ICIQ Validation and Translation Guidance

Validation methodology

ICIQ questionnaires have historically been developed using established classical psychometric methods. Our approach continues to evolve alongside developments in patient-reported outcome measurement. The methods used depend on the construct being assessed, the intended use of the questionnaire and its proposed scoring structure. Evaluation may include the following measurement properties.

Content validity

Content validity considers whether a questionnaire adequately reflects the symptoms, experiences or impacts it is intended to measure, and whether its items are relevant, comprehensive and understandable to the target population.

Patient involvement is central to this process and may include qualitative interviews during item development and cognitive interviews to explore how questions and response options are understood. Input from clinicians and other relevant stakeholders may also contribute to ensuring appropriate clinical and conceptual coverage.

Structural validity

Where questionnaire items are intended to contribute to one or more scores or domains, the underlying structure of the questionnaire should be evaluated.

Methods such as exploratory and confirmatory factor analysis may be used to assess whether relationships between items support the proposed scoring structure. Item response theory or Rasch methods may also be appropriate for some questionnaires and constructs.

Internal consistency

Internal consistency considers the extent to which items within a scale or domain are related to one another. Measures such as Cronbach's alpha or other appropriate reliability coefficients may be used. Internal consistency should be interpreted in the context of the underlying structure of the questionnaire rather than considered in isolation.

Test-retest reliability

Test-retest reliability assesses the stability of questionnaire scores when the measure is repeated in people whose condition is not expected to have meaningfully changed between assessments.

Construct validity

Construct validity assesses whether questionnaire scores behave as expected based on predefined hypotheses. This may include examining relationships with other measures assessing similar or different constructs, or comparing scores between groups expected to differ in symptom severity or impact.

Criterion validity

Criterion validity may be evaluated where an appropriate reference or accepted gold-standard measure exists. For many patient-reported symptoms and experiences there is no true gold standard, in which case other approaches to assessing construct validity are generally more appropriate.

Responsiveness

Where a questionnaire is intended to measure change over time, responsiveness can be evaluated to determine whether scores are able to detect change in the construct being assessed.

Score interpretation

Further studies may help establish how scores should be interpreted, including severity categories and estimates of minimally important change or difference. These are specific to individual questionnaires and populations and should only be used where supported by appropriate evidence. Not every measurement property will be relevant to every ICIQ questionnaire. The extent and nature of validation should reflect the intended purpose of the questionnaire and the way in which its scores are to be used.

Further validation

Additional studies evaluating the measurement properties of existing ICIQ questionnaires are encouraged.

Researchers undertaking further validation should use the approved questionnaire as supplied and clearly describe the population, setting, methods and scoring approach used.

Researchers wishing to modify or further develop an existing ICIQ questionnaire should contact the ICIQ team before beginning this work.

Translation and cultural adaptation

New translations or cultural adaptations of ICIQ questionnaires require prior permission from the ICIQ team.

Where an approved translation already exists for the relevant language and cultural setting, this should normally be used rather than producing a new translation.

Translation and cultural adaptation should aim to preserve the meaning and concepts of the original questionnaire rather than simply produce a literal word-for-word translation. Regional adaptations may be appropriate where meaningful linguistic or cultural differences exist within the same language.

ICIQ has an established translation and linguistic validation process which includes forward translation, reconciliation, back translation, ICIQ review and cognitive testing with the target population.

Further psychometric evaluation of a translated version may also be appropriate depending on its intended use, particularly where comparisons are being made between language or cultural groups or data are to be pooled across countries.

Final approved translations are held within the ICIQ translation library and distributed through the ICIQ programme.

For full details of the translation process and requirements, please refer to the ICIQ Translation Guidelines.