Strengths and Difficulties Questionnaire

The Strengths and Difficulties Questionnaire (SDQ) is a self-report inventory behavioral screening questionnaire for children and adolescents ages 2 through 17 years old, developed by United Kingdom child psychiatrist Robert N. Goodman. The SDQ is available online, and has been translated into more than 80 languages, including Spanish, Chinese, Russian, and Portuguese.^[1] The PhenX Toolkit uses SDQ as its child protocol for General Psychiatric Assessment and for Broad Psychopathology.^[2][3]

There are three versions of the SDQ: a short form, a longer form with impact supplement, and a follow-up form designed for use after a behavioral intervention. The questionnaire takes 5–10 minutes to complete.

Scoring

The SDQ scoring site allows one to score paper copies of a parent, teacher and/or self-report and generates a brief report. 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).^[4] 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).

Total difficulty score

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.^[5] 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.

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 Youth in Mind, 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 Youth in Mind, with cut-offs chosen such that 80% of children score 'close to average', 10% are 'slightly raised', 5% 'high' and 5% 'very high'.

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%.

Prevalence estimates for UK research

UK researchers can use validated SDQ algorithms to convert a given SDQ mean score into a predicted prevalence of disorder in a group.^[6] This may be useful in translating research findings for policymakers or practitioners, or in assessing likely levels of need for child mental health services.

Scales

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. 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 preferable, 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)^[7]

Copyright

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 Youth in Mind 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 Youth in Mind 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 Youth in Mind to discuss arranging a full process of translation, back-translation and authorisation.

References

External links

• Official website
• SDQ scoring site
• Youth in Mind homepage