Application of validity theory and methodology to patient-reported outcome measures (PROMs): building an argument for validity

Abstract

BackgroundData from subjective patient-reported outcome measures (PROMs) are now being used in the health sector to make or support decisions about individuals, groups and populations. Contemporary validity theorists define validity not as a statistical property of the test but as the extent to which empirical evidence supports the interpretation of test scores for an intended use. However, validity testing theory and methodology are rarely evident in the PROM validation literature. Application of this theory and methodology would provide structure for comprehensive validation planning to support improved PROM development and sound arguments for the validity of PROM score interpretation and use in each new context.ObjectiveThis paper proposes the application of contemporary validity theory and methodology to PROM validity testing.Illustrative exampleThe validity testing principles will be applied to a hypothetical case study with a focus on the interpretation and use of scores from a translated PROM that measures health literacy (the Health Literacy Questionnaire or HLQ).DiscussionAlthough robust psychometric properties of a PROM are a pre-condition to its use, a PROM’s validity lies in the sound argument that a network of empirical evidence supports the intended interpretation and use of PROM scores for decision making in a particular context. The health sector is yet to apply contemporary theory and methodology to PROM development and validation. The theoretical and methodological processes in this paper are offered as an advancement of the theory and practice of PROM validity testing in the health sector.

Health literacy and the health status of men with prostate cancer

“…Previous literature supports the validity and reliability of the HLQ as a sound multidimensional measure of health literacy in a variety of contexts . Based on current findings, the psychometric properties of the measure remain stable and can confidently be extended to prostate cancer samples and potentially to other cancer, chronic disease, and older all‐male samples.…”

“…The HLQ has been applied and tested in a variety of health contexts and populations . As the instrument developers suggest, the appropriateness of a tool for any particular setting can vary, and it is important to validate the data the HLQ generates in each specific context before interpreting findings based upon it . To date, the HLQ has not been tested in a sample of men with prostate cancer.…”

Health literacy: a new piece of the puzzle in psoriasis care? A cross‐sectional study

“…The questionnaire has no total score, as that could potentially mask individual needs in specific HL domains . The HLQ appears robust for its intended purpose of assessing HL in a range of settings and has shown excellent reliability …”

Measuring quality of life in life-threatening illness – content validity and response processes of MQOL-E and QOLLTI-F in Swedish patients and family carers

“…Investigation of response processes and understanding how people interpret and respond to items is particularly important for determining whether the items and scores can be interpreted in the same way when measurement instruments are translated and adapted for use in different cultures. Evidence pertaining to content validity and response processes is essential to ensuring linguistic equivalence and cultural appropriateness of the items and validity of the overall measurement instrument [20]. Therefore, the aim of this study was to translate and examine content validity and response processes during completion of MQOL-E and QOLLTI-F v2 among Swedish patients with life-threatening illness and family carers.…”