Patient understanding of two commonly used patient reported outcome measures for primary care: a cognitive interview study.

The study provides information for both users of PEI/MYMOP and developers of individualised and transitional questionnaires. Users should heed the recommendation that MYMOP should be interview-administered, and this is likely to apply to other individualised scales. The PEI is open to hypothesis-guessing and may lack face-validity for a longer episode of care (e.g. in patients with chronic conditions). Developers should be cognisant that transitional scales can be inconsistently completed: some patients forget during completion that they are measuring change from baseline. Although generic questionnaires require the content to be more general than do disease-specific questionnaires, developers should avoid questions which allow broad and varied interpretations.