. peer relationship problems (5 items)
  5. prosocial behaviour (5 items)

The same 25 items are included in questionnaires for completion by the parents or teachers of 4- to 16-year-olds.[1]

A slightly modified informant-rated version for the parents or nursery teachers of 2- to 4-year-olds. 22 items are identical, the item on reflectiveness is softened, and 2 items on antisocial behaviour are replaced by items on oppositionality.

Questionnaires for self-completion by adolescents ask about the same 25 traits, though the wording is slightly different as it is in the first person (e.g. 'I often worry' instead of 'Many worries, often seems worried'). This self-report version is suitable for young people aged around 11-17, depending on their level of understanding and literacy.

B. An impact supplement

Several two-sided versions of the SDQ are available with the 25 items on strengths and difficulties on the front of the page and an impact supplement on the back. These extended versions of the SDQ ask whether the respondent thinks the young person has a problem, and if so, enquire further about chronicity, distress, impairment in everyday activities, and burden to others. This provides useful additional information for clinicians and researchers with an interest in psychiatric caseness and the determinants of service use.[2]

C. Follow-up questions

The follow-up versions of the SDQ include not only the 25 basic items and the impact question, but also two additional follow-up questions for use after an intervention of after visits to a clinic:

  1. How have the intervention / clinic visits changed the child's problems?
  2. Has the intervention helped in other ways, e.g. making the problems more bearable?

To increase the chance of detecting change, the follow-up versions of the SDQ ask about 'the last month', as opposed to 'the last six months or this school year', which is the reference period for the standard versions. Follow-up versions also omit the question about the chronicity of problems.

Complying with SDQ copyright: creating electronic versions and making translations

The Strengths and Difficulties Questionnaires, whether in English or in translation, are copyrighted documents that may not be modified in any way. Paper versions of the SDQ can be downloaded from the SDQ website in a wide variety of languages, and can be printed or photocopied without charge by individuals or non-profit organizations provided those organisations are not making any charge to families. No one except youthinmind is authorized to create or distribute electronic versions for any purpose - individuals or organisations wishing to create electronic versions (e.g. for a computer-administered survey) need to contact youthinmind and may need to pay a licence fee. It is also illegal to make or distribute unauthorised translations of the SDQ - individuals wishing to translate the SDQ to a new language should contact youthinmind to discuss arranging a full process of translation, back-translation and authorisation.

How to score the SDQ

The SDQ scoring site allows one to score paper copies of a parent, teacher and/or self-report SDQ free-of-charge, and generates a brief report. Instructions on how to score the SDQ oneself are available on the SDQ website. Briefly, each of the five scales of the SDQ are scored from 0-10, and one can add up four of these (emotional, conduct, hyperactivity and peer problems) to create a total difficulty score (range 0-40).[3] One can also add the emotional and peer items together to get an internalising problems score (range 0-20) and add the conduct and hyperactivity questions together to get an externalising score (range 0-20).

How to use the SDQ in clinical practice or in research

Total difficulty score

  1. Dimensional measure: The total difficulty score of the SDQ (range 0-40) is a fully dimensional measure, with each one-point increase in the total difficulty score corresponding to an increase in the risk of mental health disorder.[4] As such, one can use the total difficulty score as a dimensional measure in research, e.g. comparing mean scores between groups or as a continuous outcome in linear regression analysis.
  2. Categories based on single-informant symptoms scores: Alternatively, particularly when using the SDQ for screening purposes, it may be useful to turn symptom scores into categories. An initial three-category solution was proposed by youthinmind, the owner of the SDQ ('normal'/'borderline'/'abnormal') with the cut-offs chosen using normative data from large population-based UK studies. More recently, an alternative four-category solution has been adopted by youthinmind, with cut-offs chosen such that 80% of children score 'close to average', 10% are 'slightly raised', 5% 'high' and 5% 'very high' for details, see instructions on scoring the SDQ by hand.
  3. Categories based on multi-informant symptom + impact scores: The SDQ scoring website also allows one to categorise children according to their risk of ICD-10 or DSM-IV disorder based on triangulating information across all available informants (parent, teacher, self-report) and using the impact supplement as well as the symptom score. This is done for the disorder groupings 'any disorder', 'emotional disorder', conduct disorder' and 'hyperactivity disorder'. For each diagnostic grouping, there are three possible predictions: low risk, medium risk and high risk. In general, empirical studies show that for children defined as being at 'low risk' on the SDQ, around 1-4% turn out to have a disorder when assessed by experts. For children at 'medium risk' the proportion is 10-15%, and for children at 'high risk' the proportion is 25-60%.
  4. Prevalence estimates for UK research: Finally, UK researchers can use validated SDQ algorithms to convert a given SDQ mean score into a predicted prevalence of disorder in a group.[5] This may be useful in translating research findings for policymakers or practitioners, or in assessing likely levels of need for child mental health services.

SDQ scales

  1. When to use 5 subscales, when to use 2: One can also use the 5 scales of the SDQ either as dimensions (range 0-10) or else categorised into three- or four-categories in a similar was as is done for the total difficulty score see instructions for scoring the SDQ by hand. Alternatively, one can combine scales such that emotional+peer problems scales form a larger internalising scale (range 0-20) and the conduct + hyperactivity scales form a larger externalising scale (range 0=20). Research suggests that in low-risk groups (e.g. a general population sample) the latter approach may be prefereable, as there is less discrimination between the finer scales for lower scores (e.g. a child with a score of 2 on the hyperactivity scale is at increased risk of hyperactivity and behavioural disorder to a roughly equal degree). By contrast in high-risk samples (e.g. a clinic setting) the 5 finer scales may come into their own, as there is much more discrimination between them at higher scores (e.g. a child with a score of 7 on the hyperactivity scale is specifically at greater risk of a hyperactivity disorder, to a greater degree than they are at increased risk of a behavioural disorder)[6]

References

  1. ↑ Goodman, R., The Strengths and Difficulties Questionnaire: a research note. J Child Psychol Psychiatry, 1997. 38(5): p. 581-6
  2. ↑ Goodman, R., The extended version of the Strengths and Difficulties Questionnaire as a guide to child psychiatric caseness and consequent burden. J Child Psychol Psychiatry, 1999. 40(5): p. 791-9.
  3. ↑ Goodman, R., The Strengths and Difficulties Questionnaire: a research note. J Child Psychol Psychiatry, 1997. 38(5): p. 581-6
  4. ↑ Goodman, A. and R. Goodman, Strengths and difficulties questionnaire as a dimensional measure of child mental health. J Am Acad Child Adolesc Psychiatry, 2009. 48(4): p. 400-3
  5. ↑ Goodman, A. and R. Goodman, Population mean scores predict child mental disorder rates: validating SDQ prevalence estimators in Britain. J Child Psychol Psychiatry, 2011. 52(1): p. 100-8.
  6. ↑ Goodman, A., D.L. Lamping, and G.B. Ploubidis, When to use broader internalising and externalising subscales instead of the hypothesised five subscales on the Strengths and Difficulties Questionnaire (SDQ): data from British parents, teachers and children. J Abnorm Child Psychol, 2010. 38(8): p. 1179-91.

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