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'I suppose that depends on how I was feeling at the time': perspectives on questionnaires measuring quality of life and musculoskeletal pain

Objectives: This study aimed to investigate the thoughts and reasoning of respondents in relation to their experience of back and knee pain while they were completing validated health status questionnaires as part of two epidemiological surveys. Methods: Qualitative interviews with 10 participants who were sampled from previous questionnaire responders. Content analysis identified emerging themes. Analysis allowed for a comparison with other research, for a focus on disease-specific questionnaire interpretations, and use of additional survey material (i.e. annotations alongside questionnaire items and accompanying letters). Results: Adaptation to limitations and comparisons with previous self and/or others changed the way people responded to the standardized questions. The determination of specific periods of pain proved very difficult for respondents because pain, and low back pain in particular, was rarely experienced as a stable phenomenon. In addition, the time frames used in questionnaires were often at variance with the lived reality of pain and its effects on individuals' perceptions of time. Respondents tended to emphasize the context within which they experienced pain, and in the case of knee pain, often ranked this pain in relation to other health issues. Conclusions: In epidemiological studies, differences in interpretations are averaged across large samples, but we argue that a deeper understanding of the range of individual interpretations is important if one is to acknowledge the different meanings of pain within populations. The accounts of pain sufferers are highly complex and variable. Multi-method studies offer an opportunity to explore these using complementary approaches. This may lead to both more patient-centred research and health service provision.