The role of response domain and scale label in the quantitative interpretation of patient-reported outcome measure response options.

Purpose: Uncertainties exist in how respondents interpret response options in patient-reported outcome measures (PROMs), particularly across different domains and for different scale labels. The current study assessed how respondents quantitatively interpret common response options.

Methods: Members of the general public were recruited to this study via an online panel, stratified by age, gender, and having English as a first language. Participants completed background questions and were randomised to answer questions on one of three domains (i.e. loneliness (negatively phrased), happiness or activities (positively phrased)). Participants were asked to provide quantitative interpretations of response options (e.g. how many times per week is equal to "often") and to order several common response options (e.g. occasionally, sometimes) on a 0-100 slider scale. Chi-squared tests and regression analyses were used to assess whether response options were interpreted consistently across domains and respondent characteristics.

Results: Data from 1377 participants were analysed. There was general consistency in quantifying the number of times over the last 7 days to which each response option referred. Response options were consistently assigned a lower value in the loneliness than happiness and activities domains. Individual differences, such as age and English as a second language, explained some significant variation in responses, but less than domain.

Conclusion: Members of the public quantify common response options in a similar way, but their quantification is not equivalent across domains or every type of respondent. Recommendations for the use of certain scale labels over others in PROM development are provided.